@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap");

:root {
  --bg: #f4faff;
  --bg-accent: #e7f6ff;
  --surface: #f8fbff;
  --surface-strong: #ffffff;
  --surface-soft: #eef8ff;
  --line: rgba(145, 184, 203, 0.15);
  --text: #0a3747;
  --muted: #3e6475;
  --primary: #2f5f9c;
  --primary-deep: #20538f;
  --primary-soft: #d5e3ff;
  --primary-surface: #d5e3ff;
  --success: #1e7a52;
  --error: #9f403d;
  --error-soft: #fff1f1;
  --shadow: 0 20px 40px rgba(10, 55, 71, 0.06);
  --shadow-soft: 0 0 0 rgba(0, 0, 0, 0);
  --radius-sm: 0.35rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --container: 72rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: "Inter", "Segoe UI", sans-serif;
  background: linear-gradient(180deg, #f9fcff 0%, var(--bg) 100%);
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  display: block;
  max-width: 100%;
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

[hidden] {
  display: none !important;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -3rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--primary);
  color: white;
  z-index: 1000;
}

.skip-link:focus {
  top: 1rem;
}

.site-header {
  padding-top: 1rem;
  background: transparent;
}

.container {
  width: min(calc(100% - 2rem), var(--container));
  margin: 0 auto;
}

.header-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: 2.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.brand-mark {
  display: none;
}

.brand-text {
  font-size: 0.82rem;
  color: var(--primary);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-link {
  padding: 0.2rem 0.45rem;
  border-radius: var(--radius-sm);
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
  transition: background-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  background: transparent;
  color: var(--primary);
  outline: none;
}

.nav-link[aria-current="page"] {
  color: var(--primary);
}

.page-main {
  padding: 1.25rem 0 4rem;
}

.hero-panel,
.content-panel,
.legal-panel {
  position: relative;
  overflow: visible;
  border: 0;
  border-radius: var(--radius-lg);
  background: var(--bg-accent);
  box-shadow: var(--shadow-soft);
}

.hero-panel {
  padding: 0;
  background: transparent;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.85rem;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: var(--primary);
}

.eyebrow::before {
  content: "";
  width: 0.45rem;
  height: 0.45rem;
  border-radius: 999px;
  background: rgba(47, 95, 156, 0.22);
}

.hero-panel > .eyebrow::before {
  display: none;
}

.hero-title {
  margin: 0;
  font-size: clamp(2rem, 6vw, 3rem);
  line-height: 1.02;
  letter-spacing: -0.02em;
}

.hero-copy {
  max-width: 40rem;
  margin: 0.75rem 0 0;
  color: var(--muted);
  font-size: clamp(0.98rem, 2vw, 1.02rem);
  line-height: 1.65;
}

.calculator-layout {
  display: grid;
  gap: 1.5rem;
  margin-top: 1.25rem;
}

.calculator-card,
.result-card,
.content-panel,
.legal-panel {
  padding: 1.5rem;
}

.calculator-card,
.result-card {
  border: 1px solid rgba(145, 184, 203, 0.15);
  border-radius: var(--radius-lg);
}

.calculator-card {
  background: var(--surface-strong);
  box-shadow: none;
}

.result-card {
  position: relative;
  overflow: hidden;
  background: var(--primary-surface);
  box-shadow: var(--shadow);
}

.result-card[data-state="invalid"] {
  background: #fceeed;
}

.result-card::before {
  display: none;
}

.result-card > * {
  position: relative;
  z-index: 1;
}

.section-title {
  margin: 0 0 0.45rem;
  font-size: clamp(1.35rem, 3vw, 1.7rem);
  letter-spacing: -0.03em;
}

.section-copy {
  margin: 0;
  color: var(--muted);
  line-height: 1.65;
}

.field-grid {
  display: grid;
  gap: 0.85rem;
  margin-top: 1.25rem;
}

.field {
  display: grid;
  gap: 0.45rem;
}

.field-label {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--muted);
}

.field-hint {
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.45;
}

.input,
.select {
  width: 100%;
  min-height: 2.9rem;
  border: 1px solid rgba(145, 184, 203, 0.18);
  border-radius: var(--radius-md);
  background: var(--surface-strong);
  color: var(--text);
  padding: 0.8rem 0.85rem;
  box-shadow: none;
  transition: border-color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.input::placeholder {
  color: rgba(62, 100, 117, 0.55);
}

.input:focus-visible,
.select:focus-visible,
.segment:focus-visible,
.choice-pill:focus-visible,
.primary-button:focus-visible,
.ghost-button:focus-visible,
.subtle-button:focus-visible,
.inline-link:focus-visible,
summary:focus-visible {
  outline: 0;
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(47, 95, 156, 0.18);
}

.input[aria-invalid="true"] {
  border-color: rgba(159, 64, 61, 0.45);
  background: var(--error-soft);
}

.segmented {
  display: grid;
  gap: 0.35rem;
  margin-top: 1.25rem;
  padding: 0.35rem;
  border-radius: var(--radius-lg);
  background: rgba(213, 227, 255, 0.72);
}

.segment {
  border: 0;
  padding: 0.75rem 0.9rem;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--muted);
  font-weight: 700;
  text-align: left;
  transition: background-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.segment.is-active {
  background: rgba(255, 255, 255, 0.98);
  color: var(--primary);
  box-shadow: none;
}

.choice-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
}

.choice-pill {
  border: 1px solid rgba(145, 184, 203, 0.15);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.92);
  color: var(--muted);
  padding: 0.65rem 0.85rem;
  font-weight: 700;
  transition: border-color 160ms ease, background-color 160ms ease, color 160ms ease;
}

