:root {
  color-scheme: dark;
  --bg: #05070d;
  --surface: #101622;
  --surface-strong: #151d2c;
  --text: #f8fafc;
  --muted: #94a3b8;
  --line: rgba(148, 163, 184, 0.22);
  --accent: #7dd3fc;
  --accent-dark: #38bdf8;
  --accent-2: #a78bfa;
  --danger: #fb7185;
  --shadow: 0 28px 80px rgba(0, 0, 0, 0.35);
  --radius: 22px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-height: 100vh; background: radial-gradient(circle at top left, rgba(125, 211, 252, .16), transparent 34%), var(--bg); color: var(--text); line-height: 1.6; }
a { color: inherit; }

.site-header { position: sticky; top: 0; z-index: 10; background: rgba(5, 7, 13, .82); backdrop-filter: blur(16px); }
.nav { max-width: 1120px; margin: 0 auto; padding: 16px 20px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 900; letter-spacing: -0.03em; }
.brand-mark { display: grid; place-items: center; width: 38px; height: 38px; border-radius: 12px; background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #020617; font-size: 1.1rem; }
.nav-links { display: flex; gap: 8px; color: var(--muted); font-size: 0.95rem; flex-wrap: wrap; }
.nav-links a { padding: 9px 12px; border: 1px solid transparent; border-radius: 999px; text-decoration: none; font-weight: 800; }
.nav-links a:hover { color: var(--text); border-color: var(--line); background: rgba(255, 255, 255, .05); }

.section { max-width: 1120px; margin: 0 auto; padding: 72px 20px; }
.hero { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(300px, 0.85fr); gap: 48px; align-items: center; min-height: 620px; }
.eyebrow { margin: 0 0 10px; color: var(--accent); text-transform: uppercase; letter-spacing: 0.12em; font-weight: 900; font-size: 0.78rem; }
h1, h2 { margin: 0; letter-spacing: -0.045em; line-height: 1.05; }
h1 { max-width: 760px; font-size: clamp(3rem, 8vw, 5.8rem); }
h2 { font-size: clamp(2rem, 4vw, 3.1rem); }
.hero-text, .section-heading p, .note p, .tool-link span { color: var(--muted); }
.hero-text { max-width: 680px; margin: 24px 0 0; font-size: 1.18rem; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 30px; }

.button { appearance: none; display: inline-flex; justify-content: center; align-items: center; min-height: 46px; padding: 12px 18px; border: 1px solid transparent; border-radius: 999px; text-decoration: none; font: inherit; font-weight: 900; cursor: pointer; }
.button.primary { background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #020617; }
.button.primary:hover { filter: brightness(1.05); }
.button.secondary { background: rgba(255, 255, 255, .05); border-color: var(--line); color: var(--text); }

.hero-card, .calculator-card, .tool-link, .note { background: linear-gradient(180deg, rgba(255,255,255,.06), rgba(255,255,255,.025)); border: 1px solid var(--line); box-shadow: var(--shadow); border-radius: var(--radius); }
.hero-card { padding: 22px; }
.mock-screen { min-height: 92px; display: flex; align-items: center; justify-content: flex-end; padding: 20px; border-radius: 18px; background: #020617; color: #ffffff; font-size: 2.2rem; font-weight: 900; overflow: hidden; white-space: nowrap; }
.mock-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin-top: 14px; }
.mock-key { appearance: none; display: grid; place-items: center; min-height: 54px; border: 1px solid var(--line); border-radius: 16px; background: rgba(255,255,255,.06); color: var(--text); font: inherit; font-weight: 900; cursor: pointer; transition: transform 120ms ease, background 120ms ease, border-color 120ms ease; }
.mock-key:hover { transform: translateY(-1px); border-color: rgba(125, 211, 252, .42); }
.mock-key:active { transform: translateY(1px); }
.mock-key.operator { background: rgba(125, 211, 252, .14); color: var(--accent); }
.mock-key.equal { grid-row: span 2; background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #020617; }
.mock-key.clear { background: rgba(251, 113, 133, .14); color: #fecdd3; }
.mock-key.zero { grid-column: span 2; }

.intro { padding-top: 24px; }
.tool-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; margin-top: 26px; }
.tool-link { min-height: 150px; padding: 22px; text-decoration: none; display: flex; flex-direction: column; justify-content: space-between; transition: transform 160ms ease, border-color 160ms ease; }
.tool-link:hover { transform: translateY(-3px); border-color: rgba(125, 211, 252, .42); }
.tool-link strong { display: block; font-size: 1.1rem; }

.calculator-section { display: grid; grid-template-columns: 0.8fr 1.2fr; gap: 34px; align-items: start; }
.calculator-section.alt { max-width: none; padding-left: max(20px, calc((100vw - 1120px) / 2 + 20px)); padding-right: max(20px, calc((100vw - 1120px) / 2 + 20px)); background: rgba(255,255,255,.025); }
.section-heading { position: sticky; top: 96px; }
.section-heading p { max-width: 460px; margin: 16px 0 0; }
.calculator-card { padding: 28px; }
.field-grid { display: grid; gap: 16px; }
.field-grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.field-grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
label { display: grid; gap: 8px; margin-bottom: 16px; color: var(--muted); font-weight: 800; font-size: 0.95rem; }
input, select { width: 100%; min-height: 48px; border: 1px solid var(--line); border-radius: 14px; padding: 10px 12px; background: #0b111d; color: var(--text); font: inherit; }
input:focus, select:focus, .mock-key:focus-visible { outline: 3px solid rgba(125, 211, 252, .2); border-color: var(--accent); }
.result { display: block; margin-top: 18px; padding: 18px; border-radius: 18px; background: rgba(125, 211, 252, .1); border: 1px solid rgba(125, 211, 252, .24); color: #dff6ff; font-size: 1.08rem; font-weight: 900; white-space: pre-line; }
.note { margin-top: 72px; margin-bottom: 72px; padding: 34px; }
.site-footer { display: none; }

@media (max-width: 920px) { .hero, .calculator-section { grid-template-columns: 1fr; } .hero { min-height: auto; } .section-heading { position: static; } .tool-grid, .field-grid.three { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 680px) { .nav { align-items: flex-start; flex-direction: column; } .nav-links { width: 100%; overflow-x: auto; padding-bottom: 4px; } .section { padding: 48px 16px; } .tool-grid, .field-grid.two, .field-grid.three { grid-template-columns: 1fr; } .calculator-card { padding: 20px; } h1 { font-size: clamp(2.55rem, 14vw, 4rem); } }