:root {
  /* Background */
  --bg-primary: #0a0a0a;
  --bg-surface: #141414;
  --bg-elevated: #1a1a1a;
  --border: #262626;
  --border-focus: #333333;

  /* Text */
  --text-primary: #fafafa;
  --text-body: #d4d4d8;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;

  /* Accent (Phosphor Green) */
  --accent: #4ade80;
  --accent-bright: #86efac;
  --accent-dim: #166534;
  --accent-glow: rgba(74, 222, 128, 0.1);

  /* Terminal */
  --term-bg: #0d0d0d;
  --term-border: #2a2a2a;
  --term-prompt: #4ade80;
  --term-cursor: #4ade80;
  --term-output: #d4d4d8;
  --term-comment: #6b7280;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  font-weight: 400;
  line-height: 1.7;
  color: var(--text-body);
  background-color: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: var(--bg-primary);
  font-weight: 600;
  border-radius: 4px;
  z-index: 100;
  text-decoration: none;
}

.skip-link:focus {
  top: 1rem;
}

/* Layout */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

@media (min-width: 768px) {
  .container {
    padding: 0 2rem;
  }
}

@media (min-width: 1100px) {
  .container {
    padding: 0;
  }
}

section {
  padding: 5rem 0;
}

/* Typography */
h1, h2, h3, h4 {
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  line-height: 1.3;
}

h1 {
  font-size: 3.5rem;
  font-weight: 700;
}

h2 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 2.5rem;
  text-align: center;
}

h3 {
  font-size: 1.1rem;
  font-weight: 600;
}

p {
  max-width: 65ch;
  margin-left: auto;
  margin-right: auto;
}

a {
  color: var(--text-body);
  text-decoration: none;
  transition: color 200ms ease;
}

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

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

/* Hero */
.hero {
  padding: 6rem 0 4rem;
  text-align: center;
}

.hero-wordmark {
  font-family: 'JetBrains Mono', monospace;
  font-size: 4rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 1.5rem;
  letter-spacing: -0.03em;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 2.5rem;
  margin-left: auto;
  margin-right: auto;
}

.hero-subtitle span {
  color: var(--text-body);
}

.install-block {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--term-bg);
  border: 1px solid var(--term-border);
  border-radius: 6px;
  padding: 0.75rem 1.25rem;
  margin-bottom: 3rem;
  position: relative;
}

.install-block code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.95rem;
  color: var(--text-primary);
}

.install-block .prompt {
  color: var(--term-prompt);
}

.copy-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  color: var(--text-muted);
  transition: color 200ms ease;
  display: flex;
  align-items: center;
}

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

.copy-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

.copy-btn.copied {
  color: var(--accent);
}

.hero-links {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-top: 2rem;
}

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

/* Terminal window */
.terminal {
  background: var(--term-bg);
  border: 1px solid var(--term-border);
  border-radius: 6px;
  padding: 1.5rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
  line-height: 1.5;
  overflow-x: auto;
  text-align: left;
  box-shadow: 0 0 60px var(--accent-glow);
  transition: border-color 200ms ease;
  position: relative;
}

.terminal:hover {
  border-color: var(--border-focus);
}

.terminal-title {
  position: absolute;
  top: 0;
  left: 0;
  padding: 0.4rem 1rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  border-bottom: 1px solid var(--term-border);
  border-right: 1px solid var(--term-border);
  border-radius: 6px 0 6px 0;
}

.terminal .prompt {
  color: var(--term-prompt);
  user-select: none;
}

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

.terminal .output {
  color: var(--term-output);
  white-space: pre;
}

.terminal .comment {
  color: var(--term-comment);
}

.terminal .cursor {
  display: inline-block;
  width: 0.55em;
  height: 1.1em;
  background: var(--term-cursor);
  vertical-align: text-bottom;
  animation: blink 1s step-end infinite;
}

@keyframes blink {
  50% { opacity: 0; }
}

.hero .terminal {
  max-width: 700px;
  margin: 0 auto;
  min-height: 260px;
}

/* How it works */
.steps-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.step-full {
  grid-column: 1 / -1;
}

.step-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  color: var(--accent);
  margin-bottom: 0.75rem;
  font-weight: 600;
}

/* Why Brain cards */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.card {
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1.5rem;
  transition: border-color 200ms ease;
}

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

.card h3 {
  color: var(--accent);
  font-family: 'JetBrains Mono', monospace;
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.card p {
  font-size: 0.93rem;
  color: var(--text-body);
  line-height: 1.6;
  margin-left: 0;
  margin-right: 0;
}

.section-punch {
  text-align: center;
  color: var(--text-secondary);
  font-size: 1rem;
  margin-left: auto;
  margin-right: auto;
}

.section-punch strong {
  color: var(--text-primary);
}

.section-punch code {
  font-family: 'JetBrains Mono', monospace;
  color: var(--accent);
  font-size: 0.9rem;
}

/* Agent integration */
.agent-section .terminal {
  max-width: 560px;
  margin: 0 auto 2rem;
}

.agent-tools {
  text-align: center;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  margin-left: auto;
  margin-right: auto;
}

.agent-desc {
  text-align: center;
  color: var(--text-body);
  margin-bottom: 1.5rem;
  max-width: 50ch;
  margin-left: auto;
  margin-right: auto;
}

.agent-clients {
  text-align: center;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-left: auto;
  margin-right: auto;
}

/* Quick start */
.quick-start .terminal {
  max-width: 700px;
  margin: 0 auto;
}

.quick-start .prereqs {
  margin-top: 1rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
}

/* Architecture */
.arch-diagram {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.arch-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.arch-arrow-down {
  width: 2px;
  height: 24px;
  background: var(--border);
  position: relative;
}

.arch-arrow-down::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  border-top: 6px solid var(--border);
}

.arch-box {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem 1.25rem;
  text-align: center;
  background: var(--bg-secondary, #141414);
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.arch-box--accent {
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 600;
}

.arch-box .arch-sub {
  font-size: 0.7rem;
  color: var(--text-muted);
}

.arch-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  width: 100%;
  margin-top: 0.5rem;
}

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

.arch-notes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  max-width: 700px;
  margin: 0 auto;
}

.arch-note {
  font-size: 0.85rem;
  text-align: center;
}

.arch-note strong {
  color: var(--text-primary);
  font-family: 'JetBrains Mono', monospace;
  font-weight: 600;
  display: block;
  margin-bottom: 0.25rem;
  font-size: 0.8rem;
}

/* Footer */
.site-footer {
  padding: 3rem 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.footer-links {
  margin-top: 0.5rem;
}

.footer-links a {
  color: var(--text-muted);
  margin: 0 0.5rem;
}

/* Scroll reveal */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 400ms ease-out, transform 400ms ease-out;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .terminal .cursor {
    animation: none;
    opacity: 1;
  }
}

/* Responsive */
@media (max-width: 768px) {
  h1, .hero-wordmark {
    font-size: 2.5rem;
  }

  h2 {
    font-size: 1.4rem;
  }

  section {
    padding: 3.5rem 0;
  }

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

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

  .arch-notes {
    grid-template-columns: 1fr;
  }

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

  .arch-diagram {
    padding: 0 1rem;
  }

  .terminal {
    font-size: 0.78rem;
  }

  .container {
    padding: 0 1.25rem;
  }
}

@media (min-width: 769px) and (max-width: 1024px) {
  .cards-grid {
    grid-template-columns: 1fr 1fr;
  }
}