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

:root {
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
  --font-display: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;

  /* ── Neutral ink + surfaces (shared by both themes) ── */
  --ink-1: #15171C;
  --ink-2: #555C66;
  --ink-3: #868D97;
  --ink-4: #AEB4BD;
  --border-1: #E7E9ED;
  --border-2: #D6DAE0;
  --surface: #FFFFFF;

  /* ── Semantic: positive / negative (financial clarity, shared) ── */
  --pos: #0B7A5E;
  --pos-strong: #075F49;
  --pos-soft: #E7F4EF;
  --pos-mid: #B4E1D2;
  --pos-ink: #064A38;
  --neg: #B4452A;
  --neg-ink: #8A3520;

  --rk: 1;
  --radius-sm: calc(8px * var(--rk));
  --radius-md: calc(11px * var(--rk));
  --radius-lg: calc(16px * var(--rk));
  --radius-xl: calc(20px * var(--rk));

  --shadow-1: 0 1px 2px rgba(20,26,40,0.04), 0 6px 16px -10px rgba(20,26,40,0.12);
  --shadow-2: 0 2px 6px rgba(20,26,40,0.05), 0 18px 40px -18px rgba(20,26,40,0.22);

  /* ── Theme A · Bilt Blue (default) ── */
  --accent: #1A6BC8;
  --accent-strong: #1257A8;
  --accent-press: #0D4285;
  --accent-soft: #EAF2FD;
  --accent-mid: #B8D5F7;
  --accent-ink: #0C3470;
  --page-bg: #F2F6FD;
  --page-tint: #E5EFF9;
}

[data-theme="bilt"] {
  /* ── Theme B · Bilt · dark mode · deep navy + pale-blue primary (brand-true) ── */
  --accent: #ADCBF5;
  --accent-strong: #C2D8F8;
  --accent-press: #93B9F0;
  --accent-soft: #18222F;
  --accent-mid: #27384F;
  --accent-ink: #BCD3F7;

  --ink-1: #FFFFFF;
  --ink-2: #AEB6C2;
  --ink-3: #79828F;
  --ink-4: #565E6B;
  --border-1: #222B37;
  --border-2: #2E3845;
  --surface: #141A24;

  --pos: #35D08A;
  --pos-strong: #2BB377;
  --neg: #F0795F;
  --neg-ink: #F0795F;

  --page-bg: #0A0D14;
  --page-tint: #121A28;
  --shadow-1: 0 1px 2px rgba(0,0,0,0.4), 0 18px 40px -22px rgba(0,0,0,0.7);
  --shadow-2: 0 2px 6px rgba(0,0,0,0.4), 0 28px 60px -24px rgba(0,0,0,0.75);
}

html { -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  color: var(--ink-1);
  font-size: 16px;
  line-height: 1.6;
}

/* ── Shared layout ── */

.page-bg {
  background:
    radial-gradient(120% 60% at 50% -10%, var(--page-tint) 0%, var(--page-bg) 55%) no-repeat,
    var(--page-bg);
  min-height: 100vh;
  padding: 0 1.5rem;
}
.site { max-width: 760px; margin: 0 auto; padding: 2.25rem 0 4rem; }

/* ── Nav ── */

.nav {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1.25rem; flex-wrap: wrap;
  margin-bottom: 3rem;
}
.nav-logo-group { display: flex; flex-direction: column; gap: 3px; }
.nav-logo {
  font-family: var(--font-display);
  font-size: 24px; font-weight: 700; letter-spacing: -0.02em;
  color: var(--ink-1); line-height: 1;
}
.nav-logo .teal { color: var(--accent); }
.nav-tagline {
  font-size: 13px; color: var(--ink-3);
  letter-spacing: 0.01em; line-height: 1;
}
.nav-links { display: flex; gap: 1.75rem; align-items: center; }
.nav-link {
  font-size: 15px; font-weight: 500; color: var(--ink-2);
  text-decoration: none; cursor: pointer; transition: color 0.12s;
}
.nav-link:hover { color: var(--ink-1); }
.nav-link.active { color: var(--ink-1); font-weight: 600; text-decoration: underline; text-decoration-color: var(--accent); text-decoration-thickness: 3px; text-underline-offset: 6px; }
.nav-cta {
  font-size: 14px; font-weight: 600; color: var(--surface);
  background: var(--accent); border: none;
  border-radius: var(--radius-sm); padding: 9px 16px;
  cursor: pointer; font-family: var(--font-sans);
  text-decoration: none; white-space: nowrap;
  transition: background 0.12s;
}
.nav-cta:hover { background: var(--accent-strong); }

