:root {
  --bg-color: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --accent-color: #58a6ff;
  --accent-hover: #79c0ff;
  --border-color: #30363d;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, Courier, monospace;
  --max-width: 1000px;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  color: #ffffff;
  font-weight: 600;
  line-height: 1.25;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

h1 { font-size: 3rem; margin-bottom: 1.5rem; }
h2 { font-size: 2rem; margin-top: 3rem; border-bottom: 1px solid var(--border-color); padding-bottom: 0.5rem; }
h3 { font-size: 1.5rem; margin-top: 2rem; }

p {
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
}

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

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

strong {
  color: #ffffff;
  font-weight: 600;
}

code {
  font-family: var(--font-mono);
  background-color: rgba(110, 118, 129, 0.4);
  padding: 0.2em 0.4em;
  border-radius: 6px;
  font-size: 85%;
}

pre {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
}

pre code {
  background-color: transparent;
  padding: 0;
}

ul, ol {
  margin-bottom: 1.5rem;
  padding-left: 2rem;
}

li {
  margin-bottom: 0.5rem;
}

/* Layout */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
  width: 100%;
}

/* Navigation */
header {
  border-bottom: 1px solid var(--border-color);
  background-color: rgba(13, 17, 23, 0.95);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 4rem;
}

.logo {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: bold;
  color: #ffffff;
  text-decoration: none;
  letter-spacing: 0.05em;
}

.logo:hover {
  text-decoration: none;
  color: var(--text-primary);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
}

.nav-links a:hover,
.nav-links a.active {
  color: #ffffff;
  text-decoration: none;
}

/* Hamburger menu (mobile) */
.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-menu-btn svg {
  fill: currentColor;
}

/* Main Content */
main {
  flex: 1;
  padding: 4rem 0;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 4rem 0 6rem;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 4rem;
}

.hero h1 {
  font-size: 3.5rem;
  line-height: 1.1;
  margin-bottom: 1.5rem;
  background: linear-gradient(to right, #ffffff, var(--text-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p.subtitle {
  font-size: 1.5rem;
  color: var(--text-secondary);
  max-width: 800px;
  margin: 0 auto 2.5rem;
}

.button-group {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

.button {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 500;
  text-align: center;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.2s ease;
}

.button-primary {
  background-color: #238636;
  color: white;
  border-color: rgba(240, 246, 252, 0.1);
}

.button-primary:hover {
  background-color: #2ea043;
  color: white;
  text-decoration: none;
}

.button-outline {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.button-outline:hover {
  background-color: var(--bg-tertiary);
  border-color: #8b949e;
  color: #ffffff;
  text-decoration: none;
}

/* Sections */
.section-block {
  margin-bottom: 4rem;
}

/* Grid layout for features/architecture */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.card:hover {
  border-color: #8b949e;
  transform: translateY(-2px);
}

.card h3 {
  margin-top: 0;
  margin-bottom: 1rem;
  font-size: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.card h3::before {
  content: '';
  display: inline-block;
  width: 12px;
  height: 12px;
  background-color: var(--accent-color);
  border-radius: 50%;
}

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

/* Invariant Block */
.invariant-block {
  background-color: rgba(35, 134, 54, 0.1);
  border: 1px solid rgba(46, 160, 67, 0.4);
  border-radius: 8px;
  padding: 2rem;
  margin: 2rem 0;
  text-align: center;
}

.invariant-block code {
  font-size: 1.2rem;
  background: transparent;
  color: #3fb950;
  display: block;
}

/* Comparison Table */
.comparison-container {
  overflow-x: auto;
  margin-top: 2rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

th, td {
  padding: 1rem;
  border-bottom: 1px solid var(--border-color);
}

th {
  background-color: var(--bg-secondary);
  font-weight: 600;
  color: #ffffff;
}

tr:nth-child(even) {
  background-color: rgba(22, 27, 34, 0.5);
}

tr:hover {
  background-color: var(--bg-tertiary);
}

/* Architecture specific */
.layer-diagram {
  display: flex;
  flex-direction: column-reverse;
  gap: 1rem;
  margin: 3rem 0;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.layer {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1.5rem;
  text-align: center;
  position: relative;
  transition: all 0.3s ease;
}

.layer:hover {
  border-color: var(--accent-color);
  background-color: var(--bg-tertiary);
  transform: scale(1.02);
  z-index: 10;
}

.layer::after {
  content: '↓';
  position: absolute;
  top: -1.2rem;
  left: 50%;
  transform: translateX(-50%);
  color: var(--text-secondary);
  font-size: 1.2rem;
}

.layer:last-child::after {
  display: none;
}

.layer h3 {
  margin: 0 0 0.5rem 0;
  color: #ffffff;
}

.layer p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* Footer */
footer {
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  margin-top: auto;
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.5rem;
  }
  
  .hero p.subtitle {
    font-size: 1.2rem;
  }
  
  .nav-links {
    display: none;
    position: absolute;
    top: 4rem;
    left: 0;
    right: 0;
    background-color: var(--bg-color);
    flex-direction: column;
    padding: 1rem 2rem;
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
  }
  
  .nav-links.show {
    display: flex;
  }
  
  .mobile-menu-btn {
    display: block;
  }
  
  .footer-content {
    flex-direction: column;
    gap: 1rem;
  }
}