@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=Space+Grotesk:wght@500;700&display=swap');

:root {
  /* Colors from design.md - Light theme (default) */
  --primary: #15222D;
  --secondary: #6B7884;
  --tertiary: #00B0C7;
  --neutral: #FFFFFF;
  --surface: #F8FCFE;
  --on-primary: #FFFFFF;

  /* System mappings - Light theme */
  --bg-color: var(--neutral);
  --accent-color: var(--tertiary);
  --accent-hover: #008fa3;
  --block-bg: var(--surface);
  --text-main: var(--primary);
  --text-muted: var(--secondary);
  --border-color: #D1D9E0;
  --input-bg: #FFFFFF;

  /* Typography */
  --font-family-body: 'Inter', -apple-system, sans-serif;
  --font-family-display: 'Space Grotesk', -apple-system, sans-serif;
  --font-family: var(--font-family-body);
}

/* Dark theme */
[data-theme="dark"] {
  --primary: #E8EEF4;
  --secondary: #9AA5B1;
  --tertiary: #06C4DC;
  --neutral: #0F171E;
  --surface: #15202A;
  --on-primary: #0F171E;

  --bg-color: #0F171E;
  --accent-color: var(--tertiary);
  --accent-hover: #08D4ED;
  --block-bg: #1A2835;
  --text-main: var(--primary);
  --text-muted: var(--secondary);
  --border-color: #2A3845;
  --input-bg: #1A2835;
}

/* Smooth theme transition */
body,
.app-header,
.app-footer,
.panel,
.card,
.course-card,
.module-card,
.auth-container,
.form-control,
.discussion-textarea,
.data-table,
.quiz-question-card,
.certificate-card {
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}

/* Theme toggle button */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--border-color);
  background: transparent;
  cursor: pointer;
  transition: all 0.2s ease;
  padding: 0;
  flex-shrink: 0;
  margin-right: -32px;
}

.theme-toggle:hover {
  background-color: var(--block-bg);
  border-color: var(--accent-color);
}

.theme-toggle .feather,
.theme-toggle svg.feather {
  width: 20px;
  height: 20px;
  stroke: var(--text-main);
  fill: none;
  stroke-width: 2;
}

.theme-toggle .sun-icon {
  display: none;
}

.theme-toggle .moon-icon {
  display: block;
}

[data-theme="dark"] .theme-toggle .sun-icon {
  display: block;
}

[data-theme="dark"] .theme-toggle .moon-icon {
  display: none;
}

h1,
h2,
h3,
h4,
h5,
h6,
.logo-text,
.course-title,
.hero-content h1,
.auth-header h1,
.page-header h1,
.completion-banner h1,
.certificate-logo,
.certificate-heading {
  font-family: var(--font-family-display);
  letter-spacing: -0.03em;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  font-size: 16px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  text-decoration: none;
  color: var(--accent-color);
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-hover);
}

/* ==================================
   HEADER
=================================== */
.app-header {
  background-color: var(--bg-color);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  height: 70px;
  display: flex;
  align-items: center;
  gap: 40px;
}

.logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
  margin-top: -2px;
}

.logo-text {
  font-size: 26px;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.5px;
  line-height: 1;
}

.logo-accent {
  color: var(--accent-color);
}

.main-nav {
  display: flex;
  gap: 30px;
  margin-right: auto;
}

.main-nav a {
  color: var(--text-main);
  font-weight: 500;
  font-size: 15px;
  line-height: 26px;
}

.main-nav a:hover {
  color: var(--accent-color);
}

.user-actions {
  display: flex;
  align-items: center;
  gap: 15px;
}

.user-name {
  font-size: 14px;
  font-weight: 500;
}

.nav-link {
  color: var(--text-main);
  font-weight: 500;
}

/* ==================================
   BUTTONS
=================================== */
.btn {
  display: inline-block;
  padding: 12px 20px;
  border-radius: var(--rounded-md, 4px);
  font-family: var(--font-family-display);
  font-weight: 500;
  letter-spacing: 0.02em;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 1px solid transparent;
  text-align: center;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background-color: var(--accent-color);
  color: #FFFFFF !important;
}

.btn-primary:hover {
  background-color: var(--accent-hover);
}

.btn-outline {
  background-color: transparent;
  color: var(--accent-color) !important;
  border-color: var(--accent-color);
}

.btn-outline:hover {
  background-color: var(--block-bg);
}

.btn-large {
  padding: 14px 28px;
  font-size: 16px;
}

/* ==================================
   MAIN CONTENT
=================================== */
.app-main {
  flex: 1;
}

/* ==================================
   HERO SECTION
=================================== */
.hero-section {
  position: relative;
  padding: 140px 20px 80px;
  text-align: center;
  background-color: var(--block-bg);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  border-bottom: 1px solid var(--border-color);
  overflow: hidden;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background: rgba(21, 34, 45, 0.85);
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 800px;
  margin: 0 auto;
}

.hero-content h1 {
  font-size: 42px;
  font-weight: 800;
  color: #FFFFFF;
  margin-bottom: 20px;
  line-height: 1.2;
  letter-spacing: -1px;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.hero-content p {
  font-size: 18px;
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: 40px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  gap: 20px;
  justify-content: center;
}

.hero-actions .btn-outline {
  color: #FFFFFF !important;
  border-color: #FFFFFF;
}

.hero-actions .btn-outline:hover {
  background-color: rgba(255, 255, 255, 0.15);
}

.hero-rotating-container {
  display: inline-block;
  position: relative;
  text-align: center;
}

.rotating-placeholder {
  visibility: hidden;
  display: block;
}

.rotating-text {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  display: inline-block;
  color: var(--accent-color);
  transition: opacity 0.5s ease, transform 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.15);
  opacity: 1;
  transform: translateX(0);
}

.rotating-text.hide {
  opacity: 0;
  transform: translateX(30px);
}

.rotating-text.prepare {
  transition: none;
  opacity: 0;
  transform: translateX(-30px);
}

@media (min-width: 768px) {
  .mobile-break {
    display: none;
  }
}

/* ==================================
   COURSES SECTION
=================================== */
.courses-section {
  padding: 30px 20px 60px;
  max-width: 1200px;
  margin: 0 auto;
}

.section-container h2 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 30px;
  color: var(--text-main);
  text-align: center;
}

.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.course-card {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  cursor: pointer;
  display: flex;
  flex-direction: column;
}

.course-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 32px rgba(21, 34, 45, 0.12);
}

.course-image {
  height: 140px;
  width: 100%;
  background-size: cover;
  background-position: center;
}

.bg-blue {
  background-color: #e3f2fd;
}

.bg-teal {
  background-color: #e0f2f1;
}

.bg-gray {
  background-color: #eceff1;
}

.bg-dark {
  background-color: #37474f;
}

.course-info {
  padding: 20px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.course-university {
  font-size: 12px;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 600;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
}

.course-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
  line-height: 1.3;
}

.course-instructor {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 20px;
  flex: 1;
}

.course-meta {
  display: flex;
  align-items: center;
  font-size: 13px;
  border-top: 1px solid var(--border-color);
  padding-top: 15px;
}

