/* === CSS Variables === */
:root {
  --bg-primary: #0a0e14;
  --bg-secondary: #0d1117;
  --bg-tertiary: #161b22;
  --bg-code: #1a1e24;
  --border-color: #30363d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --text-heading: #f0f6fc;
  --accent-green: #3fb950;
  --accent-blue: #58a6ff;
  --accent-orange: #d29922;
  --accent-red: #f85149;
  --accent-purple: #bc8cff;
  --accent-cyan: #39d2c0;
  --accent-yellow: #e3b341;
  --font-mono: 'Cascadia Code', 'Fira Code', 'JetBrains Mono', 'Consolas', 'Courier New', monospace;
  --font-size-base: 14px;
  --font-size-sm: 12px;
  --font-size-lg: 16px;
  --font-size-xl: 20px;
  --font-size-xxl: 28px;
  --sidebar-width: 300px;
  --header-height: 56px;
  --transition-speed: 0.25s;
}

/* === Reset & Base === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: var(--font-size-base);
}

body {
  font-family: var(--font-mono);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

::selection {
  background-color: var(--accent-blue);
  color: var(--bg-primary);
}

/* === Scrollbar === */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-secondary);
}

/* === Layout === */
.app-layout {
  display: flex;
  min-height: 100vh;
}

/* === Sidebar === */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  position: fixed;
  top: 0;
  left: 0;
  height: 100vh;
  overflow-y: auto;
  z-index: 100;
  transition: transform var(--transition-speed) ease;
  display: flex;
  flex-direction: column;
}

.sidebar-header {
  padding: 16px 20px;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  background-color: var(--bg-secondary);
  z-index: 10;
}

.sidebar-title {
  font-size: var(--font-size-lg);
  color: var(--accent-green);
  font-weight: 700;
  letter-spacing: 0.5px;
}

.sidebar-title .prompt {
  color: var(--accent-orange);
  margin-right: 6px;
}

.sidebar-subtitle {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin-top: 4px;
}

/* === Search === */
.sidebar-search {
  padding: 12px 20px;
  border-bottom: 1px solid var(--border-color);
}

.sidebar-search input {
  width: 100%;
  padding: 8px 12px;
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  outline: none;
  transition: border-color var(--transition-speed);
}

.sidebar-search input::placeholder {
  color: var(--text-secondary);
}

.sidebar-search input:focus {
  border-color: var(--accent-blue);
  box-shadow: 0 0 0 2px rgba(88, 166, 255, 0.15);
}

/* === Navigation === */
.sidebar-nav {
  flex: 1;
  padding: 12px 0;
  overflow-y: auto;
}

.nav-section {
  margin-bottom: 8px;
}

.nav-section-title {
  padding: 8px 20px;
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
}

.nav-item {
  display: block;
  padding: 6px 20px 6px 28px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: var(--font-size-sm);
  transition: all var(--transition-speed);
  border-left: 2px solid transparent;
  cursor: pointer;
}

.nav-item:hover {
  color: var(--text-primary);
  background-color: rgba(88, 166, 255, 0.05);
  border-left-color: var(--accent-blue);
}

.nav-item.active {
  color: var(--accent-green);
  background-color: rgba(63, 185, 80, 0.08);
  border-left-color: var(--accent-green);
  font-weight: 600;
}

.nav-item .nav-priority {
  display: inline-block;
  padding: 1px 6px;
  border-radius: 3px;
  font-size: 10px;
  margin-left: 8px;
  font-weight: 700;
  text-transform: uppercase;
}

.nav-priority.critical {
  background-color: rgba(248, 81, 73, 0.15);
  color: var(--accent-red);
}

.nav-priority.high {
  background-color: rgba(210, 153, 34, 0.15);
  color: var(--accent-orange);
}

.nav-priority.medium {
  background-color: rgba(88, 166, 255, 0.15);
  color: var(--accent-blue);
}

/* === Mobile Toggle === */
.sidebar-toggle {
  display: none;
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 200;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  padding: 8px 12px;
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  transition: background-color var(--transition-speed);
}

.sidebar-toggle:hover {
  background-color: var(--border-color);
}

.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.6);
  z-index: 90;
}

/* === Main Content === */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-width: 0;
}

/* === Content Header === */
.content-header {
  padding: 24px 40px;
  border-bottom: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  position: sticky;
  top: 0;
  z-index: 50;
}

.breadcrumb {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.breadcrumb a {
  color: var(--accent-blue);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb .separator {
  margin: 0 8px;
  color: var(--text-secondary);
}

.content-title {
  font-size: var(--font-size-xxl);
  color: var(--text-heading);
  font-weight: 700;
  line-height: 1.3;
}

.content-title .module-badge {
  display: inline-block;
  padding: 2px 10px;
  background-color: rgba(63, 185, 80, 0.15);
  color: var(--accent-green);
  border-radius: 4px;
  font-size: var(--font-size-sm);
  margin-right: 12px;
  vertical-align: middle;
  font-weight: 600;
}

/* === Content Body === */
.content-body {
  padding: 32px 40px 80px;
  max-width: 900px;
}

