/* Cloudflare-class brand tokens — light mode only.
 * Inspired by developers.cloudflare.com but our own. CF orange as a single
 * structural accent, lots of white space, soft borders. Inter where possible,
 * system stack as a fallback so we work without web-font loading on first paint.
 */

:root {
  --cf-orange: #F6821F;
  --cf-orange-soft: #FAAE40;
  --cf-orange-deep: #C4691A;

  --ink: #1F1F1F;
  --text: #2F2F2F;
  --text-2: #4F4F4F;
  --muted: #767676;

  --bg: #FAFAF8;
  --surface: #FFFFFF;
  --surface-2: #F4F4F1;
  --border: #E6E5DF;
  --border-2: #D6D5CC;

  --good: #2C7A39;
  --warn: #B7510B;
  --bad: #B33A3A;

  --font-sans: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", Roboto, system-ui, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Menlo", "Cascadia Mono", monospace;

  --t-xs: 12px;
  --t-sm: 14px;
  --t-base: 16px;
  --t-lg: 18px;
  --t-xl: 22px;
  --t-2xl: 28px;
  --t-3xl: 36px;
  --t-4xl: 52px;

  --r-sm: 6px;
  --r-md: 10px;
  --r-lg: 14px;

  --sh-sm: 0 1px 2px rgba(20,20,20,0.04);
  --sh-md: 0 4px 14px rgba(20,20,20,0.06);
  --sh-lg: 0 14px 36px rgba(20,20,20,0.10);

  --max-w: 1080px;
  --max-w-prose: 720px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: var(--t-lg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body { min-height: 100vh; display: flex; flex-direction: column; }

a {
  color: var(--cf-orange-deep);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 120ms ease;
}
a:hover { border-bottom-color: currentColor; }

h1, h2, h3, h4 {
  color: var(--ink);
  font-weight: 700;
  line-height: 1.18;
  letter-spacing: -0.01em;
  margin: 0 0 12px 0;
}
h1 { font-size: var(--t-4xl); letter-spacing: -0.02em; }
h2 { font-size: var(--t-2xl); margin-top: 48px; }
h3 { font-size: var(--t-xl); margin-top: 32px; }

p { margin: 0 0 14px 0; max-width: var(--max-w-prose); }

code, pre {
  font-family: var(--font-mono);
  font-size: 13.5px;
}
code:not(pre code) {
  background: var(--surface-2);
  border: 1px solid var(--border);
  padding: 1px 6px;
  border-radius: var(--r-sm);
  font-size: 13px;
}
pre {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  padding: 16px 18px;
  overflow-x: auto;
  margin: 18px 0;
  box-shadow: var(--sh-sm);
}

/* ===== Site chrome ============================================ */

.shell {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.nav {
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: saturate(150%) blur(8px);
  background: rgba(255,255,255,0.92);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  color: var(--ink);
  font-size: 17px;
  border: 0;
}
.nav-brand .dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--cf-orange);
  display: inline-block;
}
.nav-right { display: flex; align-items: center; gap: 14px; font-size: var(--t-sm); color: var(--muted); }
.nav-right a { color: var(--muted); border: 0; }
.nav-right a:hover { color: var(--ink); }

footer.site {
  margin-top: 80px;
  border-top: 1px solid var(--border);
  padding: 28px 0 40px 0;
  color: var(--muted);
  font-size: var(--t-sm);
}
footer.site .shell {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

/* ===== Homepage hero ========================================== */

.hero {
  padding: 68px 0 32px 0;
}
.hero .eyebrow {
  display: inline-block;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 11.5px;
  font-weight: 700;
  color: var(--cf-orange-deep);
  margin-bottom: 18px;
  background: rgba(246,130,31,0.08);
  padding: 5px 10px;
  border-radius: 999px;
}
.hero h1 {
  margin: 0 0 12px 0;
  max-width: 760px;
}
.hero p.lede {
  font-size: var(--t-lg);
  color: var(--text-2);
  max-width: 640px;
  margin-bottom: 0;
}

