:root {
  color-scheme: dark;
  --bg: #0a0a0a;
  --surface: #141414;
  --surface-raised: #1b1b1b;
  --border: #292929;
  --text: #f7f7f7;
  --muted: #a3a3a3;
  --subtle: #777;
  --gold: #f5c518;
  --green: #3bd675;
  --red: #ff6b6b;
  --radius: 18px;
  --shadow: 0 18px 60px rgb(0 0 0 / 30%);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 50% -20%, rgb(245 197 24 / 10%), transparent 34rem),
    var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
}

.container {
  width: min(100% - 32px, 760px);
  margin-inline: auto;
}

.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;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 20;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--gold);
  color: #111;
  font-weight: 700;
  text-decoration: none;
  transform: translateY(-150%);
}

.skip-link:focus {
  transform: translateY(0);
}

.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 76px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border: 1px solid rgb(245 197 24 / 35%);
  border-radius: 11px;
  background: rgb(245 197 24 / 10%);
  color: var(--gold);
  font-weight: 800;
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  line-height: 1.2;
}

.brand small {
  color: var(--subtle);
  font-size: 0.75rem;
}

.nav-link {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px 12px;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 650;
  text-decoration: none;
}

.nav-link:hover {
  border-color: var(--gold);
  color: var(--gold);
}

:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 3px;
}

.hero {
  padding: 48px 0 34px;
  text-align: center;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 16px;
  border: 1px solid rgb(245 197 24 / 18%);
  border-radius: 999px;
  padding: 6px 12px;
  background: rgb(245 197 24 / 7%);
  color: var(--gold);
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 640px;
  margin: 0 auto;
  font-size: clamp(2rem, 7vw, 3.4rem);
  line-height: 1.05;
  letter-spacing: -0.045em;
}

.hero p {
  max-width: 610px;
  margin: 18px auto 0;
  color: var(--muted);
  font-size: clamp(0.98rem, 3vw, 1.08rem);
}

.calculator,
.result-card,
.guide,
.explanation,
.faq {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}

.calculator {
  padding: clamp(22px, 5vw, 32px);
  text-align: center;
  box-shadow: var(--shadow);
}

.input-label {
  display: block;
  margin-bottom: 12px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 750;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.amount-input {
  position: relative;
  width: min(100%, 420px);
  margin-inline: auto;
}

.amount-input > span {
  position: absolute;
  top: 50%;
  left: 18px;
  color: var(--gold);
  font-size: 1.4rem;
  font-weight: 800;
  transform: translateY(-50%);
  pointer-events: none;
}

.amount-input input {
  width: 100%;
  border: 1px solid #353535;
  border-radius: 14px;
  padding: 17px 18px 17px 46px;
  background: #0d0d0d;
  color: var(--text);
  font: 750 clamp(1.6rem, 7vw, 2.2rem) ui-monospace, SFMono-Regular, Menlo, monospace;
}

.amount-input input:focus {
  border-color: var(--gold);
  outline: 3px solid rgb(245 197 24 / 12%);
}

.amount-input input:invalid {
  border-color: var(--red);
}

.amount-input input::placeholder {
  color: #444;
}

.input-help,
.privacy-note {
  margin: 10px 0 0;
  color: var(--subtle);
  font-size: 0.78rem;
}

.privacy-note {
  color: #86c99d;
}

.results {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.result-card {
  position: relative;
  overflow: hidden;
  padding: 22px;
}

.result-card::before {
  position: absolute;
  inset: 0 0 auto;
  height: 3px;
  content: "";
}

.result-card--bhe::before {
  background: linear-gradient(90deg, var(--gold), #ff8c00);
}

.result-card--invoice::before {
  background: linear-gradient(90deg, var(--green), #159447);
}

.result-card header {
  display: flex;
  align-items: center;
  gap: 12px;
}

.card-icon {
  display: grid;
  width: 42px;
  height: 42px;
  flex: 0 0 auto;
  place-items: center;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-raised);
}

.result-card h2 {
  margin: 0;
  font-size: 1rem;
}

.result-card header p {
  margin: 2px 0 0;
  color: var(--muted);
  font-size: 0.78rem;
}

.primary-result {
  margin: 20px 0 12px;
  border: 1px solid var(--border);
  border-radius: 13px;
  padding: 16px;
  background: #0d0d0d;
  text-align: center;
}

.primary-result span {
  display: block;
  margin-bottom: 5px;
  color: var(--subtle);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.primary-result strong {
  color: var(--gold);
  font: 750 clamp(1.35rem, 5vw, 1.75rem) ui-monospace, SFMono-Regular, Menlo, monospace;
}

.result-card--invoice .primary-result strong {
  color: var(--green);
}

.result-card dl {
  display: grid;
  gap: 7px;
  margin: 0;
}

.result-card dl div {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  border: 1px solid var(--border);
  border-radius: 9px;
  padding: 9px 11px;
  background: #0d0d0d;
}

.result-card dt {
  color: var(--muted);
  font-size: 0.78rem;
}

.result-card dd {
  margin: 0;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.82rem;
  font-weight: 700;
}

.negative {
  color: var(--red);
}

.guide,
.explanation,
.faq {
  margin-top: 16px;
  padding: clamp(22px, 5vw, 30px);
}

.guide h2,
.explanation h2,
.faq h2 {
  margin: 0 0 18px;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.guide-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.guide-grid article {
  border: 1px solid var(--border);
  border-left: 3px solid var(--gold);
  border-radius: 12px;
  padding: 16px;
  background: #0d0d0d;
}

.guide-grid article:last-child {
  border-left-color: var(--green);
}

.guide-grid h3 {
  margin: 0 0 8px;
  font-size: 0.95rem;
}

.guide-grid p,
.explanation p,
.faq p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.guide-grid strong {
  color: var(--text);
}

.sii-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 18px;
  border-radius: 10px;
  padding: 11px 15px;
  background: var(--text);
  color: #111;
  font-size: 0.86rem;
  font-weight: 750;
  text-decoration: none;
}

.sii-link:hover {
  background: var(--gold);
}

.explanation p + p {
  margin-top: 12px;
}

.faq details {
  border-top: 1px solid var(--border);
  padding: 14px 0;
}

.faq details:last-child {
  padding-bottom: 0;
}

.faq summary {
  cursor: pointer;
  font-weight: 700;
}

.faq details p {
  padding-top: 10px;
}

.site-footer {
  margin-top: 36px;
  border-top: 1px solid var(--border);
  padding: 25px 0 36px;
  color: var(--subtle);
  text-align: center;
  font-size: 0.78rem;
}

.site-footer p {
  margin: 4px 0;
}

.site-footer a {
  color: var(--muted);
}

@media (max-width: 640px) {
  .hero {
    padding-top: 34px;
  }

  .results,
  .guide-grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
  }
}

@media print {
  :root {
    color-scheme: light;
  }

  body {
    background: #fff;
    color: #000;
  }

  .navbar,
  .sii-link,
  .site-footer {
    display: none;
  }

  .calculator,
  .result-card,
  .guide,
  .explanation,
  .faq {
    border-color: #bbb;
    background: #fff;
    box-shadow: none;
  }
}