.difficulty {
  font-weight: 600;
}

.difficulty.begin {
  color: #2e7d32;
}

.difficulty.mid {
  color: #f57c00;
}

.difficulty.hard {
  color: #d32f2f;
}

/* ==================================
   FOOTER
=================================== */
.app-footer {
  background-color: var(--block-bg);
  border-top: 1px solid var(--border-color);
  padding: 24px 20px;
  margin-top: 60px;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  text-align: center;
}

.logo-text-footer {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-main);
  display: block;
  margin-bottom: 4px;
}

.footer-container p {
  color: var(--text-muted);
  font-size: 14px;
  margin: 0;
}

.footer-link {
  display: inline-block;
  margin-top: 8px;
  color: var(--accent-color);
  font-size: 13px;
  text-decoration: none;
}

.footer-link:hover {
  text-decoration: underline;
}

.footer-col h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 20px;
}

.footer-col a {
  display: block;
  color: var(--text-muted);
  margin-bottom: 10px;
  font-size: 14px;
}

.footer-col a:hover {
  color: var(--accent-color);
}

/* ==================================
   AUTH FORMS & CONTAINERS
=================================== */
.auth-container {
  max-width: 440px;
  margin: 60px auto;
  padding: 40px;
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
}

.auth-header {
  text-align: center;
  margin-bottom: 30px;
}

.auth-header h1 {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
  letter-spacing: -0.5px;
}

.auth-header p {
  color: var(--text-muted);
  font-size: 15px;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 8px;
}

.form-control {
  width: 100%;
  padding: 12px 16px;
  font-size: 15px;
  font-family: inherit;
  color: var(--text-main);
  background-color: var(--input-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  transition: all 0.2s ease;
}

.form-control:focus {
  outline: none;
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px rgba(0, 177, 201, 0.15);
}

.btn-block {
  width: 100%;
  display: block;
  margin-top: 24px;
}

.auth-footer {
  margin-top: 24px;
  text-align: center;
  font-size: 14px;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  padding-top: 20px;
}

.auth-footer a {
  font-weight: 600;
}

.alert-error {
  background-color: #fef2f2;
  border: 1px solid #fecaca;
  color: #b91c1c;
  padding: 12px 16px;
  border-radius: 6px;
  margin-bottom: 20px;
  font-size: 14px;
}

.alert-success {
  background-color: #f0fdf4;
  border: 1px solid #bbf7d0;
  color: #15803d;
  padding: 12px 16px;
  border-radius: 6px;
  margin-bottom: 20px;
  font-size: 14px;
}

.alert-error ul {
  margin-left: 20px;
  margin-top: 5px;
}

/* Inline field-level validation */
.field-error {
  color: #dc2626;
  font-size: 13px;
  margin-top: 6px;
}

[data-theme="dark"] .field-error {
  color: #fca5a5;
}

.form-control.field-invalid,
.field-invalid {
  border-color: #dc2626 !important;
}

.form-control.field-invalid:focus {
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.15);
}

/* ==================================
   CONTENT CONTAINERS
=================================== */
.content-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 20px;
}

.content-container-narrow {
  max-width: 700px;
  margin: 40px auto;
  padding: 0 20px;
}

/* ==================================
   PAGE HEADERS
=================================== */
.page-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border-color);
}

.page-header h1 {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-main);
  margin: 0;
}

/* ==================================
   BREADCRUMB / BACK LINK
=================================== */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: 24px;
  transition: color 0.2s ease;
}

.back-link:hover {
  color: var(--accent-color);
}

/* ==================================
   PANELS / CARDS
=================================== */
.panel {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 24px;
  margin-bottom: 24px;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.panel-header h2,
.panel-header h3 {
  margin: 0;
  font-weight: 600;
}

/* ==================================
   DATA TABLES
=================================== */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.data-table thead tr {
  border-bottom: 2px solid var(--border-color);
}

.data-table th {
  padding: 12px 16px;
  text-align: left;
  font-weight: 600;
  color: var(--text-muted);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  white-space: nowrap;
}

.data-table td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-main);
  vertical-align: middle;
}

.data-table tbody tr:hover {
  background-color: var(--block-bg);
}

.data-table tbody tr:last-child td {
  border-bottom: none;
}

/* Responsive table wrapper — horizontal scroll on mobile */
.table-responsive {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.table-responsive .data-table th,
.table-responsive .data-table td {
  white-space: nowrap;
}

/* Column hiding */
.col-hide-mobile {
  display: table-cell;
}

/* Action buttons row in table cells */
.table-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.table-actions .btn-link-danger {
  margin: 0;
}

/* ==================================
   BADGES
=================================== */
.badge {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 12px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.3px;
}

.badge-draft {
  background-color: #fef3c7;
  color: #92400e;
}

.badge-published {
  background-color: #d1fae5;
  color: #065f46;
}

.badge-archived {
  background-color: #e5e7eb;
  color: #4b5563;
}

/* ==================================
   BUTTON VARIANTS
=================================== */
.btn-success {
  background-color: #059669;
  color: #fff !important;
}

.btn-success:hover {
  background-color: #047857;
}

.btn-danger {
  background-color: #dc2626;
  color: #fff !important;
  border-color: #dc2626;
}

.btn-danger:hover {
  background-color: #b91c1c;
}

.btn-secondary {
  background-color: var(--block-bg);
  color: var(--text-main) !important;
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--border-color);
}

.btn-sm {
  padding: 6px 12px;
  font-size: 13px;
}

.btn-xs {
  padding: 3px 8px;
  font-size: 12px;
  border-radius: 3px;
}

.btn-icon {
  background: none;
  border: 1px solid var(--border-color);
  cursor: pointer;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 14px;
  transition: all 0.2s ease;
  line-height: 1;
}

.btn-icon:hover {
  background-color: var(--block-bg);
  border-color: var(--accent-color);
}

.btn-link-danger {
  background: none;
  border: none;
  color: #dc2626;
  cursor: pointer;
  padding: 0;
  font-size: 13px;
  font-weight: 500;
  transition: color 0.2s ease;
}

.btn-link-danger:hover {
  color: #991b1b;
}

.btn-icon-feather {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 2px 6px;
  line-height: 1;
}

.btn-icon-feather .feather {
  width: 14px;
  height: 14px;
  stroke: var(--text-main);
  fill: none;
}

[data-theme="dark"] .btn-icon-feather .feather {
  stroke: var(--text-main);
}

.inline-form {
  display: inline;
}

/* Forms inside flex containers — align buttons with siblings */
:where(.page-header, .panel-header, .module-actions, .hero-actions) > .inline-form,
div[style*="display: flex"] > .inline-form {
  display: flex;
  align-items: center;
}

/* ==================================
   FORM EXTENSIONS
=================================== */
.form-control-select {
  width: 100%;
  padding: 12px 16px;
  font-size: 15px;
  font-family: inherit;
  color: var(--text-main);
  background-color: var(--input-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  transition: all 0.2s ease;
  appearance: auto;
}