/* ===== Card grid ============================================== */

.section-label {
  text-transform: uppercase;
  font-size: 11.5px;
  letter-spacing: 0.12em;
  color: var(--muted);
  font-weight: 700;
  margin: 56px 0 16px 0;
}

.card-grid {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 22px 22px 24px 22px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
  position: relative;
  overflow: hidden;
  color: var(--ink);
  border-bottom: 1px solid var(--border);
}
.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--sh-md);
  border-color: var(--border-2);
}
.card.disabled {
  opacity: 0.55;
  pointer-events: none;
}
.card .card-eyebrow {
  text-transform: uppercase;
  font-size: 10.5px;
  letter-spacing: 0.14em;
  color: var(--cf-orange-deep);
  font-weight: 700;
}
.card.disabled .card-eyebrow { color: var(--muted); }
.card h3 {
  margin: 0;
  font-size: var(--t-xl);
  letter-spacing: -0.01em;
}
.card p {
  margin: 0;
  color: var(--text-2);
  font-size: var(--t-sm);
  line-height: 1.5;
}
.card .card-arrow {
  position: absolute;
  right: 18px;
  top: 22px;
  font-size: 18px;
  color: var(--muted);
  transition: transform 160ms ease, color 160ms ease;
}
.card:hover .card-arrow {
  transform: translateX(3px);
  color: var(--cf-orange);
}

/* ===== Lesson page ============================================ */

article.lesson {
  padding: 56px 0 40px 0;
}
article.lesson .breadcrumb {
  font-size: var(--t-sm);
  color: var(--muted);
  margin-bottom: 18px;
}
article.lesson .breadcrumb a { color: var(--muted); border: 0; }
article.lesson .breadcrumb a:hover { color: var(--ink); }

article.lesson > h1 { margin-bottom: 16px; }
article.lesson > .lede {
  font-size: var(--t-lg);
  color: var(--text-2);
  max-width: var(--max-w-prose);
  margin-bottom: 8px;
}

article.lesson .prose {
  max-width: var(--max-w-prose);
}

article.lesson .prose ul, article.lesson .prose ol { padding-left: 22px; margin: 12px 0; }
article.lesson .prose li { margin-bottom: 6px; }

article.lesson .callout {
  background: rgba(246,130,31,0.06);
  border: 1px solid rgba(246,130,31,0.20);
  border-left: 3px solid var(--cf-orange);
  border-radius: var(--r-md);
  padding: 14px 18px;
  margin: 18px 0;
  max-width: var(--max-w-prose);
}
article.lesson .callout strong { color: var(--cf-orange-deep); }

/* ===== KV demo widget ========================================= */

.kv-demo {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 24px;
  margin: 28px 0;
  box-shadow: var(--sh-sm);
}
.kv-demo .kv-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 18px;
}
.kv-demo .kv-header h4 {
  margin: 0;
  font-size: var(--t-lg);
}
.kv-demo .kv-header .kv-status {
  font-size: 12.5px;
  color: var(--muted);
  font-family: var(--font-mono);
  background: var(--surface-2);
  border: 1px solid var(--border);
  padding: 4px 10px;
  border-radius: var(--r-sm);
  white-space: nowrap;
}
.kv-demo .kv-status.ok { border-color: rgba(44,122,57,0.3); color: var(--good); }
.kv-demo .kv-status.fast { border-color: rgba(246,130,31,0.3); color: var(--cf-orange-deep); }
.kv-demo .kv-status.cold { border-color: rgba(183,81,11,0.3); color: var(--warn); }

