:root {
  --bg: #fcfdfc;
  --surface: #ffffff;
  --surface-subtle: #f4f6f4;
  --border: #e3e7e4;
  --border-subtle: #edf0ed;
  --text: #131916;
  --text-muted: #4e5a53;
  --text-dim: #76837c;
  --brand: #2e5e4e;
  --brand-hover: #244b3e;
  --brand-light: #eaf1ed;
  --brand-light-text: #21473a;
  --code-bg: #f1f4f2;
  --radius: 8px;
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Inter, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

[data-theme="dark"] {
  --bg: #0f1412;
  --surface: #151b18;
  --surface-subtle: #1b2320;
  --border: #232d28;
  --border-subtle: #1c2420;
  --text: #e7ece9;
  --text-muted: #95a39b;
  --text-dim: #64736b;
  --brand: #3e7e69;
  --brand-hover: #4c967d;
  --brand-light: #162620;
  --brand-light-text: #7bc4ad;
  --code-bg: #19211d;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1412;
    --surface: #151b18;
    --surface-subtle: #1b2320;
    --border: #232d28;
    --border-subtle: #1c2420;
    --text: #e7ece9;
    --text-muted: #95a39b;
    --text-dim: #64736b;
    --brand: #3e7e69;
    --brand-hover: #4c967d;
    --brand-light: #162620;
    --brand-light-text: #7bc4ad;
    --code-bg: #19211d;
  }
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.container {
  max-width: 680px;
  margin: 0 auto;
  padding: 2.5rem 1.25rem 4.5rem;
}

/* Top bar */
.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 3.5rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.brand-mark {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  display: block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  font-size: 0.9rem;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
}

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

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  width: 32px;
  height: 32px;
  border-radius: 6px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover {
  color: var(--text);
  border-color: var(--text-dim);
}

/* Hero */
.hero {
  margin-bottom: 3rem;
}

h1 {
  font-size: 2.25rem;
  font-weight: 750;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.hero-lead {
  font-size: 1.125rem;
  color: var(--text-muted);
  line-height: 1.55;
  margin-bottom: 1.75rem;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.95rem;
  font-weight: 600;
  padding: 0.65rem 1.25rem;
  border-radius: 6px;
  text-decoration: none;
  cursor: pointer;
}

.btn-primary {
  background-color: var(--brand);
  color: #ffffff;
  border: 1px solid transparent;
}

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

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

.btn-secondary:hover {
  background-color: var(--surface-subtle);
}

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

/* Storage sieve demonstration */
.inspector {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 2.5rem 0 3.5rem;
}

.inspector-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-subtle);
  margin-bottom: 1rem;
}

.inspector-title {
  font-size: 0.9rem;
  font-weight: 650;
  color: var(--text);
}

.inspector-sub {
  font-size: 0.8rem;
  color: var(--brand-light-text);
  background: var(--brand-light);
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  font-weight: 500;
}

.inspector-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.inspector-item {
  background: var(--surface-subtle);
  padding: 0.75rem 1rem;
  border-radius: 6px;
  border: 1px solid var(--border-subtle);
}

.inspector-item-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
}

.inspector-item-val {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
}

.inspector-footer {
  margin-top: 1rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.85rem;
  color: var(--text-muted);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* Sections */
section {
  margin-top: 3.5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

h2 {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

p {
  margin-bottom: 1rem;
  color: var(--text-muted);
}

p:last-child {
  margin-bottom: 0;
}

/* Feature definition list */
.feature-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.feature-row {
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 1.25rem;
  align-items: baseline;
}

.feature-term {
  font-weight: 650;
  font-size: 0.95rem;
  color: var(--text);
}

.feature-desc {
  font-size: 0.925rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Ordered steps */
.steps {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  padding-left: 0;
  list-style: none;
}

.step-item {
  display: grid;
  grid-template-columns: 24px 1fr;
  gap: 1rem;
}

.step-num {
  font-weight: 700;
  color: var(--brand);
  font-size: 0.95rem;
  line-height: 1.5;
}

.step-body h3 {
  font-size: 1rem;
  font-weight: 650;
  margin-bottom: 0.35rem;
  color: var(--text);
}

.step-body p {
  font-size: 0.9rem;
  line-height: 1.55;
}

/* Code snippet */
.code-box {
  margin-top: 0.75rem;
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.5rem 0.75rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

code {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text);
}

.copy-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
}

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

/* Footer */
footer {
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-dim);
}

footer a {
  color: var(--text-muted);
  text-decoration: underline;
  text-underline-offset: 2px;
}

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

.footer-nav {
  display: flex;
  gap: 1.25rem;
}

@media (max-width: 600px) {
  .feature-row {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }
  .inspector-list {
    grid-template-columns: 1fr;
  }
  .inspector-footer {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.25rem;
  }
  .cta-row {
    flex-direction: column;
    align-items: stretch;
  }
  .btn {
    justify-content: center;
  }
  footer {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
}