:root {
  --bg: #f7f7f5;
  --surface: rgba(255, 255, 255, 0.82);
  --surface-strong: #ffffff;
  --surface-border: rgba(19, 37, 47, 0.1);
  --text: #0d1216;
  --muted: #5d6e79;
  --accent: #2f6ea5;
  --accent-deep: #255a88;
  --highlight: #c9cccd;
  --shadow: 0 24px 60px rgba(19, 37, 47, 0.12);
  --radius-lg: 28px;
  --radius-md: 18px;
  --radius-sm: 12px;
  --container: 1180px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(47, 110, 165, 0.08), transparent 26%),
    linear-gradient(180deg, #f9f9f7 0%, #f2f2ef 100%);
  font-family: "Avenir Next", Avenir, "Helvetica Neue", Helvetica, Arial, sans-serif;
  line-height: 1.6;
}

a {
  color: inherit;
}

img {
  max-width: 100%;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  padding: 0.75rem 1rem;
  background: var(--accent-deep);
  color: #fff;
  border-radius: 999px;
  z-index: 20;
}

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

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(12px);
  background: rgba(248, 244, 236, 0.78);
  border-bottom: 1px solid rgba(19, 37, 47, 0.08);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.85rem;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 2.75rem;
  height: 2.75rem;
  flex-shrink: 0;
}

.brand-mark img {
  display: block;
  width: 100%;
  height: 100%;
}

.brand-copy {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-copy strong {
  font-size: 0.96rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.brand-copy span {
  color: var(--muted);
  font-size: 0.88rem;
}

.site-nav {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem;
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid rgba(19, 37, 47, 0.08);
  border-radius: 999px;
}

.nav-link {
  text-decoration: none;
  color: var(--muted);
  padding: 0.7rem 1rem;
  border-radius: 999px;
  transition: background-color 180ms ease, color 180ms ease, transform 180ms ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  background: rgba(13, 139, 139, 0.1);
  color: var(--accent-deep);
}

.nav-link.active {
  background: var(--text);
  color: #fff;
}

.hero {
  padding: 2.5rem 0 1.5rem;
}

.hero-secondary {
  padding-bottom: 1rem;
}

.hero-grid {
  display: grid;
  gap: 1.5rem;
  align-items: stretch;
}

.hero-grid-single {
  grid-template-columns: 1fr;
}

.hero-copy,
.calculator-card,
.content-card,
.definition-card {
  border: 1px solid var(--surface-border);
  box-shadow: var(--shadow);
}

.hero-copy,
.content-card {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.92), rgba(255, 255, 255, 0.72));
  border-radius: var(--radius-lg);
  padding: clamp(1.5rem, 2vw, 2.5rem);
}

.hero-copy h1,
.section-heading h2,
.content-card h2,
.calculator-card h3,
.definition-card h3 {
  line-height: 1.1;
  margin: 0;
}

.hero-copy h1 {
  font-size: clamp(2.15rem, 4.4vw, 3.9rem);
  max-width: 11ch;
}

.eyebrow,
.card-kicker {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0 0 1rem;
  color: var(--accent-deep);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.hero-text,
.section-heading p,
.card-copy,
.content-card p,
.definition-card p {
  color: var(--muted);
}

.hero-actions,
.footer-row {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  flex-wrap: wrap;
}

.hero-copy-simple {
  max-width: 58rem;
}

.button,
.text-link {
  transition: transform 180ms ease, background-color 180ms ease, color 180ms ease;
}

.button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  min-height: 3rem;
  padding: 0.85rem 1.3rem;
  border-radius: 999px;
  font-weight: 700;
  text-decoration: none;
  border: 1px solid transparent;
}

.button:hover,
.button:focus-visible,
.text-link:hover,
.text-link:focus-visible {
  transform: translateY(-1px);
}

.button-primary {
  background: linear-gradient(180deg, var(--accent), var(--accent-deep));
  color: #fff;
  box-shadow: 0 14px 30px rgba(47, 110, 165, 0.22);
}

.button-secondary {
  border-color: rgba(19, 37, 47, 0.12);
  background: rgba(255, 255, 255, 0.62);
  color: var(--text);
}

.button-full {
  width: 100%;
}

.text-link {
  color: var(--accent-deep);
  font-weight: 700;
  text-decoration: none;
}

