:root {
  color-scheme: dark;
  --bg: #0c0e12;
  --panel: #15181e;
  --panel-2: #1a1e25;
  --ink: #f4f0e8;
  --muted: #a9adb6;
  --line: #303640;
  --accent: #f5a623;
  --accent-soft: rgba(245, 166, 35, 0.13);
  --good: #79d29d;
  --danger: #ff8e7a;
  --radius: 18px;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.38);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    radial-gradient(circle at 85% -10%, rgba(245,166,35,.12), transparent 32rem),
    radial-gradient(circle at -10% 30%, rgba(72,112,255,.08), transparent 32rem),
    var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.55;
}
button, input { font: inherit; }
a { color: inherit; }

.site-header {
  width: min(1180px, calc(100% - 36px));
  margin: 0 auto;
  padding: 22px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand { display: flex; gap: 12px; align-items: center; text-decoration: none; }
.brand-mark {
  width: 42px; height: 42px; display: grid; place-items: center;
  border: 1px solid var(--line); border-radius: 12px; background: var(--panel);
  color: var(--accent); font-size: 24px; font-weight: 700;
}
.brand strong, .brand small { display: block; }
.brand strong { font-size: 15px; letter-spacing: .01em; }
.brand small { color: var(--muted); font-size: 11px; text-transform: uppercase; letter-spacing: .12em; }
.privacy-pill, .hero-badges span {
  border: 1px solid var(--line); background: rgba(21,24,30,.68); color: var(--muted);
  border-radius: 999px; padding: 8px 12px; font-size: 12px;
}

main { width: min(1180px, calc(100% - 36px)); margin: 0 auto; }
.hero { padding: 76px 0 54px; max-width: 980px; }
.eyebrow, .step-label {
  color: var(--accent); font-size: 12px; text-transform: uppercase;
  letter-spacing: .18em; font-weight: 800; margin: 0 0 12px;
}
h1 { font-size: clamp(40px, 6.4vw, 78px); line-height: .99; letter-spacing: -.055em; margin: 0; max-width: 1050px; }
.hero-copy { max-width: 760px; color: var(--muted); font-size: clamp(17px, 2vw, 21px); margin: 26px 0; }
.hero-badges { display: flex; flex-wrap: wrap; gap: 8px; }

.calculator-shell, .result-section, .guide-section, .faq-section {
  border: 1px solid var(--line); border-radius: 26px; background: rgba(21,24,30,.92);
  box-shadow: var(--shadow); padding: clamp(20px, 4vw, 42px); margin-bottom: 42px;
}
.calculator-heading, .result-header { display: flex; justify-content: space-between; gap: 24px; align-items: flex-start; margin-bottom: 28px; }
h2 { font-size: clamp(28px, 4vw, 46px); letter-spacing: -.035em; line-height: 1.05; margin: 0; }
h3 { margin-top: 0; }
.unit-toggle { padding: 4px; border: 1px solid var(--line); border-radius: 12px; background: #0e1015; display: flex; }
.unit-button { color: var(--muted); background: transparent; border: 0; border-radius: 8px; padding: 9px 14px; cursor: pointer; }
.unit-button.active { background: var(--accent); color: #17120a; font-weight: 800; }

.measurement-grid { display: grid; grid-template-columns: 1fr 42px 1fr; gap: 18px; align-items: center; }
.measurement-card { min-width: 0; border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; background: var(--panel-2); }
.measurement-card legend { padding: 0 8px; font-weight: 800; font-size: 18px; }
.measurement-card legend span { color: var(--accent); margin-right: 6px; }
.measurement-visual { height: 105px; display: grid; place-items: center; position: relative; margin-bottom: 12px; }
.pipe { height: 54px; min-width: 190px; display: grid; place-items: center; font-size: 11px; letter-spacing: .16em; color: var(--muted); border: 4px solid #59616d; background: #2a3038; }
.tool-pipe { border-radius: 5px 18px 18px 5px; }
.hose-pipe { border-radius: 24px; border-style: double; border-width: 7px; }
.dimension-line { position: absolute; bottom: 0; color: var(--accent); width: 50%; text-align: center; border-bottom: 1px solid var(--accent); line-height: 10px; }
.connection-symbol { text-align: center; color: var(--accent); font-size: 30px; font-weight: 300; }
.measurement-card > label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 7px; }
.measurement-input { display: flex; align-items: center; border: 1px solid var(--line); background: #0e1015; border-radius: 12px; overflow: hidden; }
.measurement-input input { width: 100%; border: 0; outline: 0; padding: 15px 16px; color: var(--ink); background: transparent; font-size: 24px; font-weight: 750; }
.unit-label { padding: 0 16px; color: var(--accent); font-weight: 800; }
.measurement-type { display: grid; gap: 8px; margin-top: 14px; }
.measurement-type label { display: flex; gap: 10px; align-items: flex-start; border: 1px solid transparent; border-radius: 11px; padding: 10px; cursor: pointer; }
.measurement-type label:has(input:checked) { border-color: rgba(245,166,35,.45); background: var(--accent-soft); }
.measurement-type input { margin-top: 4px; accent-color: var(--accent); }
.measurement-type strong, .measurement-type small { display: block; }
.measurement-type strong { font-size: 14px; }
.measurement-type small { color: var(--muted); margin-top: 2px; }
.form-actions { display: flex; align-items: center; gap: 18px; margin-top: 26px; }
.primary-button, .merchant-button {
  border: 0; border-radius: 12px; padding: 14px 18px; background: var(--accent);
  color: #191209; text-decoration: none; font-weight: 850; cursor: pointer;
}
.primary-button { min-width: 220px; display: flex; justify-content: space-between; gap: 18px; }
.text-button, .copy-button { border: 0; background: transparent; color: var(--muted); cursor: pointer; text-decoration: underline; text-underline-offset: 4px; }
.form-error { margin-top: 18px; color: var(--danger); border-left: 3px solid var(--danger); padding: 8px 12px; background: rgba(255,142,122,.08); }

