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

:root {
  --color-accent: #5856D6;
  --color-accent-hover: #4745B5;
  --color-accent-light: rgba(88, 86, 214, 0.08);
  --color-accent-glow: rgba(88, 86, 214, 0.15);

  --color-text-primary: #1a1a2e;
  --color-text-secondary: #64648c;
  --color-text-tertiary: #8e8eaa;

  --color-bg: #ffffff;
  --color-bg-secondary: #f8f8fc;
  --color-bg-tertiary: #f0f0f8;
  --color-border: rgba(0, 0, 0, 0.06);
  --color-border-strong: rgba(0, 0, 0, 0.1);

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-pill: 999px;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.08);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.1);

  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text-primary);
  background: var(--color-bg);
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
  display: block;
}

/* ===== Layout ===== */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}

.section-header {
  text-align: center;
  max-width: 560px;
  margin: 0 auto 64px;
}

.section-header h2 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.section-header p {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
}

/* ===== Navigation ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--color-border);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 1.125rem;
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--color-text-primary);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--color-text-primary);
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9375rem;
  font-weight: 500;
  padding: 10px 20px;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-sm {
  padding: 6px 14px;
  font-size: 0.8125rem;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-pill);
}

.btn-sm:hover {
  background: var(--color-bg-tertiary);
  border-color: var(--color-border-strong);
}

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

.btn-primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  box-shadow: 0 4px 16px rgba(88, 86, 214, 0.3);
}

.btn-secondary {
  background: var(--color-bg);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border-strong);
}

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

/* ===== Hero ===== */
.hero {
  padding: 160px 0 100px;
  overflow: hidden;
}

/* ponytail: the hub hero is centered and copy-only — the project sites put a
   device/terminal mockup in a second column, which the hub has nothing to fill. */
.hero .container {
  text-align: center;
}

.hero-badge {
  display: inline-block;
  padding: 6px 14px;
  background: var(--color-accent-light);
  color: var(--color-accent);
  font-size: 0.8125rem;
  font-weight: 600;
  border-radius: var(--radius-pill);
  margin-bottom: 24px;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 20px;
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  max-width: 620px;
  margin: 0 auto 32px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

/* ===== Features ===== */
.features {
  padding: 100px 0;
  background: var(--color-bg-secondary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: all var(--transition-base);
}

.feature-card:hover {
  border-color: var(--color-accent-glow);
  box-shadow: var(--shadow-md), 0 0 0 1px var(--color-accent-glow);
  transform: translateY(-2px);
}

.feature-icon {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-accent-light);
  color: var(--color-accent);
  border-radius: var(--radius-sm);
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.feature-card p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.pill {
  padding: 6px 14px;
  background: var(--color-bg-tertiary);
  color: var(--color-text-secondary);
  font-size: 0.8125rem;
  font-weight: 500;
  font-family: var(--font-mono);
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-border);
}

/* ===== Projects ===== */
.projects {
  padding: 100px 0;
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.project-card {
  display: flex;
  flex-direction: column;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: all var(--transition-base);
}

.project-card:hover {
  border-color: var(--color-accent-glow);
  box-shadow: var(--shadow-md), 0 0 0 1px var(--color-accent-glow);
  transform: translateY(-2px);
}

.project-logo {
  margin-bottom: 20px;
}

.project-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: 8px;
}

.project-card p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
}

.project-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

.project-links {
  display: flex;
  gap: 16px;
  margin-top: auto;
  font-size: 0.875rem;
  font-weight: 500;
}

.project-links a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--color-accent);
  transition: opacity var(--transition-fast);
}

.project-links a:hover {
  opacity: 0.7;
}

.project-links .link-muted {
  color: var(--color-text-tertiary);
}

/* ===== Stack diagram ===== */
.stack {
  padding: 100px 0;
  background: var(--color-bg-secondary);
}

.stack-diagram {
  max-width: 640px;
  margin: 0 auto;
}

.stack-flow {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.stack-node {
  width: 100%;
  max-width: 420px;
  text-align: center;
  padding: 18px 24px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.stack-node strong {
  display: block;
  font-size: 0.9375rem;
  font-weight: 600;
}

.stack-node span {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

.stack-node-accent {
  border-color: var(--color-accent-glow);
  box-shadow: var(--shadow-md), 0 0 0 1px var(--color-accent-glow);
}

.stack-arrow {
  color: var(--color-text-tertiary);
  font-size: 1.125rem;
  line-height: 1;
}

.stack-divider {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 40px 0 32px;
  color: var(--color-text-tertiary);
  font-size: 0.8125rem;
  font-weight: 500;
}

.stack-divider::before,
.stack-divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--color-border-strong);
}

.stack-aside {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.stack-aside .stack-node {
  max-width: 260px;
}

/* ===== Language switcher ===== */
.lang-switch {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 3px;
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-pill);
}

.lang-switch button {
  padding: 4px 12px;
  font-family: inherit;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  background: none;
  border: none;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.lang-switch button:hover {
  color: var(--color-text-primary);
}

.lang-switch button[aria-current='true'] {
  background: var(--color-bg);
  color: var(--color-text-primary);
  box-shadow: var(--shadow-sm);
}

/* ===== Footer ===== */
.footer {
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

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

.footer-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  font-size: 0.8125rem;
  color: var(--color-text-tertiary);
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--color-text-primary);
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

@media (max-width: 640px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 24px;
    gap: 16px;
    border-bottom: 1px solid var(--color-border);
  }

  .nav-links.open {
    display: flex;
  }

  .lang-switch {
    align-self: center;
  }

  .nav-toggle {
    display: block;
  }

  .hero {
    padding: 120px 0 60px;
  }

  .hero h1 {
    font-size: 2.5rem;
  }

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

  .section-header h2 {
    font-size: 1.75rem;
  }

  .stack-aside {
    flex-direction: column;
  }

  .stack-aside .stack-node {
    max-width: 100%;
  }

  .footer-inner {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }
}