.section {
  padding: 2rem 0 4rem;
}

.section-tight {
  padding-top: 1rem;
}

.section-heading {
  max-width: 44rem;
  margin-bottom: 1.75rem;
}

.section-heading h2 {
  font-size: clamp(1.8rem, 3vw, 3rem);
  margin-bottom: 0.75rem;
}

.calculator-grid,
.definition-grid,
.content-grid {
  display: grid;
  gap: 1.25rem;
}

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

.content-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

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

.definition-grid-two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.calculator-card,
.definition-card {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.94), rgba(255, 255, 255, 0.78));
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.calculator-card.featured {
  background: linear-gradient(180deg, rgba(47, 110, 165, 0.12), rgba(255, 255, 255, 0.94));
}

.calculator-card h3,
.content-card h2,
.definition-card h3 {
  font-size: 1.35rem;
  margin-bottom: 0.75rem;
}

.calculator-form {
  display: grid;
  gap: 1rem;
  margin-top: 1.25rem;
}

.input-row {
  display: grid;
  gap: 0.9rem;
}

.input-row.split {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.calculator-form label {
  display: grid;
  gap: 0.45rem;
  font-weight: 600;
}

.calculator-form span {
  font-size: 0.95rem;
}

.calculator-form input {
  width: 100%;
  min-height: 3.25rem;
  border-radius: 14px;
  border: 1px solid rgba(19, 37, 47, 0.14);
  background: rgba(255, 255, 255, 0.96);
  padding: 0.85rem 1rem;
  color: var(--text);
  font: inherit;
  transition: border-color 180ms ease, box-shadow 180ms ease, transform 180ms ease;
}

.calculator-form input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(47, 110, 165, 0.16);
}

.result-box {
  padding: 1rem;
  border-radius: var(--radius-md);
  background: rgba(47, 110, 165, 0.08);
}

.result-label {
  margin: 0 0 0.2rem;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.result-value {
  display: block;
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  line-height: 1.1;
  margin-bottom: 0.5rem;
}

.helper-text,
.formula-text {
  margin: 0;
  color: var(--muted);
  font-size: 0.94rem;
}

.formula-text {
  font-weight: 600;
  color: var(--accent-deep);
}

.site-footer {
  padding: 0 0 2rem;
}

.footer-row {
  justify-content: space-between;
  padding: 1rem 0;
  border-top: 1px solid rgba(19, 37, 47, 0.08);
  color: var(--muted);
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  animation: reveal-up 700ms ease forwards;
}

.delay-1 {
  animation-delay: 120ms;
}

.delay-2 {
  animation-delay: 240ms;
}

@keyframes reveal-up {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 1080px) {
  .calculator-grid,
  .definition-grid,
  .definition-grid-two,
  .content-grid {
    grid-template-columns: 1fr;
  }

  .hero-copy h1 {
    max-width: 100%;
  }
}

@media (max-width: 760px) {
  .topbar,
  .site-nav,
  .hero-actions,
  .footer-row {
    flex-direction: column;
    align-items: stretch;
  }

  .site-nav {
    border-radius: 22px;
    width: 100%;
  }

  .nav-link,
  .button {
    text-align: center;
  }

  .nav-link {
    width: 100%;
  }

  .input-row.split {
    grid-template-columns: 1fr;
  }

  .hero {
    padding-top: 1.5rem;
  }

  .hero-copy h1 {
    font-size: 2.35rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-actions .button {
    width: 100%;
  }
}

@media (max-width: 520px) {
  .brand-copy strong {
    font-size: 0.88rem;
  }

  .brand-copy span {
    font-size: 0.8rem;
  }

  .hero-copy,
  .calculator-card,
  .definition-card,
  .content-card {
    padding: 1.2rem;
    border-radius: 22px;
  }

  .hero-copy h1 {
    font-size: 1.95rem;
  }

  .topbar {
    padding: 0.85rem 0;
  }

  .brand {
    width: 100%;
    justify-content: center;
  }

  .brand-copy {
    align-items: center;
    text-align: center;
  }

  .site-nav {
    padding: 0.3rem;
  }

  .nav-link {
    padding: 0.8rem 0.9rem;
  }
}