/* Web3 Senior DevBook - Modern Cyberpunk / Linear Style CSS */
:root {
  --bg-primary: #0a0d16;
  --bg-secondary: #111726;
  --bg-card: #151d30;
  --bg-hover: #1c263d;
  --border: #232f48;
  --border-focus: #3b82f6;
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --accent-cyan: #06b6d4;
  --accent-blue: #3b82f6;
  --accent-purple: #8b5cf6;
  --accent-emerald: #10b981;
  --accent-rose: #f43f5e;
  --accent-amber: #f59e0b;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  --header-height: 64px;
  --sidebar-width: 280px;
  --toc-width: 240px;
}

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

body {
  background-color: var(--bg-primary);
  color: var(--text-main);
  font-family: var(--font-sans);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary);
}
::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent-cyan);
}

/* Header */
header.app-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(10, 13, 22, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  z-index: 100;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
}

.brand-icon {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-purple));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 900;
  font-size: 18px;
  color: #fff;
  box-shadow: 0 0 15px rgba(6, 182, 212, 0.4);
}

.brand-text h1 {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.5px;
  background: linear-gradient(90deg, #fff, #93c5fd);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-text span {
  font-size: 11px;
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  text-transform: uppercase;
}

.nav-tabs {
  display: flex;
  gap: 6px;
  background: var(--bg-secondary);
  padding: 4px;
  border-radius: 10px;
  border: 1px solid var(--border);
}

.nav-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-btn:hover {
  color: #fff;
  background: var(--bg-hover);
}

.nav-btn.active {
  color: #fff;
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.2), rgba(59, 130, 246, 0.2));
  border: 1px solid rgba(6, 182, 212, 0.5);
  box-shadow: 0 0 10px rgba(6, 182, 212, 0.2);
}

.header-right {
  display: flex;
  align-items: center;
  gap: 16px;
}

.search-box {
  position: relative;
  display: flex;
  align-items: center;
}

.search-input {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 12px 6px 34px;
  color: var(--text-main);
  font-size: 13px;
  width: 240px;
  transition: all 0.2s ease;
}

.search-input:focus {
  outline: none;
  border-color: var(--accent-cyan);
  width: 320px;
  box-shadow: 0 0 12px rgba(6, 182, 212, 0.25);
}

.search-icon {
  position: absolute;
  left: 10px;
  color: var(--text-dim);
  font-size: 14px;
  pointer-events: none;
}

.kbd-shortcut {
  position: absolute;
  right: 8px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  padding: 2px 5px;
  border-radius: 4px;
  font-size: 10px;
  color: var(--text-dim);
  font-family: var(--font-mono);
}

/* App Container Layout */
.app-container {
  display: flex;
  margin-top: var(--header-height);
  min-height: calc(100vh - var(--header-height));
}

/* Sidebar */
aside.app-sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  position: fixed;
  top: var(--header-height);
  bottom: 0;
  left: 0;
  overflow-y: auto;
  padding: 20px 12px;
  z-index: 50;
}

.sidebar-title {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-dim);
  padding: 0 10px 8px;
  font-weight: 700;
}

.module-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.module-nav-item {
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 13px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all 0.2s;
  border: 1px solid transparent;
}

.module-nav-item:hover {
  background: var(--bg-hover);
  color: #fff;
}

.module-nav-item.active {
  background: var(--bg-card);
  color: var(--accent-cyan);
  border-color: rgba(6, 182, 212, 0.3);
  font-weight: 600;
}

.badge {
  font-size: 10px;
  padding: 2px 6px;
  border-radius: 10px;
  background: rgba(6, 182, 212, 0.15);
  color: var(--accent-cyan);
  border: 1px solid rgba(6, 182, 212, 0.3);
  font-family: var(--font-mono);
}

/* Main Content Area */
main.app-main {
  margin-left: var(--sidebar-width);
  flex: 1;
  padding: 32px 48px;
  max-width: 1020px;
  min-height: 100vh;
}

/* Right TOC */
aside.app-toc {
  width: var(--toc-width);
  position: fixed;
  top: calc(var(--header-height) + 32px);
  right: 24px;
  display: none;
}

@media (min-width: 1400px) {
  aside.app-toc {
    display: block;
  }
}

.toc-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-dim);
  letter-spacing: 0.5px;
  margin-bottom: 12px;
}

.toc-list {
  list-style: none;
  border-left: 1px solid var(--border);
  padding-left: 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toc-item a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 12px;
  display: block;
  transition: color 0.2s;
  line-height: 1.4;
}

.toc-item a:hover {
  color: var(--accent-cyan);
}

/* Module Banner */
.module-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border);
}