.form-control-select:focus {
  outline: none;
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px rgba(0, 177, 201, 0.15);
}

textarea.form-control {
  resize: vertical;
  min-height: 80px;
}

input[type="file"] {
  color: var(--text-main);
  background-color: var(--input-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 8px 12px;
  font-size: 14px;
  font-family: inherit;
}

input[type="file"]::file-selector-button {
  padding: 6px 14px;
  border: none;
  border-radius: 4px;
  background-color: var(--accent-color);
  color: var(--on-primary);
  font-size: 13px;
  font-family: inherit;
  cursor: pointer;
  margin-right: 10px;
}

input[type="file"]::file-selector-button:hover {
  background-color: var(--accent-hover);
}

.form-hint {
  display: block;
  color: var(--text-muted);
  font-size: 13px;
  margin-top: 6px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.cover-picker {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 10px;
}

.cover-picker-option {
  cursor: pointer;
  display: block;
}

.cover-picker-option input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.cover-picker-option img,
.cover-picker-auto {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  border-radius: 8px;
  border: 2px solid var(--border-color);
  box-sizing: border-box;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.cover-picker-auto {
  background: var(--block-bg);
  color: var(--text-muted);
  font-size: 13px;
  text-align: center;
}

.cover-picker-option input:checked + img,
.cover-picker-option input:checked + .cover-picker-auto {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 2px var(--accent-color);
}

.form-actions {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 30px;
  padding-top: 20px;
  border-top: 1px solid var(--border-color);
}

/* ==================================
   DIVIDERS
=================================== */
.divider {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 30px 0;
}

/* ==================================
   DETAIL INFO TABLE
=================================== */
.detail-table {
  margin-bottom: 24px;
}

.detail-table tr td {
  padding: 8px 0;
  font-size: 15px;
}

.detail-table tr td:first-child {
  font-weight: 600;
  color: var(--text-muted);
  padding-right: 24px;
  white-space: nowrap;
}

/* ==================================
   MODULE / LESSON CARDS
=================================== */
.module-card {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  margin-bottom: 20px;
  overflow: hidden;
}

.module-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 20px;
  background: var(--block-bg);
  border-bottom: 1px solid var(--border-color);
}

.module-card-header h3 {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}

.module-card-header .sort-order {
  color: var(--text-muted);
  font-weight: 400;
}

.module-card-body {
  padding: 16px 20px;
}

.module-description {
  color: var(--text-muted);
  font-size: 14px;
  margin-bottom: 12px;
}

.module-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.module-actions .inline-form {
  display: flex;
  align-items: center;
}

.sort-controls {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-right: 8px;
  align-items: center;
}

.lesson-sort-cell {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.lesson-sort-cell > span {
  font-weight: 500;
  font-size: 14px;
}

.lesson-sort-cell form {
  margin: 0;
}

.no-items {
  color: var(--text-muted);
  font-size: 14px;
  font-style: italic;
}

/* ==================================
   QUIZ SPECIFIC
=================================== */
.quiz-question-card {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 20px;
  margin-bottom: 16px;
}

.quiz-question-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 12px;
}

.quiz-question-meta {
  color: var(--text-muted);
  font-size: 13px;
  margin-left: 8px;
}

.quiz-option-list {
  margin: 0;
  padding-left: 20px;
}

.quiz-option-list li {
  padding: 4px 0;
  font-size: 14px;
}

.quiz-option-correct {
  color: #059669;
  font-weight: 600;
}

.quiz-result-banner {
  border: 2px solid;
  border-radius: 8px;
  padding: 24px;
  margin-bottom: 30px;
  text-align: center;
}

.quiz-result-banner.passed {
  border-color: #059669;
  background-color: #ecfdf5;
}

.quiz-result-banner.failed {
  border-color: #dc2626;
  background-color: #fef2f2;
}

.quiz-result-banner h2 {
  margin: 0 0 8px;
}

.quiz-result-banner.passed h2 {
  color: #059669;
}

.quiz-result-banner.failed h2 {
  color: #dc2626;
}

.quiz-answer-card {
  border: 1px solid var(--border-color);
  border-left: 4px solid;
  border-radius: 4px;
  padding: 16px;
  margin-bottom: 16px;
}

.quiz-answer-card.correct {
  border-left-color: #059669;
}

.quiz-answer-card.incorrect {
  border-left-color: #dc2626;
}

.quiz-answer-card.pending {
  border-left-color: #f59e0b;
}

/* ==================================
   FILE UPLOAD
=================================== */
.file-input-wrapper {
  position: relative;
}

.file-input-wrapper input[type="file"] {
  font-family: inherit;
  font-size: 14px;
}

.file-dropzone {
  position: relative;
  border: 2px dashed var(--border-color);
  border-radius: 10px;
  padding: 28px 16px;
  text-align: center;
  background: var(--block-bg);
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.file-dropzone.is-dragover {
  border-color: var(--accent-color);
  background: color-mix(in srgb, var(--accent-color) 8%, var(--block-bg));
}

.file-dropzone-input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
  margin: 0;
}

.file-dropzone-icon {
  font-size: 22px;
  line-height: 1;
  display: block;
  margin-bottom: 8px;
}

.file-dropzone-hint p {
  margin: 0;
  font-size: 14px;
  color: var(--text-main);
}

.file-dropzone-hint .form-hint {
  margin-top: 8px;
}

.file-dropzone-link {
  color: var(--accent-color);
  text-decoration: underline;
}

.file-dropzone-list {
  list-style: none;
  padding: 0;
  margin: 12px 0 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.file-dropzone-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 12px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: var(--input-bg);
  font-size: 13px;
}

.file-dropzone-item-name {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.file-dropzone-item-size {
  color: var(--text-muted);
  white-space: nowrap;
  margin-left: auto;
  padding-left: 8px;
}

.file-dropzone-item-remove {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 16px;
  line-height: 1;
  padding: 0 2px;
}

.file-dropzone-item-remove:hover {
  color: #dc2626;
}

.file-dropzone-error {
  margin-top: 8px;
  font-size: 13px;
  color: #dc2626;
}

/* ==================================
   SIDEBAR LESSON LINK
=================================== */
.sidebar-lesson-link {
  border-left: 3px solid transparent;
  color: var(--text-main);
}

.sidebar-lesson-link.active {
  border-left-color: var(--accent-color);
  background: var(--block-bg);
  color: var(--accent-color);
  font-weight: 600;
}

/* ==================================
   SIDEBAR ATTACHMENTS
=================================== */
.sidebar-attachment-list {
  list-style: none;
  padding: 0;
  margin: 2px 0 6px 30px;
}

.sidebar-attachment-link {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px 4px 7px;
  border-left: 3px solid transparent;
  border-radius: 6px;
  font-size: 13px;
  color: var(--text-muted);
  text-decoration: none;
}

.sidebar-attachment-link:hover {
  color: var(--accent-color);
  background: var(--block-bg);
}

.sidebar-attachment-link.active {
  border-left-color: var(--accent-color);
  background: var(--block-bg);
  color: var(--accent-color);
  font-weight: 600;
}

