:root {
  color-scheme: dark;
  --background: #030316;
  --surface: #121321;
  --surface-soft: #181a2a;
  --border: #292c42;
  --text: #f5f6ff;
  --muted: #b8bbcc;
  --accent: #9aabff;
  --success: #71d8bb;
  --content-width: 1080px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--background);
}

body {
  margin: 0;
  min-width: 280px;
  overflow-x: hidden;
  background: var(--background);
  color: var(--text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-underline-offset: 0.2em;
}

a:hover {
  color: #c7d0ff;
}

a:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
  border-radius: 5px;
}

.skip-link {
  position: fixed;
  z-index: 9999;
  top: 12px;
  left: 12px;
  transform: translateY(-180%);
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--text);
  color: #090a12;
  font-weight: 750;
}

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

#calculator-app {
  position: relative;
  width: 100%;
  height: 100vh;
  height: 100dvh;
  min-height: 360px;
  max-height: 980px;
  overflow: hidden;
  background: #000014;
  isolation: isolate;
}

.app-loading,
.app-error {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  justify-items: center;
  gap: 12px;
  padding: 28px;
  color: var(--muted);
  text-align: center;
}

.app-loading img {
  border-radius: 16px;
}

#calculator-app.is-ready .app-loading {
  display: none;
}

.seo-content,
.footer-inner {
  width: min(calc(100% - 40px), var(--content-width));
  margin-inline: auto;
}

.seo-content {
  padding-block: 76px 88px;
}

.seo-hero {
  max-width: 850px;
  padding-bottom: 52px;
}

.eyebrow,
.feature-label {
  margin: 0 0 10px;
  color: var(--success);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  line-height: 1.2;
  letter-spacing: -0.025em;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 6vw, 4rem);
}

h2 {
  margin: 0 0 24px;
  font-size: clamp(1.55rem, 3.5vw, 2.35rem);
}

h3 {
  margin: 0 0 10px;
  font-size: 1.22rem;
}

p,
ul {
  margin-top: 0;
}

.lede {
  max-width: 780px;
  margin: 20px 0 0;
  color: var(--muted);
  font-size: clamp(1.03rem, 2vw, 1.17rem);
}

.category-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 28px;
}

.category-links a {
  padding: 8px 13px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text);
  font-size: 0.9rem;
  font-weight: 700;
  text-decoration: none;
}

.category-links a:hover {
  border-color: #525978;
  background: var(--surface-soft);
}

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

.feature-card {
  scroll-margin-top: 20px;
  padding: 26px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--surface);
}

.feature-card p:last-child {
  margin-bottom: 0;
  color: var(--muted);
}

.disclaimer {
  max-width: 860px;
  margin: 20px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.how-to {
  margin-top: 80px;
}

.how-to-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 32px 48px;
}

.how-to-grid article {
  padding-top: 18px;
  border-top: 1px solid var(--border);
}

.how-to-grid p {
  margin-bottom: 0;
  color: var(--muted);
}

.benefits {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: 48px;
  margin-top: 80px;
  padding-block: 54px;
  border-block: 1px solid var(--border);
}

.benefits h2 {
  margin-bottom: 0;
}

.benefits ul {
  margin-bottom: 0;
  padding-left: 1.2rem;
  color: var(--muted);
}

.benefits li + li {
  margin-top: 12px;
}

.faq {
  scroll-margin-top: 20px;
  padding-top: 80px;
}

.faq-grid {
  display: grid;
  gap: 12px;
}

details {
  padding: 0 20px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface);
}

summary {
  padding-block: 18px;
  cursor: pointer;
  font-weight: 750;
}

details p {
  max-width: 860px;
  margin-bottom: 20px;
  color: var(--muted);
}

.english-summary {
  margin-top: 72px;
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--surface-soft);
}

.english-summary h2 {
  margin-bottom: 12px;
  font-size: clamp(1.35rem, 3vw, 1.8rem);
}

.english-summary p:last-child {
  max-width: 850px;
  margin-bottom: 0;
  color: var(--muted);
}

.site-footer {
  border-top: 1px solid var(--border);
  background: #080918;
}

.footer-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(260px, auto) auto;
  align-items: center;
  gap: 32px;
  min-height: 160px;
  padding-block: 30px;
  color: var(--muted);
  font-size: 0.9rem;
}

.footer-inner strong {
  color: var(--text);
}

.footer-inner p {
  margin: 5px 0 0;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px 16px;
}

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

.copyright {
  white-space: nowrap;
}

@media (min-width: 1100px) and (min-height: 900px) {
  #calculator-app {
    border-bottom: 1px solid var(--border);
  }
}

@media (max-width: 760px) {
  #calculator-app {
    max-height: none;
  }

  .seo-content {
    padding-block: 56px 68px;
  }

  .seo-hero {
    padding-bottom: 38px;
  }

  .feature-grid,
  .how-to-grid,
  .benefits {
    grid-template-columns: 1fr;
  }

  .benefits {
    gap: 18px;
    margin-top: 58px;
    padding-block: 42px;
  }

  .how-to {
    margin-top: 58px;
  }

  .faq {
    padding-top: 58px;
  }

  .english-summary {
    margin-top: 56px;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .footer-links {
    justify-content: flex-start;
  }
}

@media (max-width: 420px) {
  .seo-content,
  .footer-inner {
    width: min(calc(100% - 28px), var(--content-width));
  }

  .seo-content {
    padding-top: 46px;
  }

  .feature-card,
  .english-summary {
    padding: 20px;
  }

  details {
    padding-inline: 16px;
  }
}

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