.theme-btn {
  width: 38px; height: 38px; flex-shrink: 0;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 999px; border: 1px solid var(--border-2);
  background: var(--surface); color: var(--ink-2); cursor: pointer;
  transition: background 0.12s, border-color 0.12s, color 0.12s;
}
.theme-btn:hover { color: var(--ink-1); border-color: var(--ink-3); }
.theme-btn svg { width: 18px; height: 18px; display: block; }
.theme-btn .ic-sun { display: none; }
[data-theme="bilt"] .theme-btn .ic-moon { display: none; }
[data-theme="bilt"] .theme-btn .ic-sun { display: block; }

/* ── Footer ── */

.footer { margin-top: 3.5rem; padding-top: 1.75rem; border-top: 1px solid var(--border-1); display: flex; flex-direction: column; gap: 8px; }
.footer-note { font-size: 16px; color: var(--ink-2); line-height: 1.6; margin-bottom: 0.75rem; }
.footer-note strong { color: var(--ink-1); font-weight: 600; }
.footer-note a { color: var(--ink-2); font-weight: 500; text-decoration: underline; text-decoration-color: var(--border-2); text-underline-offset: 2px; }
.footer-note a:hover { color: var(--ink-1); text-decoration-color: var(--ink-3); }
.footer-line { font-size: 13px; color: var(--ink-3); line-height: 1.6; }
.footer-line a { color: var(--accent); text-decoration: none; }
.footer-line a:hover { text-decoration: underline; }
.footer-links { display: flex; flex-wrap: wrap; gap: 1.25rem; margin-top: 12px; }
.footer-links a { font-size: 13px; font-weight: 500; color: var(--accent); text-decoration: none; cursor: pointer; }
.footer-links a:hover { text-decoration: underline; }

/* ══════════════════════════════
   Calculator page (index.html)
   ══════════════════════════════ */

.hero { margin-bottom: 2.5rem; max-width: 620px; }
.hero-eyebrow { font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--accent); margin-bottom: 0.85rem; }
.hero-headline { font-family: var(--font-display); font-size: clamp(30px, 6vw, 42px); font-weight: 600; letter-spacing: -0.03em; line-height: 1.08; color: var(--ink-1); margin-bottom: 0.85rem; text-wrap: balance; }
.hero-sub { font-size: 17px; color: var(--ink-2); line-height: 1.6; }

.calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.75rem; align-items: start; }
.input-panel { display: flex; flex-direction: column; }

.field { display: flex; flex-direction: column; gap: 7px; margin-bottom: 1.35rem; }
.field label { font-size: 12px; font-weight: 600; color: var(--ink-3); letter-spacing: 0.06em; text-transform: uppercase; }
.field input, .field select {
  font-size: 16px; color: var(--ink-1);
  background: var(--surface);
  border: 1px solid var(--border-2);
  border-radius: var(--radius-sm);
  padding: 11px 13px; width: 100%; font-family: var(--font-sans);
  transition: border-color 0.12s, box-shadow 0.12s;
}
.field input::placeholder { color: var(--ink-4); }
.field input:focus, .field select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.field-hint { font-size: 12px; color: var(--ink-3); }

.section-divider { height: 1px; background: var(--border-1); margin: 1.35rem 0; }

.toggle-row {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; padding: 13px 15px; background: var(--accent-soft);
  border: 1px solid var(--accent-mid);
  border-radius: var(--radius-sm);
  cursor: pointer; margin-bottom: 1.35rem;
  transition: background 0.12s, border-color 0.12s;
}
.toggle-row.off { background: var(--surface); border-color: var(--border-1); }
.toggle-label { font-size: 14px; font-weight: 500; color: var(--ink-1); }
.toggle { width: 34px; height: 20px; background: var(--border-2); border-radius: 100px; position: relative; transition: background 0.15s; flex-shrink: 0; }
.toggle.on { background: var(--accent); }
.toggle::after { content: ''; position: absolute; top: 2px; left: 2px; width: 16px; height: 16px; background: white; border-radius: 50%; transition: left 0.15s; box-shadow: 0 1px 2px rgba(0,0,0,0.2); }
.toggle.on::after { left: 16px; }