.mailbox-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  gap: 10px;
  margin-bottom: 14px;
}
.mailbox {
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  padding: 14px 12px;
  cursor: pointer;
  background: var(--surface-2);
  transition: border-color 120ms ease, transform 120ms ease, background 120ms ease;
  text-align: left;
  font-family: var(--font-mono);
}
.mailbox:hover {
  border-color: var(--cf-orange);
  transform: translateY(-1px);
}
.mailbox.selected {
  border-color: var(--cf-orange);
  background: rgba(246,130,31,0.06);
}
.mailbox .mb-num {
  font-size: 11px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-family: var(--font-sans);
}
.mailbox .mb-title {
  font-size: 14px;
  color: var(--ink);
  font-weight: 600;
  margin-top: 4px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.mailbox .mb-empty {
  color: var(--muted);
  font-style: italic;
  font-weight: 400;
}
.mailbox .mb-when {
  font-size: 11px;
  color: var(--muted);
  margin-top: 6px;
}

.kv-edit {
  border-top: 1px solid var(--border);
  padding-top: 16px;
  margin-top: 4px;
}
.kv-edit label {
  display: block;
  font-size: var(--t-sm);
  color: var(--text-2);
  margin: 8px 0 4px 0;
  font-weight: 600;
}
.kv-edit input, .kv-edit textarea {
  width: 100%;
  font: inherit;
  font-size: var(--t-sm);
  padding: 9px 11px;
  border: 1px solid var(--border-2);
  border-radius: var(--r-sm);
  background: var(--surface);
  color: var(--ink);
  font-family: var(--font-mono);
}
.kv-edit input:focus, .kv-edit textarea:focus {
  outline: none;
  border-color: var(--cf-orange);
  box-shadow: 0 0 0 3px rgba(246,130,31,0.15);
}
.kv-edit textarea { min-height: 80px; resize: vertical; }
.kv-edit .key-display {
  font-family: var(--font-mono);
  font-size: 13px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  padding: 6px 10px;
  border-radius: var(--r-sm);
  color: var(--cf-orange-deep);
  display: inline-block;
}

.kv-actions {
  display: flex;
  gap: 8px;
  margin-top: 14px;
  flex-wrap: wrap;
}

button.btn {
  font: inherit;
  font-size: var(--t-sm);
  font-weight: 600;
  padding: 9px 16px;
  border-radius: var(--r-sm);
  border: 1px solid var(--border-2);
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
  transition: background 120ms ease, border-color 120ms ease, transform 80ms ease;
}
button.btn:hover { border-color: var(--ink); }
button.btn:active { transform: translateY(1px); }
button.btn:disabled { opacity: 0.5; cursor: default; }

button.btn.primary {
  background: var(--cf-orange);
  border-color: var(--cf-orange);
  color: white;
}
button.btn.primary:hover { background: var(--cf-orange-deep); border-color: var(--cf-orange-deep); }

button.btn.ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text-2);
}
button.btn.ghost:hover { color: var(--ink); border-color: var(--border-2); }

.kv-log {
  margin-top: 16px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--text-2);
  max-height: 160px;
  overflow-y: auto;
}
.kv-log .log-entry { line-height: 1.6; }
.kv-log .log-entry .t { color: var(--muted); }
.kv-log .log-entry.write { color: var(--cf-orange-deep); }
.kv-log .log-entry.read { color: var(--good); }
.kv-log .log-entry.error { color: var(--bad); }

/* ===== Race demo ============================================== */
.race-prompt {
  background: var(--surface-2);
  border: 1px dashed var(--border-2);
  border-radius: var(--r-md);
  padding: 14px 16px;
  margin: 18px 0;
  font-size: var(--t-sm);
  color: var(--text-2);
  max-width: var(--max-w-prose);
}
.race-prompt strong { color: var(--ink); }

/* ===== Code blocks (manual ones) ============================== */
.codeblock {
  margin: 16px 0;
  max-width: var(--max-w-prose);
}

@media (max-width: 640px) {
  h1 { font-size: 36px; }
  .mailbox-grid { grid-template-columns: repeat(auto-fill, minmax(100px, 1fr)); }
  .hero { padding: 48px 0 24px 0; }
}