/* ==================================
   ATTACHMENT INLINE PREVIEW
=================================== */
.attachment-inline-preview {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  margin-bottom: 24px;
  overflow: hidden;
  background: var(--bg-color);
}

.attachment-inline-preview-frame {
  width: 100%;
  height: 90vh;
  min-height: 700px;
  border: none;
  background: #fff;
}

/* `display: block` only applies while the iframe isn't [hidden] — an
   unconditional `display` here would outrank the browser's own
   `[hidden] { display: none }` rule (same specificity, but author beats
   user-agent), keeping it visible no matter what JS sets .hidden to. */
.attachment-inline-preview-frame:not([hidden]) {
  display: block;
}

/* ==================================
   VIDEO PLAYER
   Native controls look completely different per browser, so the video
   preview gets its own custom chrome instead — dark stage (video-player
   convention) with controls themed via the site's accent color.
=================================== */
.video-player {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  max-height: 90vh;
  background: #000;
}

.video-player-el {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
  cursor: pointer;
  background: #000;
}

.video-player:fullscreen {
  aspect-ratio: auto;
  max-height: none;
}

.video-player-overlay-btn {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 64px;
  height: 64px;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.55);
  border: 2px solid rgba(255, 255, 255, 0.85);
  color: #fff;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

/* Same reasoning as .attachment-inline-preview-frame above: `display` must
   stay conditional or it outranks `[hidden] { display: none }` and the
   overlay button never actually disappears while the video is playing. */
.video-player-overlay-btn:not([hidden]) {
  display: flex;
}

.video-player-overlay-btn:hover {
  background: var(--accent-color);
  border-color: var(--accent-color);
}

.video-player-overlay-btn svg {
  margin-left: 3px;
}

.video-player-controls {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  background: linear-gradient(to top, rgba(0, 0, 0, 0.75), rgba(0, 0, 0, 0));
}

.video-ctrl-btn {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  padding: 2px;
  background: none;
  border: none;
  color: #fff;
  cursor: pointer;
}

.video-ctrl-btn:hover {
  color: var(--accent-color);
}

.video-time {
  flex-shrink: 0;
  min-width: 34px;
  text-align: center;
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  color: #fff;
}

.video-seek {
  flex: 1;
  min-width: 0;
  accent-color: var(--accent-color);
  cursor: pointer;
}

.video-volume {
  width: 70px;
  flex-shrink: 0;
  accent-color: var(--accent-color);
  cursor: pointer;
}

/* ==================================
   CHECKBOX / RADIO styled
=================================== */
.quiz-take-option {
  display: block;
  padding: 10px 14px;
  margin-bottom: 6px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 15px;
}

.quiz-take-option:hover {
  background-color: var(--block-bg);
  border-color: var(--accent-color);
}

.quiz-take-option input {
  margin-right: 10px;
}

/* ==================================
   404 PAGE
=================================== */
.not-found-container {
  text-align: center;
  padding: 100px 20px;
}

.not-found-container h1 {
  font-size: 120px;
  font-weight: 800;
  color: var(--accent-color);
  margin-bottom: 10px;
  line-height: 1;
  letter-spacing: -4px;
}

.not-found-container p {
  color: var(--text-muted);
  font-size: 16px;
  margin-bottom: 12px;
}

.not-found-container .btn {
  margin-top: 20px;
}

/* Responsive */
@media (max-width: 768px) {
  .hero-content h1 {
    font-size: 32px;
  }

  .main-nav {
    display: none;
  }

  .footer-container {
    grid-template-columns: 1fr;
  }

  .completion-banner h1 {
    font-size: 28px;
  }

  .certificate-card-inner {
    padding: 24px;
  }

  .theme-toggle {
    width: 36px;
    height: 36px;
  }
}

/* ==================================
   COURSE COMPLETION PAGE
=================================== */
.completion-banner {
  text-align: center;
  padding: 48px 24px 36px;
  margin-bottom: 32px;
}

.completion-icon {
  font-size: 64px;
  margin-bottom: 12px;
  animation: completionBounce 0.6s ease-out;
}

@keyframes completionBounce {
  0% {
    transform: scale(0.3) translateY(30px);
    opacity: 0;
  }

  60% {
    transform: scale(1.1) translateY(-8px);
    opacity: 1;
  }

  100% {
    transform: scale(1) translateY(0);
  }
}

.completion-banner h1 {
  font-size: 36px;
  font-weight: 800;
  color: #05A4BA;
  margin-bottom: 8px;
  letter-spacing: -0.5px;
}

.completion-subtitle {
  font-size: 18px;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.completion-course-title {
  font-size: 22px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 16px;
}

.completion-date {
  font-size: 15px;
  color: var(--text-muted);
}

/* ==================================
   CERTIFICATE CARD
=================================== */
.certificate-card {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
  background: var(--surface);
  box-shadow: 0 16px 48px rgba(21, 34, 45, 0.08);
}

.certificate-card-inner {
  padding: 40px 32px;
  text-align: center;
  position: relative;
}

.certificate-ornament-top,
.certificate-ornament-bottom {
  height: 6px;
  background: var(--tertiary);
}

.certificate-body {
  padding: 20px 0;
}

.certificate-logo {
  font-size: 20px;
  font-weight: 700;
  color: #05A4BA;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.certificate-heading {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 24px;
}

.certificate-text {
  font-size: 15px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.certificate-name {
  font-size: 26px;
  font-weight: 700;
  color: var(--text-main);
  margin: 8px 0 16px;
  font-style: italic;
}

.certificate-course {
  font-size: 20px;
  font-weight: 600;
  color: #05A4BA;
  margin: 8px 0 28px;
}

.certificate-details {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 20px;
  padding-top: 20px;
  border-top: 1px solid #b2ebf2;
}

.certificate-detail {
  text-align: center;
}

.certificate-detail-label {
  display: block;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.certificate-detail-value {
  display: block;
  font-size: 15px;
  font-weight: 600;
  color: var(--text-main);
}

/* ==================================
   LOCKED LESSON ALERT
=================================== */
.alert-locked {
  background: #fffbeb;
  border: 1px solid #fcd34d;
  border-left: 4px solid #f59e0b;
  border-radius: 8px;
  padding: 20px 24px;
  margin-bottom: 24px;
}

.alert-locked strong {
  font-size: 16px;
  color: #92400e;
  display: block;
  margin-bottom: 6px;
}

.alert-locked p {
  font-size: 14px;
  color: #78350f;
  margin: 0;
}

/* ==================================
   INLINE COURSE COMPLETION BANNER
=================================== */
.completion-inline-banner {
  display: flex;
  align-items: center;
  gap: 16px;
  background: linear-gradient(135deg, #ecfdf5, #d1fae5);
  border: 2px solid #059669;
  border-radius: 10px;
  padding: 16px 20px;
  margin-bottom: 24px;
}

