:root {
  color-scheme: light;
  --bg: #f5f3ee;
  --surface: #fffdf8;
  --surface-2: #edeae2;
  --text: #17201f;
  --muted: #626b68;
  --border: #d5d2ca;
  --border-strong: #a9aca6;
  --accent: #c84d2f;
  --accent-dark: #92351f;
  --success: #216c4b;
  --danger: #a4342a;
  --radius: 8px;
  --shadow: 0 12px 34px rgba(23, 32, 31, .08);
  --max: 1120px;
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg: #151918;
  --surface: #1d2220;
  --surface-2: #272c2a;
  --text: #f2f0e9;
  --muted: #abb2ae;
  --border: #373e3b;
  --border-strong: #646c68;
  --accent: #ed7958;
  --accent-dark: #ff9b7e;
  --success: #72c99e;
  --danger: #ff938a;
  --shadow: 0 12px 34px rgba(0, 0, 0, .22);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

button, input, select, textarea { font: inherit; }

a { color: inherit; text-underline-offset: 3px; }

a:hover { color: var(--accent-dark); }

button, a, input, select, textarea { -webkit-tap-highlight-color: transparent; }

:focus-visible { outline: 3px solid color-mix(in srgb, var(--accent) 65%, transparent); outline-offset: 2px; }

.skip-link {
  position: fixed;
  left: 12px;
  top: -80px;
  z-index: 100;
  padding: 9px 14px;
  background: var(--text);
  color: var(--bg);
  border-radius: 4px;
}

.skip-link:focus { top: 12px; }

.container { width: min(calc(100% - 40px), var(--max)); margin-inline: auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(10px);
}

.header-inner { min-height: 68px; display: flex; align-items: center; justify-content: space-between; gap: 28px; }

.wordmark { display: inline-flex; align-items: baseline; gap: 8px; text-decoration: none; font-size: 1.08rem; font-weight: 760; letter-spacing: -.025em; }
.wordmark::before { content: "Bƒ"; color: var(--accent); font-family: ui-monospace, SFMono-Regular, Consolas, monospace; font-size: .86rem; font-weight: 800; letter-spacing: -.08em; }

.site-nav { display: flex; align-items: center; gap: 5px; }
.site-nav a, .theme-toggle { padding: 8px 11px; border: 1px solid transparent; border-radius: 5px; text-decoration: none; color: var(--muted); background: transparent; cursor: pointer; }
.site-nav a:hover, .site-nav a[aria-current="page"], .theme-toggle:hover { border-color: var(--border); background: var(--surface); color: var(--text); }
.theme-toggle { min-width: 40px; color: var(--text); }

main { min-height: calc(100vh - 240px); }

.hero { padding: clamp(64px, 10vw, 118px) 0 48px; border-bottom: 1px solid var(--border); }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(260px, .65fr); gap: clamp(36px, 7vw, 88px); align-items: end; }
.eyebrow { margin: 0 0 15px; color: var(--accent-dark); font: 700 .76rem/1.3 ui-monospace, SFMono-Regular, Consolas, monospace; letter-spacing: .09em; text-transform: uppercase; }
h1, h2, h3 { line-height: 1.15; letter-spacing: -.035em; }
h1 { max-width: 820px; margin: 0; font-size: clamp(2.45rem, 6.2vw, 5.4rem); font-weight: 760; }
.page-head h1, .tool-head h1 { font-size: clamp(2.15rem, 5vw, 4rem); }
h2 { margin: 0 0 16px; font-size: clamp(1.65rem, 3vw, 2.35rem); }
h3 { margin: 0 0 8px; font-size: 1.06rem; letter-spacing: -.015em; }
.hero-copy { max-width: 640px; margin: 22px 0 0; color: var(--muted); font-size: clamp(1rem, 2vw, 1.22rem); }

.system-note { border-top: 2px solid var(--text); padding-top: 15px; color: var(--muted); font-size: .92rem; }
.system-note strong { display: block; margin-bottom: 6px; color: var(--text); font: 700 .75rem/1.4 ui-monospace, SFMono-Regular, Consolas, monospace; text-transform: uppercase; letter-spacing: .07em; }

.search-panel { margin-top: 36px; max-width: 760px; }
.search-box { position: relative; }
.search-box label { display: block; margin-bottom: 8px; font-weight: 700; }
.search-box input { width: 100%; min-height: 58px; padding: 12px 124px 12px 48px; border: 1px solid var(--border-strong); border-radius: var(--radius); background: var(--surface); color: var(--text); box-shadow: var(--shadow); }
.search-box::before { content: "/"; position: absolute; left: 17px; bottom: 15px; color: var(--accent); font: 800 1.1rem ui-monospace, SFMono-Regular, Consolas, monospace; }
.search-hint { position: absolute; right: 15px; bottom: 17px; color: var(--muted); font: 600 .75rem ui-monospace, SFMono-Regular, Consolas, monospace; }