.choice-pill.is-active {
  border-color: rgba(47, 95, 156, 0.15);
  background: rgba(255, 255, 255, 1);
  color: var(--primary);
}

.inline-message {
  min-height: 1.4rem;
  margin-top: 0.85rem;
  font-size: 0.88rem;
  line-height: 1.55;
  color: var(--muted);
}

.inline-message[data-tone="error"] {
  color: var(--error);
}

.inline-message[data-tone="success"] {
  color: var(--success);
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 1.25rem;
}

.primary-button,
.ghost-button,
.subtle-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.9rem;
  border-radius: var(--radius-md);
  border: 0;
  padding: 0.8rem 1.15rem;
  font-weight: 700;
  transition: transform 160ms ease, background-color 160ms ease, color 160ms ease, border-color 160ms ease;
}

.primary-button {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-deep) 100%);
  color: white;
  box-shadow: none;
}

.primary-button:hover,
.ghost-button:hover,
.subtle-button:hover {
  transform: none;
}

.ghost-button {
  background: transparent;
  color: var(--primary);
  border: 1px solid rgba(145, 184, 203, 0.15);
}

.subtle-button {
  min-height: 2.7rem;
  padding-inline: 1rem;
  background: rgba(255, 255, 255, 0.76);
  color: var(--muted);
}

.subtle-button[disabled],
.primary-button[disabled] {
  opacity: 0.55;
  cursor: not-allowed;
  transform: none;
}

.result-eyebrow {
  margin: 0;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: rgba(10, 55, 71, 0.68);
}

.result-primary {
  margin: 0.45rem 0 0;
  font-size: clamp(2rem, 8vw, 3.3rem);
  line-height: 0.98;
  letter-spacing: -0.03em;
  color: #1f528f;
}

.result-helper {
  margin: 0.85rem 0 0;
  color: rgba(10, 55, 71, 0.8);
  line-height: 1.55;
}

.result-list {
  display: grid;
  gap: 1rem;
  margin: 1.5rem 0 0;
}

.result-row {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  padding: 0;
  border-bottom: 0;
}

.result-row strong {
  font-size: 1rem;
}

.content-grid,
.card-grid,
.related-grid,
.formula-grid,
.example-grid,
.legal-stack {
  display: grid;
  gap: 1rem;
}

.stack-xl {
  display: grid;
  gap: 1.5rem;
}

.content-panel h2,
.content-panel h3,
.legal-panel h1,
.legal-panel h2,
.legal-panel h3 {
  margin: 0 0 0.75rem;
  letter-spacing: -0.03em;
}

.content-panel p,
.legal-panel p,
.content-panel li,
.legal-panel li {
  margin: 0;
  color: var(--muted);
  line-height: 1.65;
}

.content-panel ul,
.legal-panel ul {
  margin: 0;
  padding-left: 1.2rem;
}

.info-card,
.related-card,
.formula-card,
.example-card,
.stat-card {
  padding: 1.1rem;
  border: 1px solid rgba(145, 184, 203, 0.12);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.92);
}

.formula-card {
  background: rgba(255, 255, 255, 0.92);
}

.formula-code {
  display: block;
  margin-top: 0.55rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-md);
  background: rgba(213, 227, 255, 0.55);
  color: var(--primary);
  font-size: clamp(1rem, 3vw, 1.3rem);
  font-weight: 800;
  letter-spacing: -0.03em;
}

.faq-list {
  display: grid;
  gap: 0.65rem;
}

.faq-item {
  border: 0;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.92);
  overflow: hidden;
}

.faq-item summary {
  list-style: none;
  padding: 1rem 1.1rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.faq-item summary::after {
  content: "+";
  color: var(--primary);
  font-weight: 800;
  font-size: 1.1rem;
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-item summary:hover {
  background: rgba(231, 246, 255, 0.8);
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-answer {
  padding: 0 1.1rem 1.1rem;
}

.related-card {
  display: grid;
  gap: 0.45rem;
}

.related-card span {
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
}

.inline-link {
  color: var(--primary);
  font-weight: 700;
}

.source-block {
  display: grid;
  gap: 0.65rem;
  color: var(--muted);
}

.site-footer {
  margin-top: 2rem;
  padding: 1.25rem 0 2rem;
  background: var(--bg-accent);
}

.footer-panel {
  display: grid;
  gap: 0.75rem;
  padding: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
}

.footer-brand {
  display: grid;
  gap: 0.2rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  color: var(--muted);
}

.footer-copy {
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.6;
}

.prose-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.muted {
  color: var(--muted);
}

@media (min-width: 700px) {
  .segmented {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .field-grid.two-up,
  .card-grid.two-up,
  .formula-grid,
  .example-grid,
  .legal-stack {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .related-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .calculator-layout {
    grid-template-columns: minmax(0, 1fr) minmax(18rem, 21rem);
    align-items: start;
  }

  .result-card {
    position: sticky;
    top: 2rem;
  }

  .content-grid {
    grid-template-columns: 1fr;
  }

  .footer-panel {
    grid-template-columns: auto 1fr auto;
    align-items: center;
  }
}

@media (max-width: 699px) {
  .site-nav {
    width: 100%;
    justify-content: flex-start;
  }

  .header-row {
    flex-direction: column;
    align-items: stretch;
    padding-block: 0.3rem 0.8rem;
  }

  .nav-link {
    flex: none;
    text-align: left;
  }

  .action-row > * {
    flex: 1 1 100%;
  }
}