/* === Terminal Prompt Decoration === */
.content-body::before {
  content: '$ cat module.md';
  display: block;
  color: var(--accent-orange);
  font-size: var(--font-size-sm);
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 1px dashed var(--border-color);
}

/* === Headings === */
.content-body h1 {
  font-size: var(--font-size-xxl);
  color: var(--text-heading);
  margin: 40px 0 20px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-color);
}

.content-body h1:first-child {
  margin-top: 0;
}

.content-body h2 {
  font-size: var(--font-size-xl);
  color: var(--accent-cyan);
  margin: 36px 0 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.content-body h3 {
  font-size: var(--font-size-lg);
  color: var(--accent-green);
  margin: 28px 0 12px;
}

.content-body h4 {
  font-size: var(--font-size-base);
  color: var(--accent-purple);
  margin: 20px 0 10px;
}

.content-body h5, .content-body h6 {
  font-size: var(--font-size-base);
  color: var(--text-secondary);
  margin: 16px 0 8px;
}

/* === Paragraphs === */
.content-body p {
  margin-bottom: 16px;
  color: var(--text-primary);
}

/* === Links === */
.content-body a {
  color: var(--accent-blue);
  text-decoration: none;
  border-bottom: 1px dashed var(--accent-blue);
  transition: all var(--transition-speed);
}

.content-body a:hover {
  color: var(--accent-cyan);
  border-bottom-color: var(--accent-cyan);
}

/* === Code === */
.content-body code {
  font-family: var(--font-mono);
  background-color: var(--bg-code);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
  color: var(--accent-orange);
  border: 1px solid var(--border-color);
}

.content-body pre {
  background-color: var(--bg-code);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 16px 20px;
  margin: 20px 0;
  overflow-x: auto;
  position: relative;
}

.content-body pre code {
  background-color: transparent;
  padding: 0;
  border: none;
  color: var(--text-primary);
  font-size: var(--font-size-sm);
  line-height: 1.6;
}

.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 16px;
  background-color: var(--bg-tertiary);
  border-bottom: 1px solid var(--border-color);
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  border-radius: 8px 8px 0 0;
}

.content-body pre.with-header {
  padding: 0;
  margin: 20px 0;
}

.content-body pre.with-header code {
  padding: 16px 20px;
}

/* === Blockquotes === */
.content-body blockquote {
  border-left: 3px solid var(--accent-blue);
  padding: 12px 20px;
  margin: 20px 0;
  background-color: rgba(88, 166, 255, 0.05);
  border-radius: 0 6px 6px 0;
}

.content-body blockquote p {
  margin-bottom: 0;
  color: var(--text-secondary);
}

.content-body blockquote.warning {
  border-left-color: var(--accent-orange);
  background-color: rgba(210, 153, 34, 0.05);
}

.content-body blockquote.critical {
  border-left-color: var(--accent-red);
  background-color: rgba(248, 81, 73, 0.05);
}

.content-body blockquote.info {
  border-left-color: var(--accent-cyan);
  background-color: rgba(57, 210, 192, 0.05);
}

/* === Tables === */
.content-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: var(--font-size-sm);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  overflow: hidden;
}

.content-body thead {
  background-color: var(--bg-tertiary);
}

.content-body th {
  padding: 10px 16px;
  text-align: left;
  color: var(--accent-cyan);
  font-weight: 600;
  border-bottom: 2px solid var(--border-color);
  white-space: nowrap;
}

.content-body td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-primary);
  vertical-align: top;
}

.content-body tbody tr:hover {
  background-color: rgba(88, 166, 255, 0.03);
}

.content-body tbody tr:last-child td {
  border-bottom: none;
}

/* === Lists === */
.content-body ul, .content-body ol {
  margin: 16px 0;
  padding-left: 24px;
}

.content-body li {
  margin-bottom: 8px;
  color: var(--text-primary);
}

.content-body ul li::marker {
  color: var(--accent-green);
}

.content-body ol li::marker {
  color: var(--accent-orange);
}

.content-body ul ul, .content-body ol ol {
  margin-top: 8px;
  margin-bottom: 8px;
}

/* === Checkboxes === */
.content-body input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border: 1px solid var(--border-color);
  border-radius: 3px;
  background-color: var(--bg-primary);
  cursor: pointer;
  vertical-align: middle;
  margin-right: 8px;
  position: relative;
}

.content-body input[type="checkbox"]:checked {
  background-color: var(--accent-green);
  border-color: var(--accent-green);
}

.content-body input[type="checkbox"]:checked::after {
  content: '\2713';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: var(--bg-primary);
  font-size: 11px;
  font-weight: 700;
}

.checkbox-label {
  display: inline;
  cursor: pointer;
}

/* === Horizontal Rule === */
.content-body hr {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 32px 0;
}

/* === Tags / Badges === */
.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: var(--font-size-sm);
  font-weight: 600;
}

.badge-foundation {
  background-color: rgba(88, 166, 255, 0.15);
  color: var(--accent-blue);
}

.badge-advanced {
  background-color: rgba(188, 140, 255, 0.15);
  color: var(--accent-purple);
}