.module-badge-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
}

.module-title {
  font-size: 28px;
  font-weight: 800;
  letter-spacing: -0.5px;
  color: #fff;
  margin-bottom: 8px;
}

.module-desc {
  font-size: 15px;
  color: var(--text-muted);
  max-width: 800px;
}

/* Section Card */
.section-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px;
  margin-bottom: 28px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

.section-card h2 {
  font-size: 20px;
  font-weight: 700;
  color: #fff;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.section-card h3 {
  font-size: 16px;
  font-weight: 600;
  color: #e2e8f0;
  margin: 20px 0 10px;
}

.section-card p {
  color: var(--text-muted);
  font-size: 14px;
  margin-bottom: 14px;
  line-height: 1.7;
}

.section-card ul, .section-card ol {
  color: var(--text-muted);
  font-size: 14px;
  padding-left: 20px;
  margin-bottom: 16px;
  line-height: 1.7;
}

.section-card li {
  margin-bottom: 6px;
}

/* Tech Box / Tables */
.tech-box {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px;
  margin: 18px 0;
}

.tech-box h4 {
  color: var(--accent-cyan);
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 10px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 8px;
}

th, td {
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: rgba(255, 255, 255, 0.03);
  color: #fff;
  font-weight: 600;
}

tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

/* Code Header & Blocks */
.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: #1e293b;
  padding: 8px 16px;
  border-top-left-radius: 8px;
  border-top-right-radius: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-dim);
  border-left: 1px solid var(--border);
  border-right: 1px solid var(--border);
  border-top: 1px solid var(--border);
}

.copy-btn {
  background: var(--bg-hover);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 3px 8px;
  border-radius: 4px;
  font-size: 11px;
  cursor: pointer;
  transition: all 0.2s;
}

.copy-btn:hover {
  color: #fff;
  border-color: var(--accent-cyan);
}

pre {
  background: #0f172a;
  border: 1px solid var(--border);
  border-bottom-left-radius: 8px;
  border-bottom-right-radius: 8px;
  padding: 16px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.5;
  margin-bottom: 18px;
  color: #e2e8f0;
}

code {
  font-family: var(--font-mono);
}

p code, li code {
  background: rgba(59, 130, 246, 0.15);
  color: #93c5fd;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 12px;
  border: 1px solid rgba(59, 130, 246, 0.25);
}

/* Question Bank Cards */
.filter-bar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.filter-chip {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 12px;
  cursor: pointer;
  transition: all 0.2s;
}

.filter-chip:hover, .filter-chip.active {
  background: var(--accent-cyan);
  color: #000;
  font-weight: 600;
  border-color: var(--accent-cyan);
}

.question-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 18px;
  overflow: hidden;
  transition: all 0.2s;
}

.question-card:hover {
  border-color: rgba(6, 182, 212, 0.4);
}

.question-header {
  padding: 20px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.q-left {
  flex: 1;
}

.q-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}

.q-cat {
  font-size: 11px;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 4px;
  background: rgba(139, 92, 246, 0.15);
  color: var(--accent-purple);
  border: 1px solid rgba(139, 92, 246, 0.3);
}

.q-diff {
  font-size: 11px;
  padding: 2px 6px;
  border-radius: 4px;
  font-weight: 600;
}
.q-diff.Medium { background: rgba(245, 158, 11, 0.15); color: var(--accent-amber); }
.q-diff.Hard { background: rgba(244, 63, 94, 0.15); color: var(--accent-rose); }
.q-diff.Expert { background: rgba(16, 185, 129, 0.15); color: var(--accent-emerald); }

.q-title {
  font-size: 15px;
  font-weight: 600;
  color: #fff;
  line-height: 1.5;
}

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

.toggle-arrow {
  color: var(--text-dim);
  font-size: 18px;
  transition: transform 0.2s;
}

.question-card.open .toggle-arrow {
  transform: rotate(180deg);
  color: var(--accent-cyan);
}

.question-body {
  display: none;
  padding: 0 20px 20px;
  border-top: 1px solid var(--border);
  background: rgba(15, 23, 42, 0.5);
}

.question-card.open .question-body {
  display: block;
}

/* Mind Map Viewer */
.mindmap-wrapper {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  min-height: 600px;
  display: flex;
  flex-direction: column;
}

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

.mindmap-container {
  flex: 1;
  overflow: auto;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #090d16;
  border-radius: 8px;
  padding: 20px;
}

/* Responsive */
@media (max-width: 900px) {
  aside.app-sidebar {
    transform: translateX(-100%);
    transition: transform 0.3s ease;
  }
  aside.app-sidebar.open {
    transform: translateX(0);
  }
  main.app-main {
    margin-left: 0;
    padding: 20px;
  }
  .search-input {
    width: 140px;
  }
  .search-input:focus {
    width: 200px;
  }
}