.section { padding: clamp(54px, 8vw, 88px) 0; }
.section + .section { border-top: 1px solid var(--border); }
.section-head { display: flex; justify-content: space-between; gap: 24px; align-items: end; margin-bottom: 30px; }
.section-head p { max-width: 580px; margin: 0; color: var(--muted); }
.text-link { font-weight: 700; color: var(--accent-dark); white-space: nowrap; }

.tool-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); border-top: 1px solid var(--border-strong); }
.tool-card { position: relative; min-width: 0; padding: 24px 44px 24px 0; border-bottom: 1px solid var(--border); text-decoration: none; }
.tool-card:nth-child(odd) { padding-right: 36px; border-right: 1px solid var(--border); }
.tool-card:nth-child(even) { padding-left: 36px; }
.tool-card::after { content: "→"; position: absolute; right: 8px; top: 24px; color: var(--accent); transition: transform .15s ease; }
.tool-card:nth-child(odd)::after { right: 36px; }
.tool-card:hover::after { transform: translateX(4px); }
.tool-card p { margin: 0; color: var(--muted); font-size: .93rem; }
.tool-card .tag, .tag { display: inline-block; margin-bottom: 9px; color: var(--accent-dark); font: 700 .7rem ui-monospace, SFMono-Regular, Consolas, monospace; text-transform: uppercase; letter-spacing: .07em; }
.tool-card[hidden] { display: none; }
.empty-state { display: none; margin: 24px 0 0; padding: 18px; border-left: 3px solid var(--accent); background: var(--surface); }
.empty-state.is-visible { display: block; }

.category-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.category-card { padding: 24px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.category-card .count { color: var(--accent); font: 700 .75rem ui-monospace, SFMono-Regular, Consolas, monospace; }
.category-card p { color: var(--muted); }
.category-card a { font-weight: 700; }

.proof-strip { display: grid; grid-template-columns: repeat(4, 1fr); border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.proof-strip div { padding: 20px; border-right: 1px solid var(--border); }
.proof-strip div:last-child { border-right: 0; }
.proof-strip strong { display: block; margin-bottom: 3px; font-size: .92rem; }
.proof-strip span { color: var(--muted); font-size: .82rem; }

.page-head, .tool-head { padding: clamp(48px, 8vw, 84px) 0 38px; border-bottom: 1px solid var(--border); }
.page-head p, .tool-head .lede { max-width: 720px; margin: 17px 0 0; color: var(--muted); font-size: 1.08rem; }
.breadcrumbs { margin-bottom: 20px; color: var(--muted); font-size: .83rem; }
.breadcrumbs ol { display: flex; flex-wrap: wrap; gap: 8px; margin: 0; padding: 0; list-style: none; }
.breadcrumbs li:not(:last-child)::after { content: "/"; margin-left: 8px; color: var(--border-strong); }

.filter-bar { display: flex; flex-wrap: wrap; gap: 8px; margin: 24px 0; }
.filter-btn { padding: 8px 13px; border: 1px solid var(--border); border-radius: 999px; background: var(--surface); color: var(--muted); cursor: pointer; }
.filter-btn[aria-pressed="true"] { border-color: var(--text); background: var(--text); color: var(--bg); }

.tool-layout { display: grid; grid-template-columns: minmax(0, 1.45fr) minmax(240px, .55fr); gap: clamp(30px, 6vw, 70px); align-items: start; }
.tool-app { border: 1px solid var(--border-strong); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); overflow: hidden; }
.tool-app-header { padding: 14px 20px; border-bottom: 1px solid var(--border); background: var(--surface-2); color: var(--muted); font: 700 .75rem ui-monospace, SFMono-Regular, Consolas, monospace; text-transform: uppercase; letter-spacing: .06em; }
.tool-form { padding: clamp(20px, 4vw, 34px); }
.form-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.field { min-width: 0; }
.field-full { grid-column: 1 / -1; }
.field-group { margin: 0; padding: 0; border: 0; }
.field label, .fieldset-label { display: block; margin-bottom: 7px; font-size: .86rem; font-weight: 720; }
.field input, .field select, .field textarea { width: 100%; min-height: 46px; border: 1px solid var(--border-strong); border-radius: 5px; background: var(--bg); color: var(--text); padding: 10px 12px; }
.field textarea { min-height: 220px; resize: vertical; font-family: ui-monospace, SFMono-Regular, Consolas, monospace; font-size: .88rem; line-height: 1.55; tab-size: 2; }
.field input:focus, .field select:focus, .field textarea:focus { border-color: var(--accent); }
.segmented { display: flex; flex-wrap: wrap; gap: 7px; }
.segmented label { position: relative; margin: 0; }
.segmented input { position: absolute; opacity: 0; pointer-events: none; }
.segmented span { display: block; padding: 8px 11px; border: 1px solid var(--border); border-radius: 5px; background: var(--bg); cursor: pointer; }
.segmented input:checked + span { border-color: var(--text); background: var(--text); color: var(--bg); }
.segmented input:focus-visible + span { outline: 3px solid color-mix(in srgb, var(--accent) 65%, transparent); outline-offset: 2px; }
.actions { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 20px; }
.button { min-height: 44px; padding: 9px 16px; border: 1px solid var(--text); border-radius: 5px; background: var(--text); color: var(--bg); font-weight: 720; cursor: pointer; }
.button:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff; }
.button-secondary { background: transparent; color: var(--text); border-color: var(--border-strong); }
.button-secondary:hover { background: var(--surface-2); border-color: var(--text); color: var(--text); }
.button-small { min-height: 36px; padding: 6px 10px; font-size: .82rem; }
.error { min-height: 1.5em; margin: 12px 0 0; color: var(--danger); font-size: .88rem; }
.result { margin-top: 22px; padding: 20px; border-left: 3px solid var(--accent); background: var(--surface-2); }
.result[hidden] { display: none; }
.result-label { margin: 0 0 5px; color: var(--muted); font: 700 .72rem ui-monospace, SFMono-Regular, Consolas, monospace; text-transform: uppercase; letter-spacing: .07em; }
.result-primary { margin: 0; font-size: clamp(1.45rem, 4vw, 2.1rem); font-weight: 760; letter-spacing: -.03em; overflow-wrap: anywhere; }
.result-details { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 15px; }
.result-details div { padding-top: 10px; border-top: 1px solid var(--border); }
.result-details span { display: block; color: var(--muted); font-size: .75rem; }
.result-details strong { font-size: .92rem; overflow-wrap: anywhere; }
.privacy-note { margin: 16px 0 0; color: var(--muted); font-size: .79rem; }
.output-area { min-height: 170px !important; }
.status-valid { color: var(--success); }
.status-invalid { color: var(--danger); }
.uuid-list { display: grid; gap: 8px; margin-top: 18px; }
.uuid-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 10px 12px; border: 1px solid var(--border); border-radius: 5px; background: var(--bg); }
.uuid-row code { overflow-wrap: anywhere; font-size: .83rem; }

