:root {
  color-scheme: light;
  --ink: #18212f;
  --muted: #637083;
  --line: #d8dee7;
  --panel: #f7f9fb;
  --accent: #0d7c7a;
  --accent-strong: #095f5e;
  --sun: #f0b429;
  --coral: #df6b57;
  --violet: #5865a7;
  --white: #ffffff;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--white);
  line-height: 1.55;
}

a {
  color: var(--accent-strong);
}

.site-header {
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.96);
  position: sticky;
  top: 0;
  z-index: 5;
}

.header-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 800;
  text-decoration: none;
  white-space: nowrap;
}

.brand-mark {
  width: 28px;
  height: 28px;
  display: inline-block;
  border: 3px solid var(--accent);
  border-radius: 6px;
  box-shadow: inset -8px -8px 0 rgba(13, 124, 122, 0.14);
}

.top-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  flex-wrap: wrap;
  font-size: 14px;
}

.top-nav a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 650;
}

main {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 20px 42px;
}

.hero {
  min-height: 520px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 460px);
  gap: 36px;
  align-items: center;
  padding: 44px 0 28px;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent-strong);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(38px, 7vw, 76px);
  line-height: 1.02;
  letter-spacing: 0;
  max-width: 760px;
}

h2 {
  margin: 0 0 10px;
  font-size: 26px;
  line-height: 1.15;
  letter-spacing: 0;
}

p {
  margin: 0 0 14px;
}

.intro {
  margin-top: 18px;
  max-width: 680px;
  color: var(--muted);
  font-size: 20px;
}

.ratio-visual {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 18px;
  background: linear-gradient(135deg, #f7f9fb, #ffffff);
}

.ratio-frame {
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 2px solid var(--accent);
  border-radius: 8px;
  background:
    linear-gradient(90deg, rgba(13, 124, 122, 0.14) 1px, transparent 1px),
    linear-gradient(rgba(13, 124, 122, 0.14) 1px, transparent 1px),
    linear-gradient(135deg, rgba(240, 180, 41, 0.32), rgba(88, 101, 167, 0.18));
  background-size: 28px 28px, 28px 28px, auto;
  display: grid;
  place-items: center;
  min-height: 180px;
}

.ratio-frame span {
  background: var(--ink);
  color: var(--white);
  border-radius: 6px;
  padding: 8px 12px;
  font-weight: 800;
}

.ratio-visual p {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.tool-panel,
.quick-card,
.size-table-section,
.tips-section,
.reference-section,
.related-section {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--white);
}

.tool-panel {
  padding: 22px;
  box-shadow: 0 14px 38px rgba(24, 33, 47, 0.08);
}

.tool-heading {
  max-width: 760px;
}

.calculator-grid {
  display: grid;
  grid-template-columns: minmax(220px, 1.4fr) repeat(2, minmax(150px, 0.8fr)) minmax(130px, 0.5fr);
  gap: 14px;
  align-items: end;
  margin-top: 18px;
}

label {
  display: grid;
  gap: 7px;
  color: var(--ink);
  font-weight: 750;
}

input,
select {
  width: 100%;
  min-height: 46px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 10px 12px;
  color: var(--ink);
  background: var(--white);
  font: inherit;
}

.checkbox-label {
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 8px;
  min-height: 46px;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
}

.checkbox-label input {
  width: 18px;
  min-height: 18px;
}

.result-bar {
  margin-top: 16px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}

.result-bar > div {
  padding: 14px;
  background: var(--panel);
  border-right: 1px solid var(--line);
}

.result-bar > div:last-child {
  border-right: 0;
}

.result-label {
  display: block;
  color: var(--muted);
  font-size: 13px;
  font-weight: 750;
}

.result-bar strong {
  display: block;
  margin-top: 4px;
  font-size: 22px;
}

.content-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 18px;
  margin-top: 22px;
}

.content-grid article,
.quick-card,
.size-table-section,
.tips-section,
.reference-section,
.related-section {
  padding: 22px;
}

.content-grid article {
  border: 1px solid var(--line);
  border-radius: 8px;
}

.quick-card {
  background: var(--panel);
}

.quick-card ul {
  margin: 0;
  padding-left: 20px;
}

.quick-card li + li {
  margin-top: 10px;
}

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 12px;
}

th,
td {
  border: 1px solid var(--line);
  padding: 12px;
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--panel);
}

.size-table-section,
.tips-section,
.reference-section,
.related-section {
  margin-top: 22px;
}

.tips-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.tips-grid p {
  min-height: 112px;
  padding: 16px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--panel);
}

.reference-section {
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: 22px;
  align-items: center;
}

.reference-section img {
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.related-card {
  min-height: 132px;
  display: block;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  text-decoration: none;
  background: var(--white);
}

.related-card span {
  display: block;
  color: var(--ink);
  font-weight: 800;
  margin-bottom: 8px;
}

.related-card small {
  color: var(--muted);
  line-height: 1.45;
}

.site-footer {
  border-top: 1px solid var(--line);
  padding: 24px 20px 36px;
  color: var(--muted);
  text-align: center;
}

@media (max-width: 860px) {
  .header-inner {
    align-items: flex-start;
    flex-direction: column;
  }

  .top-nav {
    justify-content: flex-start;
  }

  .hero,
  .content-grid,
  .reference-section {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
    padding-top: 30px;
  }

  .calculator-grid,
  .result-bar,
  .tips-grid,
  .related-grid {
    grid-template-columns: 1fr;
  }

  .result-bar > div {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .result-bar > div:last-child {
    border-bottom: 0;
  }
}

@media (max-width: 520px) {
  main {
    padding-left: 14px;
    padding-right: 14px;
  }

  .header-inner {
    padding-left: 14px;
    padding-right: 14px;
  }

  h1 {
    font-size: 40px;
  }

  .intro {
    font-size: 17px;
  }

  .tool-panel,
  .content-grid article,
  .quick-card,
  .size-table-section,
  .tips-section,
  .reference-section,
  .related-section {
    padding: 16px;
  }
}