.badge-expert {
  background-color: rgba(248, 81, 73, 0.15);
  color: var(--accent-red);
}

.badge-phase {
  background-color: rgba(63, 185, 80, 0.15);
  color: var(--accent-green);
}

/* === Phase Timeline === */
.phase-timeline {
  margin: 24px 0;
  padding: 0;
  list-style: none;
}

.phase-timeline li {
  padding: 12px 16px;
  margin-bottom: 8px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  border-left: 3px solid var(--accent-blue);
}

.phase-timeline .phase-label {
  color: var(--accent-green);
  font-weight: 700;
  margin-right: 8px;
}

.phase-timeline .phase-desc {
  color: var(--text-secondary);
}

.phase-timeline .phase-modules {
  color: var(--accent-orange);
  margin-left: 8px;
}

/* === Module Grid (Home) === */
.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin: 24px 0;
}

.module-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 16px 20px;
  text-decoration: none;
  transition: all var(--transition-speed);
  cursor: pointer;
  display: block;
}

.module-card:hover {
  border-color: var(--accent-blue);
  background-color: var(--bg-tertiary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.module-card .card-number {
  display: inline-block;
  padding: 2px 8px;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  font-size: var(--font-size-sm);
  color: var(--accent-green);
  font-weight: 700;
  margin-bottom: 8px;
}

.module-card .card-title {
  font-size: var(--font-size-base);
  color: var(--text-heading);
  font-weight: 600;
  margin-bottom: 6px;
}

.module-card .card-desc {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  line-height: 1.5;
}

.module-card .card-priority {
  display: inline-block;
  margin-top: 8px;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* === Back to Top === */
.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--accent-green);
  padding: 10px 16px;
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-speed);
  z-index: 80;
  text-decoration: none;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background-color: var(--border-color);
  transform: translateY(-2px);
}

/* === Footer === */
.content-footer {
  padding: 24px 40px;
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  text-align: center;
}

/* === Responsive === */
@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .sidebar-toggle {
    display: block;
  }

  .overlay.active {
    display: block;
  }

  .main-content {
    margin-left: 0;
  }

  .content-header,
  .content-body,
  .content-footer {
    padding-left: 24px;
    padding-right: 24px;
  }
}

@media (max-width: 640px) {
  :root {
    --font-size-base: 13px;
    --font-size-xxl: 22px;
    --font-size-xl: 17px;
  }

  .content-body {
    padding-left: 16px;
    padding-right: 16px;
  }

  .content-header,
  .content-footer {
    padding-left: 16px;
    padding-right: 16px;
  }

  .module-grid {
    grid-template-columns: 1fr;
  }

  .content-body table {
    display: block;
    overflow-x: auto;
  }
}

/* === Print === */
@media print {
  .sidebar,
  .sidebar-toggle,
  .back-to-top {
    display: none !important;
  }

  .main-content {
    margin-left: 0;
  }

  body {
    background-color: #fff;
    color: #000;
  }
}

/* === Animations === */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.content-body > * {
  animation: fadeIn 0.3s ease;
}

/* === Level Section Divider === */
.level-divider {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 40px 0 24px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.level-divider .level-badge {
  padding: 4px 12px;
  border-radius: 4px;
  font-size: var(--font-size-sm);
  font-weight: 700;
  white-space: nowrap;
}

.level-divider .level-line {
  flex: 1;
  height: 1px;
  background: linear-gradient(to right, var(--border-color), transparent);
}

.level-1 .level-badge {
  background-color: rgba(88, 166, 255, 0.15);
  color: var(--accent-blue);
}

.level-2 .level-badge {
  background-color: rgba(188, 140, 255, 0.15);
  color: var(--accent-purple);
}

.level-3 .level-badge {
  background-color: rgba(248, 81, 73, 0.15);
  color: var(--accent-red);
}

/* === Project Box === */
.project-box {
  background-color: var(--bg-secondary);
  border: 1px solid var(--accent-green);
  border-radius: 8px;
  padding: 20px 24px;
  margin: 24px 0;
}

.project-box .project-title {
  color: var(--accent-green);
  font-size: var(--font-size-lg);
  font-weight: 700;
  margin-bottom: 12px;
}

.project-box .criteria {
  margin-top: 12px;
}

.project-box .criteria-title {
  color: var(--accent-orange);
  font-weight: 600;
  margin-bottom: 8px;
}

/* === Navigation Footer (prev/next) === */
.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  gap: 16px;
}

.page-nav a {
  flex: 1;
  padding: 12px 16px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--accent-blue);
  text-decoration: none;
  font-size: var(--font-size-sm);
  transition: all var(--transition-speed);
  max-width: 48%;
}

.page-nav a:hover {
  border-color: var(--accent-blue);
  background-color: var(--bg-tertiary);
}

.page-nav a.nav-next {
  text-align: right;
  margin-left: auto;
}

.page-nav .nav-label {
  display: block;
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  margin-bottom: 4px;
}

.page-nav .nav-title {
  color: var(--text-heading);
  font-weight: 600;
}