.completion-inline-icon {
  font-size: 32px;
  flex-shrink: 0;
}

.completion-inline-banner strong {
  color: #065f46;
  font-size: 16px;
}

.completion-inline-banner p {
  color: #047857;
}

.completion-inline-banner .btn {
  flex-shrink: 0;
  margin-left: auto;
}

/* ==================================
   UNENROLL / DANGER OUTLINE BUTTON
=================================== */
.btn-danger-outline {
  background: transparent;
  color: #dc2626 !important;
  border-color: #fecaca;
}

.btn-danger-outline:hover {
  background: #fef2f2;
  border-color: #dc2626;
}

/* ==================================
   QUIZ RESULT BANNER — pending state
=================================== */
.quiz-result-banner.pending {
  border-color: #f59e0b;
  background-color: #fffbeb;
}

.quiz-result-banner.pending h2 {
  color: #92400e;
}

/* ==================================
   DARK THEME OVERRIDES
=================================== */
[data-theme="dark"] .alert-error {
  background-color: rgba(220, 38, 38, 0.15);
  border-color: rgba(220, 38, 38, 0.3);
  color: #fca5a5;
}

[data-theme="dark"] .alert-success {
  background-color: rgba(5, 150, 105, 0.15);
  border-color: rgba(5, 150, 105, 0.3);
  color: #6ee7b7;
}

[data-theme="dark"] .quiz-result-banner.passed {
  border-color: #059669;
  background-color: rgba(5, 150, 105, 0.15);
}

[data-theme="dark"] .quiz-result-banner.passed h2 {
  color: #6ee7b7;
}

[data-theme="dark"] .quiz-result-banner.failed {
  border-color: #dc2626;
  background-color: rgba(220, 38, 38, 0.15);
}

[data-theme="dark"] .quiz-result-banner.failed h2 {
  color: #fca5a5;
}

[data-theme="dark"] .quiz-result-banner.pending {
  border-color: #f59e0b;
  background-color: rgba(245, 158, 11, 0.15);
}

[data-theme="dark"] .quiz-result-banner.pending h2 {
  color: #fcd34d;
}

[data-theme="dark"] .badge-draft {
  background-color: rgba(254, 243, 199, 0.2);
  color: #fde68a;
}

[data-theme="dark"] .badge-published {
  background-color: rgba(16, 185, 129, 0.2);
  color: #6ee7b7;
}

[data-theme="dark"] .badge-archived {
  background-color: rgba(156, 163, 175, 0.2);
  color: #d1d5db;
}

[data-theme="dark"] .bg-blue {
  background-color: rgba(59, 130, 246, 0.2);
}

[data-theme="dark"] .bg-teal {
  background-color: rgba(20, 184, 166, 0.2);
}

[data-theme="dark"] .bg-gray {
  background-color: rgba(107, 114, 128, 0.2);
}

[data-theme="dark"] .bg-dark {
  background-color: #2A3845;
}

[data-theme="dark"] .difficulty.begin {
  color: #86efac;
}

[data-theme="dark"] .difficulty.mid {
  color: #fdba74;
}

[data-theme="dark"] .difficulty.hard {
  color: #fca5a5;
}

[data-theme="dark"] .completion-banner {
  background: linear-gradient(135deg, rgba(5, 150, 105, 0.15), rgba(16, 185, 129, 0.1));
}

[data-theme="dark"] .completion-inline-banner {
  background: linear-gradient(135deg, rgba(5, 150, 105, 0.15), rgba(16, 185, 129, 0.1));
  border-color: rgba(5, 150, 105, 0.5);
}

[data-theme="dark"] .completion-inline-banner strong {
  color: #6ee7b7;
}

[data-theme="dark"] .completion-inline-banner p {
  color: #34d399;
}

[data-theme="dark"] .alert-locked {
  background: rgba(245, 158, 11, 0.15);
  border-color: rgba(245, 158, 11, 0.3);
  border-left-color: #f59e0b;
}

[data-theme="dark"] .alert-locked strong {
  color: #fcd34d;
}

[data-theme="dark"] .alert-locked p {
  color: #fbbf24;
}

[data-theme="dark"] .btn-danger-outline {
  background: transparent;
  color: #fca5a5 !important;
  border-color: rgba(220, 38, 38, 0.3);
}

[data-theme="dark"] .btn-danger-outline:hover {
  background: rgba(220, 38, 38, 0.15);
  border-color: #dc2626;
}

[data-theme="dark"] .quiz-option-correct {
  color: #6ee7b7;
}

[data-theme="dark"] .quiz-answer-card.correct {
  border-left-color: #059669;
  background-color: rgba(5, 150, 105, 0.1);
}

[data-theme="dark"] .quiz-answer-card.incorrect {
  border-left-color: #dc2626;
  background-color: rgba(220, 38, 38, 0.1);
}

[data-theme="dark"] .quiz-answer-card.pending {
  border-left-color: #f59e0b;
  background-color: rgba(245, 158, 11, 0.1);
}

[data-theme="dark"] .quiz-take-option {
  background-color: rgba(255, 255, 255, 0.02);
}

[data-theme="dark"] .quiz-take-option:hover {
  background-color: rgba(255, 255, 255, 0.05);
}

[data-theme="dark"] .form-control-select {
  color: var(--text-main);
  border-color: var(--border-color);
  color-scheme: dark;
}

[data-theme="dark"] .form-control {
  color-scheme: dark;
}

[data-theme="dark"] .discussion-textarea {
  background-color: var(--input-bg);
  color: var(--text-main);
  border-color: var(--border-color);
  color-scheme: dark;
}

[data-theme="dark"] .data-table tbody tr:hover {
  background-color: rgba(255, 255, 255, 0.03);
}

[data-theme="dark"] .course-card:hover {
  box-shadow: 0 16px 32px rgba(0, 0, 0, 0.4);
}

[data-theme="dark"] .certificate-card {
  background: #1A2835;
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.4);
}

[data-theme="dark"] .certificate-details {
  border-top-color: rgba(6, 196, 220, 0.3);
}

[data-theme="dark"] .hero-overlay {
  background: rgba(15, 23, 30, 0.9);
}

/* ==================================
   HTMX INDICATORS & ANIMATIONS
=================================== */

/* Loading indicator - spinner */
.htmx-indicator {
  display: none;
  opacity: 0;
  transition: opacity 200ms ease-in;
}

.htmx-request .htmx-indicator,
.htmx-indicator.htmx-request {
  display: inline-block;
  opacity: 1;
}

/* Spinner animation */
@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.spinner {
  width: 18px;
  height: 18px;
  border: 2px solid var(--border-color);
  border-top-color: var(--accent-color);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
  display: inline-block;
  vertical-align: middle;
  margin-right: 8px;
}

/* Smooth swap for HTMX content */
.htmx-settling {
  opacity: 0;
  transition: opacity 200ms ease-in;
}

/* Fade out for removed elements */
.htmx-swapping {
  opacity: 0;
  transition: opacity 200ms ease-in;
}

/* Disabled state during request */
.htmx-request.btn {
  pointer-events: none;
  opacity: 0.6;
}

.htmx-request.btn::after {
  content: '';
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
  margin-left: 8px;
  vertical-align: middle;
}