.result-section { scroll-margin-top: 16px; }
.confidence-panel { max-width: 430px; text-align: right; }
.confidence-panel p { color: var(--muted); font-size: 13px; margin: 10px 0 0; }
.confidence-badge { display: inline-block; border: 1px solid rgba(121,210,157,.4); background: rgba(121,210,157,.1); color: var(--good); border-radius: 999px; padding: 8px 12px; font-size: 12px; text-transform: uppercase; letter-spacing: .1em; font-weight: 800; }
.confidence-badge[data-level="medium"] { border-color: rgba(245,166,35,.45); background: var(--accent-soft); color: var(--accent); }
.confidence-badge[data-level="low"] { border-color: rgba(255,142,122,.45); background: rgba(255,142,122,.1); color: var(--danger); }
.connection-diagram { display: grid; grid-template-columns: 1fr minmax(180px, .8fr) 1fr; align-items: center; border: 1px solid var(--line); background: #0e1015; border-radius: var(--radius); padding: 24px; margin-bottom: 20px; }
.diagram-end small, .diagram-end strong { display: block; }
.diagram-end small { color: var(--muted); font-size: 10px; letter-spacing: .16em; }
.diagram-end strong { margin-top: 5px; font-size: clamp(16px, 2vw, 23px); }
.diagram-end.right { text-align: right; }
.diagram-arrow { text-align: center; color: var(--accent); font-size: 12px; text-transform: uppercase; letter-spacing: .09em; }
.adapter-shape { height: 26px; margin-top: 9px; position: relative; background: linear-gradient(90deg, #65707e 0 35%, #343b45 35% 65%, #65707e 65%); clip-path: polygon(0 20%, 35% 20%, 43% 0, 57% 0, 65% 20%, 100% 20%, 100% 80%, 65% 80%, 57% 100%, 43% 100%, 35% 80%, 0 80%); }
.result-grid { display: grid; grid-template-columns: 1.35fr .65fr; gap: 20px; }
.result-card, .shopping-card, .warning-card { border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel-2); padding: 22px; }
.primary-result ol { padding-left: 22px; }
.primary-result li { margin: 9px 0; font-weight: 700; }
.copy-button { color: var(--accent); padding: 0; }
.airflow-meter { height: 11px; border-radius: 999px; background: #0e1015; overflow: hidden; margin: 22px 0 12px; }
.airflow-meter span { display: block; height: 100%; background: linear-gradient(90deg, var(--danger), var(--accent), var(--good)); border-radius: inherit; }
.result-card p, .shopping-card p { color: var(--muted); }
.shopping-card { display: grid; grid-template-columns: 1fr auto; gap: 24px; align-items: center; margin-top: 20px; }
.merchant-links { display: grid; gap: 9px; min-width: 210px; }
.merchant-button { display: flex; justify-content: space-between; gap: 8px; }
.merchant-button small { font-size: 9px; text-transform: uppercase; letter-spacing: .1em; }
.warning-card { margin-top: 20px; background: rgba(245,166,35,.06); }
.warning-card ul { margin-bottom: 0; color: #d4cec3; }

.guide-section, .faq-section { margin-top: 70px; background: transparent; box-shadow: none; }
.guide-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 34px; }
.guide-grid article { border-top: 1px solid var(--line); padding-top: 18px; }
.guide-number { color: var(--accent); font-size: 12px; font-weight: 800; }
.guide-grid p, details p { color: var(--muted); }
details { border-top: 1px solid var(--line); padding: 18px 0; }
details:last-child { border-bottom: 1px solid var(--line); }
summary { cursor: pointer; font-weight: 750; font-size: 17px; }

footer { width: min(1180px, calc(100% - 36px)); margin: 80px auto 0; padding: 30px 0 50px; border-top: 1px solid var(--line); display: grid; grid-template-columns: 1fr 1fr; gap: 30px; color: var(--muted); font-size: 13px; }
footer strong { color: var(--ink); }
.footer-note { text-align: right; }

@media (max-width: 820px) {
  .privacy-pill { display: none; }
  .hero { padding-top: 48px; }
  .calculator-heading, .result-header { flex-direction: column; }
  .confidence-panel { max-width: none; text-align: left; }
  .measurement-grid { grid-template-columns: 1fr; }
  .connection-symbol { transform: rotate(45deg); height: 22px; }
  .connection-diagram { grid-template-columns: 1fr; gap: 16px; text-align: center; }
  .diagram-end.right { text-align: center; }
  .result-grid, .shopping-card, .guide-grid, footer { grid-template-columns: 1fr; }
  .merchant-links { min-width: 0; }
  .footer-note { text-align: left; }
}

@media (max-width: 520px) {
  main, .site-header, footer { width: min(100% - 22px, 1180px); }
  h1 { font-size: 42px; }
  .calculator-shell, .result-section, .guide-section, .faq-section { padding: 18px; border-radius: 18px; }
  .measurement-card { padding: 15px; }
  .pipe { min-width: 150px; }
  .form-actions { align-items: stretch; flex-direction: column; }
  .primary-button { width: 100%; }
}