.disclosure-trigger { display: flex; align-items: center; justify-content: space-between; gap: 12px; cursor: pointer; padding: 11px 0; user-select: none; }
.disclosure-trigger:hover .dt-label { color: var(--ink-1); }
.dt-label { font-size: 14px; color: var(--ink-2); font-weight: 600; }
.dt-hint { font-size: 13px; color: var(--ink-3); margin-top: 1px; }
.disclosure-inner { padding-top: 0.85rem; padding-bottom: 0.5rem; }
.disclosure { overflow: hidden; max-height: 0; transition: max-height 0.35s ease; }
.disclosure.open { max-height: 1400px; }
.dt-chevron {
  color: var(--ink-3);
  display: inline-flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  transition: transform 0.2s, color 0.2s;
}
.dt-chevron svg { display: block; }
.disclosure-trigger:hover .dt-chevron { color: var(--accent); }
.dt-chevron.open { transform: rotate(180deg); }


.housing-module { border: 1px solid var(--border-1); border-radius: var(--radius-md); overflow: hidden; margin-bottom: 1.35rem; background: var(--surface); }
.hm-header { padding: 11px 14px; background: var(--accent-soft); border-bottom: 1px solid var(--accent-mid); display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.hm-title { font-size: 12px; font-weight: 600; color: var(--accent-ink); text-transform: uppercase; letter-spacing: 0.06em; }
.hm-badge { font-size: 12px; color: var(--accent-ink); background: var(--accent-mid); border-radius: 100px; padding: 3px 11px; font-weight: 600; white-space: nowrap; }
.hm-body { padding: 1.15rem; display: flex; flex-direction: column; gap: 12px; }
.hm-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; align-items: end; }
.threshold-card { background: var(--page-tint); border-radius: var(--radius-sm); padding: 10px 12px; }
.tc-label { font-size: 11px; color: var(--ink-3); text-transform: uppercase; letter-spacing: 0.06em; font-weight: 600; margin-bottom: 4px; }
.tc-val { font-family: var(--font-display); font-size: 21px; font-weight: 600; letter-spacing: -0.02em; color: var(--ink-1); }
.tc-sub { font-size: 11px; color: var(--ink-3); margin-top: 2px; }
.hm-insight { font-size: 14px; line-height: 1.55; color: var(--ink-2); }
.hm-insight strong { color: var(--accent); font-weight: 600; }

.opt-toggle { display: flex; align-items: center; gap: 9px; cursor: pointer; font-size: 13px; color: var(--ink-3); user-select: none; }
.opt-toggle:hover { color: var(--ink-2); }
.opt-box { width: 18px; height: 18px; border: 1px solid var(--border-2); border-radius: 5px; display: flex; align-items: center; justify-content: center; background: var(--surface); flex-shrink: 0; font-size: 11px; color: var(--surface); }
.opt-box.on { background: var(--accent); border-color: var(--accent); }
.progress-track { height: 7px; background: var(--accent-soft); border-radius: 100px; overflow: hidden; margin-top: 6px; }
.progress-fill { height: 100%; border-radius: 100px; background: var(--accent); transition: width 0.3s; }
.progress-fill.over { background: var(--pos); }
.progress-fill.low { background: var(--neg); }
.progress-meta { display: flex; justify-content: space-between; font-size: 12px; color: var(--ink-3); margin-top: 6px; }