/* Toast notifications */
.toast-container {
  position: fixed;
  top: 80px;
  right: 20px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toast {
  padding: 14px 20px;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 500;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
  animation: slideIn 0.3s ease-out;
  max-width: 400px;
}

.toast-success {
  background: #d1fae5;
  color: #065f46;
  border-left: 4px solid #059669;
}

.toast-error {
  background: #fef2f2;
  color: #b91c1c;
  border-left: 4px solid #dc2626;
}

.toast-info {
  background: #e0f2fe;
  color: #075985;
  border-left: 4px solid #0284c7;
}

[data-theme="dark"] .toast-success {
  background: rgba(5, 150, 105, 0.2);
  color: #6ee7b7;
  border-left-color: #059669;
}

[data-theme="dark"] .toast-error {
  background: rgba(220, 38, 38, 0.2);
  color: #fca5a5;
  border-left-color: #dc2626;
}

[data-theme="dark"] .toast-info {
  background: rgba(2, 132, 199, 0.2);
  color: #7dd3fc;
  border-left-color: #0284c7;
}

@keyframes slideIn {
  from {
    transform: translateX(100%);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

@keyframes slideOut {
  from {
    transform: translateX(0);
    opacity: 1;
  }
  to {
    transform: translateX(100%);
    opacity: 0;
  }
}

.toast.removing {
  animation: slideOut 0.3s ease-out forwards;
}

/* ==================================
   FLASH MESSAGES (server-rendered)
=================================== */
.flash-stack {
  max-width: 1200px;
  margin: 24px auto 0;
  padding: 0 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.flash {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  border: 1px solid transparent;
  border-left-width: 4px;
  animation: flashIn 0.3s ease-out;
}

.flash .feather,
.flash [data-feather] {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
}

.flash-text {
  flex: 1;
}

.flash-close {
  background: none;
  border: none;
  cursor: pointer;
  color: inherit;
  opacity: 0.6;
  padding: 0;
  display: inline-flex;
  transition: opacity 0.15s;
}

.flash-close:hover {
  opacity: 1;
}

.flash-success {
  background: #f0fdf4;
  border-color: #059669;
  color: #15803d;
}

.flash-error {
  background: #fef2f2;
  border-color: #dc2626;
  color: #b91c1c;
}

.flash-warning {
  background: #fffbeb;
  border-color: #d97706;
  color: #b45309;
}

.flash-info {
  background: #e0f2fe;
  border-color: #0284c7;
  color: #075985;
}

[data-theme="dark"] .flash-success {
  background: rgba(5, 150, 105, 0.15);
  color: #6ee7b7;
}

[data-theme="dark"] .flash-error {
  background: rgba(220, 38, 38, 0.15);
  color: #fca5a5;
}

[data-theme="dark"] .flash-warning {
  background: rgba(217, 119, 6, 0.15);
  color: #fcd34d;
}

[data-theme="dark"] .flash-info {
  background: rgba(2, 132, 199, 0.15);
  color: #7dd3fc;
}

.flash.removing {
  animation: flashOut 0.3s ease-out forwards;
}

/* ==================================
   CATALOG SEARCH + PAGINATION
=================================== */
.catalog-search {
  display: flex;
  gap: 10px;
  max-width: 640px;
  margin: 0 auto 16px;
  flex-wrap: wrap;
}

.catalog-search .form-control {
  flex: 1;
  min-width: 200px;
}

.catalog-search-summary {
  text-align: center;
  color: var(--text-muted);
  font-size: 14px;
  margin-bottom: 24px;
}

.pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 40px;
}

.pagination-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  height: 40px;
  padding: 0 12px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background: var(--block-bg);
  color: var(--text-main);
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

a.pagination-link:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.pagination-link.is-current {
  background: var(--accent-color);
  border-color: var(--accent-color);
  color: #fff;
  cursor: default;
}

.pagination-link.is-disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

[data-theme="dark"] .pagination-link {
  background: rgba(255, 255, 255, 0.04);
}

@keyframes flashIn {
  from { transform: translateY(-8px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

@keyframes flashOut {
  from { transform: translateY(0); opacity: 1; height: auto; }
  to { transform: translateY(-8px); opacity: 0; height: 0; padding: 0; margin: 0; }
}

/* ==================================
   RESPONSIVE IMPROVEMENTS
=================================== */

/* Mobile menu button (hidden on desktop) */
.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  color: var(--text-main);
  order: -1;
}

.mobile-menu-btn .feather,
.mobile-menu-btn svg.feather {
  width: 24px;
  height: 24px;
  stroke: var(--text-main);
  fill: none;
  stroke-width: 2;
  display: block;
}

/* Elements visible only on mobile — hidden on desktop */
.nav-divider {
  display: none;
  border: 0;
  border-top: 1px solid var(--border-color);
  margin: 4px 0;
}

.nav-user-info {
  display: none;
  font-size: 13px;
  color: var(--text-muted);
  padding: 4px 0;
}

.nav-logout-form {
  display: none;
}

.nav-login-link {
  display: none;
}

.btn-block-mobile {
  width: 100%;
}

/* ==================================
   MOBILE — ≤768px
   =================================== */
@media (max-width: 768px) {
  .app-header {
    position: sticky;
    top: 0;
    z-index: 1000;
  }

  /* Top bar: [☰] [KUcourse] [🌙] — single row */
  .header-container {
    display: flex;
    align-items: center;
    height: 56px;
    padding: 0 10px;
    gap: 0;
    position: relative;
  }

  .mobile-menu-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    flex-shrink: 0;
    margin-right: 4px;
    transition: transform 0.3s ease;
    position: relative;
    z-index: 3;
    touch-action: manipulation;
  }

  .mobile-menu-btn.active {
    transform: rotate(90deg);
  }

  .mobile-menu-btn .feather {
    width: 22px;
    height: 22px;
  }

  .logo {
    display: flex;
    align-items: center;
    flex-shrink: 0;
    margin-right: auto;
  }

  .logo-text {
    font-size: 20px;
    line-height: 1;
  }

  /* Theme toggle — absolute right */
  .theme-toggle {
    position: absolute;
    right: 8px;
    top: 50%;
    transform: translateY(-50%);
    width: 40px;
    height: 40px;
    margin: 0;
    flex-shrink: 0;
    z-index: 2;
  }

  /* Hide desktop user-actions completely on mobile — everything is in burger menu */
  .user-actions {
    display: none;
  }

  /* Main nav = full dropdown from burger (animated) */
  .main-nav {
    display: flex;
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-color);
    flex-direction: column;
    padding: 20px 24px;
    gap: 14px;
    z-index: 998;
    overflow-y: auto;
    border-top: 1px solid var(--border-color);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);

    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(-12px);
    transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s;
  }

  .main-nav.active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
  }

  .main-nav a {
    font-size: 17px;
    font-weight: 500;
    color: var(--text-main);
    padding: 8px 0;
  }

