/* static/css/main.css */

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-mono);
  font-size: 15px;
  line-height: 1.9;
  color: var(--text-primary);
  background: var(--bg-primary);
  min-height: 100vh;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 4vw, 2.5rem); }
h3 { font-size: clamp(1.2rem, 3vw, 1.8rem); }

a {
  color: var(--accent-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* Progress Bar */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
  z-index: 10000;
  width: 0%;
  transition: width 0.1s;
}

/* Navigation */
.main-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(10, 10, 11, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.2rem;
  color: var(--text-primary);
}

.logo-icon {
  color: var(--accent-primary);
  font-size: 1.4rem;
}

.logo-text {
  color: var(--text-primary);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 0.5rem;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.5rem 1rem;
  border: 1px solid transparent;
  transition: all 0.2s;
}

.nav-links a:hover {
  color: var(--accent-primary);
  border-color: var(--accent-primary);
  text-decoration: none;
}

/* Main Content */
.main-content {
  padding-top: var(--nav-height);
  min-height: 100vh;
}

.main-content.with-sidebar {
  margin-left: var(--sidebar-width);
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

/* Sidebar */
.sidebar {
  position: fixed;
  top: var(--nav-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--nav-height));
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  overflow-y: auto;
  z-index: 100;
}

.sidebar-content {
  padding: 1.5rem;
}

.sidebar-section {
  margin-bottom: 2rem;
}

.sidebar-title {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.sidebar-list {
  list-style: none;
}

.sidebar-list li {
  margin-bottom: 0.25rem;
}

.sidebar-list a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.5rem;
  color: var(--text-secondary);
  font-size: 0.85rem;
  border-left: 3px solid transparent;
  transition: all 0.2s;
}

.sidebar-list a:hover,
.sidebar-list li.active a {
  color: var(--text-primary);
  background: var(--bg-tertiary);
  border-left-color: var(--accent-primary);
  text-decoration: none;
}

.sidebar-list .chapter-num {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--accent-primary);
  min-width: 1.5rem;
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 2rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.breadcrumb a {
  color: var(--text-secondary);
}

.breadcrumb .current {
  color: var(--text-primary);
}

.breadcrumb .separator {
  color: var(--text-muted);
}

/* Chapter Header */
.chapter-header {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 2px solid var(--border-color);
  position: relative;
}

.chapter-header::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100px;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
}

.chapter-number {
  font-family: var(--font-display);
  font-size: 6rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: 1rem;
  opacity: 0.9;
}

.chapter-header h1 {
  margin-bottom: 1rem;
  font-size: clamp(1.8rem, 4vw, 2.8rem);
}

.chapter-description {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.8;
  max-width: 80%;
}

/* Chapter Content */
.chapter-content {
  margin-bottom: 4rem;
}

.chapter-content h2 {
  margin-top: 3rem;
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}

.chapter-content h3 {
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  color: var(--accent-secondary);
}

.chapter-content p {
  margin-bottom: 1.75rem;
  color: var(--text-secondary);
  line-height: 1.9;
}

.chapter-content ul,
.chapter-content ol {
  margin-bottom: 1.75rem;
  padding-left: 2rem;
  line-height: 1.9;
}

.chapter-content li {
  margin-bottom: 0.75rem;
  color: var(--text-secondary);
  line-height: 1.9;
}

.chapter-content code {
  background: var(--bg-tertiary);
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
  font-size: 0.9em;
  color: var(--accent-primary);
}

/* Chapter Navigation */
.chapter-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  padding-top: 3rem;
  border-top: 2px solid var(--border-color);
}

.chapter-nav a {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.chapter-nav a::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: linear-gradient(180deg, var(--accent-primary), var(--accent-secondary));
  transform: scaleY(0);
  transition: transform 0.3s;
}

.chapter-nav a:hover {
  border-color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
  text-decoration: none;
}

.chapter-nav a:hover::before {
  transform: scaleY(1);
}

.chapter-nav .next {
  text-align: right;
  grid-column: 2;
}

.chapter-nav .next::before {
  left: auto;
  right: 0;
}

.chapter-nav .label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  transition: color 0.2s;
}

.chapter-nav a:hover .label {
  color: var(--accent-primary);
}

.chapter-nav .title {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--text-primary);
  transition: color 0.2s;
}

.chapter-nav a:hover .title {
  color: var(--accent-primary);
}

/* Footer */
.main-footer {
  margin-left: var(--sidebar-width);
  padding: 4rem 2rem;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  text-align: center;
}

.footer-logo {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--accent-primary);
  margin-bottom: 1rem;
}