.partner-section { margin-bottom: 1.35rem; }
.ps-label { font-size: 12px; font-weight: 600; color: var(--ink-3); letter-spacing: 0.06em; text-transform: uppercase; margin-bottom: 10px; }
.chip-grid { display: flex; flex-wrap: wrap; gap: 7px; margin-bottom: 10px; }
.chip { display: flex; align-items: center; gap: 7px; padding: 6px 12px 6px 8px; border: 1px solid var(--border-2); border-radius: 100px; cursor: pointer; background: var(--surface); user-select: none; transition: border-color 0.12s, background 0.12s; }
.chip:hover { border-color: var(--accent); }
.chip.selected { border: 1.5px solid var(--accent); background: var(--accent-soft); }
.chip-logo { width: 18px; height: 18px; border-radius: 4px; flex-shrink: 0; object-fit: contain; }
.chip-name { font-size: 13px; color: var(--ink-1); white-space: nowrap; }
.chip-cpp { font-size: 11px; color: var(--accent-ink); font-weight: 600; background: var(--accent-mid); border-radius: 100px; padding: 1px 7px; opacity: 0; transition: opacity 0.15s; white-space: nowrap; }
.chip.selected .chip-cpp { opacity: 1; }
.show-more-link { font-size: 13px; font-weight: 500; color: var(--accent); cursor: pointer; }
.show-more-link:hover { text-decoration: underline; }

.blend-bar { background: var(--surface); border: 1px solid var(--border-1); border-radius: var(--radius-md); padding: 12px 14px; display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 1.35rem; }
.blend-left-text { font-size: 14px; font-weight: 500; color: var(--ink-2); }
.blend-left-sub { font-size: 12px; color: var(--ink-3); margin-top: 2px; }
.cpp-override { font-family: var(--font-display); font-size: 21px; font-weight: 600; background: none; border: none; border-bottom: 1.5px solid var(--border-2); color: var(--accent); width: 58px; text-align: right; padding: 0 2px; letter-spacing: -0.02em; }
.cpp-override:focus { outline: none; border-bottom-color: var(--accent); }
.cpp-unit { font-size: 13px; color: var(--ink-2); }

/* Result panel */
.result-panel { background: var(--surface); border: 1px solid var(--border-1); border-radius: var(--radius-lg); padding: 1.6rem; position: sticky; top: 1.5rem; box-shadow: var(--shadow-1); }
.verdict { margin-bottom: 1.5rem; }
.verdict-label { font-size: 11px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 0.55rem; }
.verdict-main { font-family: var(--font-display); font-size: 32px; font-weight: 600; letter-spacing: -0.03em; line-height: 1.05; }
.verdict-main.yes { color: var(--pos); }
.verdict-main.no { color: var(--neg); }
.verdict-main.neutral { color: var(--ink-2); }
.verdict-sub { font-size: 14px; color: var(--ink-2); margin-top: 8px; line-height: 1.5; }
.verdict-sub strong { color: var(--ink-1); font-weight: 600; }
.breakdown { display: flex; flex-direction: column; gap: 11px; margin-bottom: 1.25rem; }
.br-row { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; }
.br-k { font-size: 14px; color: var(--ink-2); white-space: nowrap; }
.br-v { font-family: var(--font-display); font-size: 14px; font-weight: 500; color: var(--ink-1); font-variant-numeric: tabular-nums; }
.br-v.pos { color: var(--pos); }
.br-v.neg { color: var(--neg); }
.result-divider { height: 1px; background: var(--border-1); margin: 1rem 0; }
.net-row { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; margin-bottom: 1.5rem; }
.net-k { font-size: 15px; font-weight: 600; color: var(--ink-1); }
.net-v { font-family: var(--font-display); font-size: 28px; font-weight: 600; letter-spacing: -0.02em; font-variant-numeric: tabular-nums; color: var(--pos); }
.net-v.neg { color: var(--neg); }
.cpp-context { font-size: 12px; color: var(--ink-3); margin-bottom: 1.4rem; line-height: 1.5; padding: 10px 12px; background: var(--page-tint); border-radius: var(--radius-sm); }
.apply-btn { display: block; width: 100%; padding: 13px; background: var(--accent); color: var(--surface); border: none; border-radius: var(--radius-sm); font-size: 15px; font-weight: 600; cursor: pointer; font-family: var(--font-sans); text-decoration: none; text-align: center; transition: background 0.12s; }
.apply-btn:hover { background: var(--accent-strong); }
.apply-btn:active { background: var(--accent-press); }
.apply-sub { font-size: 12px; color: var(--ink-3); text-align: center; margin-top: 9px; }

/* ══════════════════════════════
   About page (about.html)
   ══════════════════════════════ */