  .main-nav a:hover {
    color: var(--accent-color);
  }

  .main-nav a.btn-primary {
    margin-top: 6px;
  }

  /* Show mobile-only elements */
  .nav-divider {
    display: block;
  }

  .nav-user-info {
    display: block;
  }

  .nav-logout-form {
    display: block;
  }

  .nav-login-link {
    display: block;
  }

  /* Other responsive */
  .courses-grid {
    grid-template-columns: 1fr;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .content-container {
    padding: 20px 16px;
  }

  .auth-container {
    margin: 30px auto;
    padding: 24px;
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .col-hide-mobile {
    display: none;
  }

  .data-table {
    font-size: 13px;
  }

  .data-table th,
  .data-table td {
    padding: 10px 12px;
  }

  .table-actions {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }

  .table-actions .btn-link-danger {
    margin: 0;
  }

  .hero-section {
    padding: 60px 16px 40px;
  }

  .hero-content h1 {
    font-size: 28px;
  }

  .hero-content p {
    font-size: 15px;
  }

  .hero-actions {
    flex-direction: column;
    gap: 12px;
    align-items: center;
  }
}

/* ==================================
   EXTRA SMALL SCREENS — ≤480px
   =================================== */
@media (max-width: 480px) {
  .header-container {
    height: 48px;
    padding: 0 8px;
  }

  .logo-text {
    font-size: 18px;
  }

  .mobile-menu-btn {
    width: 40px;
    height: 40px;
  }

  .mobile-menu-btn .feather {
    width: 20px;
    height: 20px;
  }

  .theme-toggle {
    width: 34px;
    height: 34px;
    right: 4px;
  }

  .theme-toggle .feather {
    width: 18px;
    height: 18px;
  }

  .main-nav {
    top: 48px;
    padding: 16px 18px;
    gap: 10px;
  }

  .main-nav a {
    font-size: 15px;
    padding: 6px 0;
  }

  .app-footer {
    padding: 18px 12px;
    margin-top: 40px;
  }

  .footer-container p {
    font-size: 12px;
  }

  .toast-container {
    right: 8px;
    left: 8px;
    top: 60px;
  }

  .toast {
    max-width: 100%;
    font-size: 13px;
    padding: 12px 14px;
  }
}

/* ==================================
   LESSON LAYOUT (Learn page)
=================================== */
.lesson-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 24px;
  align-items: flex-start;
}

.lesson-layout.preview-active {
  max-width: 1500px;
}

.lesson-sidebar {
  position: sticky;
  top: 90px;
}

.lesson-sidebar-cover {
  display: block;
  width: 100%;
  height: 120px;
  object-fit: cover;
  border-radius: 8px;
  margin-bottom: 14px;
}

.lesson-sidebar-toggle {
  display: none;
  width: 100%;
  padding: 10px 14px;
  font-size: 14px;
  font-weight: 600;
  background: var(--block-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  cursor: pointer;
  color: var(--text-main);
  font-family: var(--font-family-body);
  text-align: left;
  margin-bottom: 8px;
}

.lesson-sidebar-toggle::after {
  content: ' ▾';
  float: right;
  font-size: 12px;
}

.lesson-sidebar-toggle.open::after {
  content: ' ▴';
}

.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 20px;
}

@media (max-width: 900px) {
  .lesson-layout {
    grid-template-columns: 220px 1fr;
    gap: 20px;
  }

  .lesson-sidebar {
    font-size: 13px;
  }
}

@media (max-width: 768px) {
  .lesson-layout {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .lesson-sidebar-toggle {
    display: block;
  }

  .lesson-sidebar {
    display: none;
    position: static;
    margin-bottom: 16px;
  }

  .lesson-sidebar.open {
    display: block;
  }

  .lesson-nav {
    flex-direction: column;
    gap: 10px;
  }

  .lesson-nav .btn {
    width: 100%;
    text-align: center;
  }

  .content-container {
    padding: 16px 12px;
  }
}

@media (max-width: 480px) {
  .lesson-layout {
    gap: 12px;
  }

  .lesson-sidebar-toggle {
    font-size: 13px;
    padding: 8px 12px;
  }

  .lesson-sidebar {
    padding: 14px !important;
  }

  .lesson-sidebar h3 {
    font-size: 15px;
  }

  .content-container {
    padding: 12px 8px;
  }
}

/* ==================================
   DISCUSSIONS
=================================== */
.discussion-textarea {
  width: 100%;
  box-sizing: border-box;
  padding: 10px 12px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  font-family: inherit;
  font-size: 14px;
  line-height: 1.5;
  resize: vertical;
  background: var(--input-bg, #fff);
  color: var(--text-main);
}

.discussion-textarea:focus {
  outline: none;
  border-color: var(--accent-color);
}

.discussion-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.discussion-item {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 14px 16px;
}

.discussion-item.discussion-reply {
  margin-top: 12px;
  margin-left: 24px;
  border-left: 3px solid var(--accent-color);
  background: var(--block-bg);
}

.discussion-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-bottom: 6px;
}

.discussion-author {
  font-weight: 600;
  font-size: 14px;
}

.discussion-date {
  color: var(--text-muted);
  font-size: 12px;
}

.discussion-body {
  font-size: 14px;
  line-height: 1.6;
  white-space: normal;
  word-wrap: break-word;
}

.discussion-actions {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-top: 8px;
}

.discussion-reply-btn,
.discussion-delete-btn {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  font-size: 13px;
  font-family: inherit;
}

.discussion-reply-btn {
  color: var(--accent-color);
}

.discussion-delete-btn {
  color: #dc2626;
}

.discussion-reply-btn:hover,
.discussion-delete-btn:hover {
  text-decoration: underline;
}

.discussion-reply-form {
  margin-top: 12px;
}

/* ==================================
   SUBMISSIONS / ASSIGNMENTS
=================================== */
.submission-card {
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--border-color);
  border-radius: 8px;
  padding: 14px 16px;
  background: var(--block-bg);
}

.submission-card.pending { border-left-color: #d97706; }
.submission-card.passed  { border-left-color: #059669; }
.submission-card.failed  { border-left-color: #dc2626; }

.submission-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.submission-status-badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  color: #fff;
}

.submission-status-badge.pending { background: #d97706; }
.submission-status-badge.passed  { background: #059669; }
.submission-status-badge.failed  { background: #dc2626; }

.submission-file {
  font-size: 14px;
  font-weight: 500;
}

.submission-date {
  color: var(--text-muted);
  font-size: 12px;
}

.submission-preview-frame {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  margin: 4px 0 12px;
  overflow: hidden;
  background: #fff;
}

.submission-preview-iframe {
  display: block;
  width: 100%;
  height: 70vh;
  min-height: 480px;
  border: none;
  background: #fff;
}

.submission-comment,
.submission-feedback {
  font-size: 14px;
  line-height: 1.5;
  margin-top: 10px;
}

.submission-grade {
  font-size: 15px;
  margin-top: 10px;
}

/* ==================================
   MESSAGES (private threads)
=================================== */
.msg-thread {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 20px;
}

.msg-bubble {
  max-width: 75%;
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid var(--border-color);
}

.msg-bubble.theirs {
  align-self: flex-start;
  background: var(--block-bg);
  border-bottom-left-radius: 2px;
}