.footer-text {
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.footer-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 4rem 0;
}

.hero-badge {
  display: inline-block;
  background: var(--bg-tertiary);
  border: 1px solid var(--accent-primary);
  color: var(--accent-primary);
  padding: 0.5rem 1rem;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 2rem;
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  margin-bottom: 1.5rem;
}

.hero h1 span {
  color: var(--accent-primary);
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 700px;
  margin: 0 auto 2rem;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-bottom: 4rem;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 4rem;
}

.stat {
  text-align: center;
}

.stat-number {
  font-family: var(--font-display);
  font-size: 3rem;
  font-weight: 800;
  color: var(--accent-primary);
  line-height: 1;
}

.stat-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-top: 0.5rem;
}

.parts-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin: 3rem 0;
}

.part-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 2rem;
  position: relative;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.part-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.part-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3), 0 0 20px rgba(0, 212, 170, 0.1);
}

.part-card:hover::before {
  transform: scaleX(1);
}

.part-card > a:last-child {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 1rem;
  color: var(--accent-primary);
  font-weight: 700;
  transition: all 0.2s;
}

.part-card > a:last-child:hover {
  gap: 1rem;
  text-decoration: none;
}

.part-card > a:last-child::after {
  content: '→';
  transition: transform 0.2s;
}

.part-card:hover > a:last-child::after {
  transform: translateX(4px);
}

.part-number {
  font-family: var(--font-display);
  font-size: 3rem;
  font-weight: 800;
  color: var(--accent-primary);
  line-height: 1;
  margin-bottom: 1rem;
}

.part-card h3 {
  margin-bottom: 1rem;
}

.part-card p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

.part-card ul {
  list-style: none;
  padding: 0;
  margin-bottom: 1.5rem;
}

.part-card li {
  padding: 0.25rem 0;
  padding-left: 1.5rem;
  position: relative;
  color: var(--text-secondary);
}

.part-card li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--accent-primary);
}

.cta-section {
  text-align: center;
  padding: 3rem 0;
}

.btn-large {
  padding: 1.25rem 2.5rem;
  font-size: 1.1rem;
  letter-spacing: 0.1em;
}

/* Homepage Additional Styles */
.why-learn-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin: 3rem 0;
}

.why-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 2rem;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.why-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.2);
}

.why-card h4 {
  color: var(--accent-primary);
  font-size: 1rem;
  margin-bottom: 1rem;
}

.why-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  margin: 0;
}

.design-principles {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
  margin: 3rem 0;
}

.principle {
  display: flex;
  gap: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 2rem;
  transition: all 0.3s;
}

.principle:hover {
  border-color: var(--accent-primary);
}

.principle-icon {
  font-size: 2rem;
  flex-shrink: 0;
}

.principle h4 {
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  font-size: 1rem;
}

.principle p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
  margin: 0;
}

/* Chapter Overview on Homepage */
.chapter-overview {
  background: linear-gradient(135deg, var(--bg-card) 0%, rgba(0, 212, 170, 0.03) 100%);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 2.5rem;
  margin: 3rem 0;
}

.chapter-overview h3 {
  color: var(--accent-primary);
  margin-bottom: 1.5rem;
  font-size: 1.2rem;
  text-align: center;
}

.chapter-overview ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
}

.chapter-overview li {
  padding: 0.5rem 0;
  padding-left: 1.5rem;
  position: relative;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.chapter-overview li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--accent-primary);
}

.chapter-overview a {
  color: var(--text-primary);
  font-weight: 600;
}

.chapter-overview a:hover {
  color: var(--accent-primary);
}

/* Responsive adjustments */
@media (max-width: 900px) {
  .why-learn-grid {
    grid-template-columns: 1fr;
  }

  .design-principles {
    grid-template-columns: 1fr;
  }

  .chapter-overview ul {
    grid-template-columns: 1fr;
  }
}

/* Buttons - Improved hover and click effects */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  background: var(--accent-primary);
  color: var(--bg-primary);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border: 2px solid var(--accent-primary);
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left 0.5s;
}

.btn:hover::before {
  left: 100%;
}

.btn:hover {
  background: transparent;
  color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 212, 170, 0.3);
  text-decoration: none;
}

.btn:active {
  transform: translateY(0);
  box-shadow: 0 2px 6px rgba(0, 212, 170, 0.2);
}

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

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

.btn-secondary {
  background: transparent;
  color: var(--accent-primary);
  border-color: var(--accent-primary);
}

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

.btn-large {
  padding: 1rem 2rem;
  font-size: 1rem;
}