.about .nav { margin-bottom: 4rem; }

.beat { padding: 2.25rem 0; border-top: 1px solid var(--border-1); }
.beat:last-of-type { border-bottom: 1px solid var(--border-1); }
.beat-num { font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--accent); margin-bottom: 1.1rem; }
.beat-text { font-size: 24px; font-weight: 400; letter-spacing: -0.02em; line-height: 1.45; color: var(--ink-1); text-wrap: pretty; }
.beat-text strong { font-weight: 600; }
.beat-text .muted { color: var(--ink-2); }

.examples { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 1.4rem; }
.example-pill { font-size: 14px; font-weight: 500; color: var(--accent-ink); background: var(--accent-soft); border: 1px solid var(--accent-mid); border-radius: 100px; padding: 6px 15px; }

.caveat {
  margin-top: 3rem;
  padding: 1.4rem 1.6rem;
  background: var(--surface);
  border: 1px solid var(--border-1);
  border-left: 3px solid var(--neg);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  box-shadow: var(--shadow-1);
}
.caveat-label { font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--neg); margin-bottom: 0.6rem; }
.caveat-text { font-size: 16px; color: var(--ink-2); line-height: 1.6; }
.caveat-text strong { color: var(--ink-1); font-weight: 600; }

.cta-block { margin-top: 3rem; display: flex; align-items: center; flex-wrap: wrap; gap: 1.25rem; }
.cta-btn { padding: 13px 24px; background: var(--accent); color: var(--surface); border: none; border-radius: var(--radius-sm); font-size: 15px; font-weight: 600; cursor: pointer; font-family: var(--font-sans); text-decoration: none; display: inline-block; transition: background 0.12s; }
.cta-btn:hover { background: var(--accent-strong); }
.cta-secondary { font-size: 15px; color: var(--ink-2); }
.cta-secondary a { color: var(--accent); text-decoration: none; font-weight: 500; }
.cta-secondary a:hover { text-decoration: underline; }

/* ── Accessibility ── */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }

/* ══════════════════════════════
   Responsive · mobile
   ══════════════════════════════ */

@media (max-width: 720px) {
  .page-bg { padding: 0 1.15rem; }
  .site { padding: 1.5rem 0 3rem; }

  .nav { margin-bottom: 2.25rem; }
  .nav-links { gap: 1.25rem; width: 100%; }
  .nav-cta { margin-left: auto; }

  .hero { margin-bottom: 2rem; }

  .calc-grid { grid-template-columns: 1fr; gap: 1.5rem; }
  .result-panel { position: static; }
}

@media (max-width: 420px) {
  .nav-links { gap: 1rem; }
  .nav-link { font-size: 14px; }
  .field-row { grid-template-columns: 1fr; }
  .hm-row { grid-template-columns: 1fr; }
}

/* ══════════════════════════════
   Surface treatment (tweakable via data-surface)
   ══════════════════════════════ */

/* Bordered — flat hairline, no elevation (editorial, minimal) */
[data-surface="bordered"] .result-panel,
[data-surface="bordered"] .housing-module,
[data-surface="bordered"] .blend-bar,
[data-surface="bordered"] .caveat {
  background: var(--surface);
  border: 1px solid var(--border-2);
  box-shadow: none;
}
[data-surface="bordered"] .caveat { border-left: 3px solid var(--neg); }

/* Floating — borderless, lifted on shadow (app-like, premium) */
[data-surface="floating"] .result-panel {
  border-color: transparent;
  box-shadow: var(--shadow-2);
}
[data-surface="floating"] .housing-module,
[data-surface="floating"] .blend-bar {
  border-color: transparent;
  box-shadow: var(--shadow-1);
}
[data-surface="floating"] .caveat {
  border: 1px solid transparent;
  border-left: 3px solid var(--neg);
  box-shadow: var(--shadow-2);
}

/* Solid — filled tinted blocks, no border or shadow (bold, blocky) */
[data-surface="solid"] .result-panel,
[data-surface="solid"] .housing-module,
[data-surface="solid"] .blend-bar,
[data-surface="solid"] .caveat {
  background: var(--page-tint);
  border-color: transparent;
  box-shadow: none;
}
[data-surface="solid"] .caveat { border-left: 3px solid var(--neg); }

.hidden {
  display: none;
}