.msg-bubble.mine {
  align-self: flex-end;
  background: var(--accent-color);
  border-color: var(--accent-color);
  color: #fff;
  border-bottom-right-radius: 2px;
}

.msg-body {
  font-size: 14px;
  line-height: 1.5;
  word-wrap: break-word;
}

.msg-time {
  font-size: 11px;
  opacity: 0.7;
  margin-top: 4px;
  text-align: right;
}

.msg-form {
  margin-top: 8px;
}

/* ==================================
   ADMIN PANEL
=================================== */
.admin-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

.admin-section-title {
  font-size: 18px;
  margin: 24px 0 12px;
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 14px;
}

.stat-card {
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 18px 16px;
  background: var(--block-bg);
  text-align: center;
}

.stat-value {
  font-size: 30px;
  font-weight: 700;
  line-height: 1.1;
}

.stat-label {
  color: var(--text-muted);
  font-size: 13px;
  margin-top: 6px;
}

.admin-select {
  padding: 5px 8px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: var(--block-bg);
  color: var(--text-main);
  font-size: 13px;
}
/* ===== Lesson content (Markdown) ===== */
.lesson-markdown {
  --code-bg: #F3F6F9;
  --code-inline-bg: rgba(21, 34, 45, 0.07);
  line-height: 1.7;
  overflow-wrap: break-word;
}

[data-theme="dark"] .lesson-markdown {
  --code-bg: #0B1218;
  --code-inline-bg: rgba(232, 238, 244, 0.1);
}

.lesson-markdown > :first-child { margin-top: 0; }
.lesson-markdown > :last-child { margin-bottom: 0; }
.lesson-markdown h1, .lesson-markdown h2, .lesson-markdown h3, .lesson-markdown h4 {
  font-family: var(--font-family-display);
  line-height: 1.3;
  margin: 1.6em 0 0.6em;
}
.lesson-markdown h1 { font-size: 1.75em; }
.lesson-markdown h2 { font-size: 1.4em; padding-bottom: 0.3em; border-bottom: 1px solid var(--border-color); }
.lesson-markdown h3 { font-size: 1.2em; }
.lesson-markdown p, .lesson-markdown ul, .lesson-markdown ol,
.lesson-markdown blockquote, .lesson-markdown table, .lesson-markdown pre { margin: 0 0 1em; }
.lesson-markdown ul, .lesson-markdown ol { padding-left: 1.6em; }
.lesson-markdown li + li { margin-top: 0.25em; }
.lesson-markdown li > input[type="checkbox"] { margin-right: 6px; }
.lesson-markdown a { color: var(--accent-color); }
.lesson-markdown img { max-width: 100%; border-radius: 8px; }
.lesson-markdown hr { border: 0; border-top: 1px solid var(--border-color); margin: 2em 0; }
.lesson-markdown blockquote {
  padding: 0.5em 1em;
  border-left: 4px solid var(--accent-color);
  background: var(--block-bg);
  color: var(--text-muted);
  border-radius: 0 6px 6px 0;
}
.lesson-markdown blockquote > :last-child { margin-bottom: 0; }
.lesson-markdown table { border-collapse: collapse; display: block; overflow-x: auto; max-width: 100%; }
.lesson-markdown th, .lesson-markdown td { border: 1px solid var(--border-color); padding: 6px 12px; text-align: left; }
.lesson-markdown th { background: var(--block-bg); font-weight: 600; }

.lesson-markdown code {
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
}
.lesson-markdown :not(pre) > code {
  background: var(--code-inline-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
}
.lesson-markdown pre {
  position: relative;
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 14px 16px;
  overflow-x: auto;
  line-height: 1.55;
  tab-size: 4;
}
.lesson-markdown pre code { background: none; padding: 0; font-size: 13.5px; }

.code-copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  padding: 3px 10px;
  font-size: 12px;
  font-family: var(--font-family-body);
  color: var(--text-muted);
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s ease;
}
.lesson-markdown pre:hover .code-copy-btn,
.code-copy-btn:focus-visible { opacity: 1; }
@media (hover: none) { .code-copy-btn { opacity: 1; } }

/* highlight.js tokens — light */
.hljs-comment, .hljs-quote { color: #6A737D; font-style: italic; }
.hljs-keyword, .hljs-selector-tag, .hljs-literal, .hljs-doctag, .hljs-meta .hljs-keyword { color: #CF222E; }
.hljs-string, .hljs-regexp, .hljs-addition, .hljs-meta .hljs-string { color: #0A3069; }
.hljs-number, .hljs-symbol, .hljs-bullet, .hljs-variable.constant_ { color: #0550AE; }
.hljs-title, .hljs-title.function_, .hljs-section { color: #8250DF; }
.hljs-title.class_, .hljs-type, .hljs-built_in { color: #953800; }
.hljs-attr, .hljs-attribute, .hljs-property, .hljs-variable, .hljs-template-variable, .hljs-params { color: #116329; }
.hljs-name, .hljs-tag { color: #116329; }
.hljs-meta { color: #6E7781; }
.hljs-deletion { color: #82071E; background: #FFEBE9; }
.hljs-addition { background: #DAFBE1; }
.hljs-emphasis { font-style: italic; }
.hljs-strong { font-weight: 700; }

/* highlight.js tokens — dark */
[data-theme="dark"] .hljs-comment, [data-theme="dark"] .hljs-quote { color: #8B949E; }
[data-theme="dark"] .hljs-keyword, [data-theme="dark"] .hljs-selector-tag, [data-theme="dark"] .hljs-literal,
[data-theme="dark"] .hljs-doctag, [data-theme="dark"] .hljs-meta .hljs-keyword { color: #FF7B72; }
[data-theme="dark"] .hljs-string, [data-theme="dark"] .hljs-regexp, [data-theme="dark"] .hljs-meta .hljs-string { color: #A5D6FF; }
[data-theme="dark"] .hljs-number, [data-theme="dark"] .hljs-symbol, [data-theme="dark"] .hljs-bullet,
[data-theme="dark"] .hljs-variable.constant_ { color: #79C0FF; }
[data-theme="dark"] .hljs-title, [data-theme="dark"] .hljs-title.function_, [data-theme="dark"] .hljs-section { color: #D2A8FF; }
[data-theme="dark"] .hljs-title.class_, [data-theme="dark"] .hljs-type, [data-theme="dark"] .hljs-built_in { color: #FFA657; }
[data-theme="dark"] .hljs-attr, [data-theme="dark"] .hljs-attribute, [data-theme="dark"] .hljs-property,
[data-theme="dark"] .hljs-variable, [data-theme="dark"] .hljs-template-variable, [data-theme="dark"] .hljs-params,
[data-theme="dark"] .hljs-name, [data-theme="dark"] .hljs-tag { color: #7EE787; }
[data-theme="dark"] .hljs-meta { color: #8B949E; }
[data-theme="dark"] .hljs-deletion { color: #FFDCD7; background: #67060C; }
[data-theme="dark"] .hljs-addition { color: #AFF5B4; background: #033A16; }