.tool-aside { position: sticky; top: 92px; }
.aside-block { padding: 18px 0; border-top: 1px solid var(--border); }
.aside-block:first-child { border-top: 2px solid var(--text); }
.aside-block h2 { margin-bottom: 10px; font-size: 1rem; }
.aside-block p, .aside-block li { color: var(--muted); font-size: .88rem; }
.aside-block ul { margin: 0; padding-left: 18px; }
.aside-block a { color: var(--text); }
.content { max-width: 780px; }
.content h2 { margin-top: 42px; font-size: 1.55rem; }
.content h2:first-child { margin-top: 0; }
.content p, .content li { color: var(--muted); }
.content strong { color: var(--text); }
.formula { padding: 15px 18px; border: 1px solid var(--border); border-radius: 5px; background: var(--surface); font-family: ui-monospace, SFMono-Regular, Consolas, monospace; font-size: .88rem; overflow-x: auto; }

.legal-meta { color: var(--muted); font-size: .85rem; }
.notice { padding: 18px; border: 1px solid var(--border); border-left: 3px solid var(--accent); background: var(--surface); }
.error-code { margin: 0; color: var(--accent); font: 800 clamp(4rem, 18vw, 9rem)/1 ui-monospace, SFMono-Regular, Consolas, monospace; }

.site-footer { margin-top: 20px; border-top: 1px solid var(--border); }
.footer-inner { display: grid; grid-template-columns: 1fr auto; gap: 28px; align-items: start; padding: 38px 0; }
.footer-copy { margin: 9px 0 0; color: var(--muted); font-size: .83rem; }
.footer-nav { display: flex; flex-wrap: wrap; gap: 18px; font-size: .88rem; }

@media (max-width: 800px) {
  .hero-grid, .tool-layout { grid-template-columns: 1fr; }
  .system-note { max-width: 500px; }
  .category-grid { grid-template-columns: 1fr; }
  .proof-strip { grid-template-columns: repeat(2, 1fr); }
  .proof-strip div:nth-child(2) { border-right: 0; }
  .proof-strip div:nth-child(-n+2) { border-bottom: 1px solid var(--border); }
  .tool-aside { position: static; }
}

@media (max-width: 620px) {
  .container { width: min(calc(100% - 28px), var(--max)); }
  .header-inner { min-height: 62px; gap: 10px; }
  .site-nav { gap: 0; }
  .site-nav a { padding: 7px 6px; font-size: .79rem; }
  .site-nav a:nth-of-type(3) { display: none; }
  .theme-toggle { min-width: 34px; padding: 7px; }
  .wordmark { font-size: .95rem; }
  .tool-grid, .form-grid { grid-template-columns: 1fr; }
  .tool-card, .tool-card:nth-child(odd), .tool-card:nth-child(even) { padding: 20px 36px 20px 0; border-right: 0; }
  .tool-card::after, .tool-card:nth-child(odd)::after { right: 5px; top: 19px; }
  .field-full { grid-column: auto; }
  .result-details { grid-template-columns: 1fr; }
  .section-head { display: block; }
  .section-head .text-link { display: inline-block; margin-top: 12px; }
  .search-box input { padding-right: 15px; }
  .search-hint { display: none; }
  .footer-inner { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; }
}