:root {
  color-scheme: light;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  --ink: #242b30;
  --muted: #647078;
  --line: #dbe0e1;
  --paper: #ffffff;
  --wash: #f5f7f7;
  --accent: #b94338;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--paper); color: var(--ink); }
a { color: inherit; }
button, input { font: inherit; }
button, a, input { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
::selection { background: #f6d9d5; }
.shell { width: min(100% - 48px, 1120px); 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: absolute; z-index: 10; top: -60px; left: 16px; background: var(--ink); color: white; padding: 10px 14px; text-decoration: none; }
.skip-link:focus { top: 10px; }

.site-header { border-bottom: 1px solid var(--line); }
.header-inner { min-height: 70px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; font-size: 16px; font-weight: 700; letter-spacing: .02em; white-space: nowrap; }
.brand-mark { display: grid; place-items: center; width: 30px; height: 30px; background: var(--ink); color: #fff; font-size: 26px; line-height: 1; font-weight: 400; border-radius: 4px; }
nav { display: flex; align-items: center; gap: 30px; }
nav a { text-decoration: none; color: var(--muted); font-size: 13px; font-weight: 600; }
nav a:hover, nav a:focus-visible { color: var(--ink); }

.intro { display: grid; grid-template-columns: minmax(0, 1fr) minmax(275px, 350px); align-items: end; gap: 48px; padding: 78px 0 70px; border-bottom: 1px solid var(--line); }
.eyebrow { margin: 0 0 17px; font-size: 11px; font-weight: 800; letter-spacing: .16em; color: var(--accent); }
h1, h2, p { margin-top: 0; }
h1 { margin-bottom: 12px; font-size: clamp(42px, 6vw, 74px); line-height: 1.1; letter-spacing: -.055em; font-weight: 750; }
.lead { margin-bottom: 0; color: var(--muted); font-size: 15px; }
.utc-now { min-height: 143px; border-left: 2px solid var(--accent); padding: 4px 0 4px 24px; display: flex; flex-direction: column; justify-content: center; }
.data-label { font-size: 12px; color: var(--muted); font-weight: 650; letter-spacing: .02em; }
.utc-digits, .clock-digits { display: block; font-variant-numeric: tabular-nums; letter-spacing: -.035em; line-height: 1.1; }
.utc-digits { margin: 10px 0 8px; font-size: clamp(36px, 4vw, 49px); font-weight: 700; }
.data-detail { color: var(--muted); font-size: 12px; }

.section { padding: 45px 0 54px; border-bottom: 1px solid var(--line); scroll-margin-top: 24px; }
.section-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 20px; margin-bottom: 27px; }
h2 { margin-bottom: 0; font-size: 21px; font-weight: 700; letter-spacing: -.025em; }
.section-note { color: var(--muted); font-size: 12px; white-space: nowrap; }
.clock-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); }
.clock-item { padding: 7px 24px 5px; border-left: 1px solid var(--line); display: flex; flex-direction: column; min-width: 0; }
.clock-item:first-child { padding-left: 0; border-left: 0; }
.clock-digits { margin: 13px 0 9px; font-size: clamp(25px, 3vw, 34px); font-weight: 650; white-space: nowrap; }

.converter { padding-bottom: 75px; border: 0; }
.converter-form { display: flex; align-items: end; flex-wrap: wrap; gap: 14px; padding: 24px; background: var(--wash); border: 1px solid var(--line); }
.field { display: flex; flex-direction: column; gap: 8px; min-width: 0; }
.field label { font-size: 12px; font-weight: 650; }
.field input { height: 42px; padding: 0 11px; border: 1px solid #bfc8cb; border-radius: 3px; background: var(--paper); color: var(--ink); font-size: 14px; }
.field input:hover { border-color: var(--muted); }
.field input:focus-visible { border-color: var(--accent); }
.field:first-child input { min-width: 170px; }
.field:nth-child(2) input { min-width: 145px; }
button { height: 42px; padding: 0 23px; border: 1px solid var(--ink); border-radius: 3px; background: var(--ink); color: white; cursor: pointer; font-size: 13px; font-weight: 700; }
button:hover { background: #3c464b; }
button:active { transform: translateY(1px); }
.form-status { min-height: 22px; margin: 11px 0 3px; color: var(--muted); font-size: 12px; }
.table-scroll { overflow-x: auto; }
table { width: 100%; min-width: 600px; border-collapse: collapse; text-align: left; font-variant-numeric: tabular-nums; }
th, td { padding: 15px 14px; border-bottom: 1px solid var(--line); font-size: 13px; }
th:first-child, td:first-child { padding-left: 0; }
th:last-child, td:last-child { padding-right: 0; text-align: right; }
th { color: var(--muted); font-size: 11px; font-weight: 700; white-space: nowrap; }
td:first-child { font-weight: 650; }
td:nth-child(3) { font-size: 16px; font-weight: 700; }
.zone-id { display: block; margin-top: 3px; color: var(--muted); font-size: 11px; font-weight: 400; }
.empty-cell { color: var(--muted); text-align: center !important; padding: 28px 0; font-weight: 400 !important; }
.noscript { margin-top: -35px; margin-bottom: 35px; padding: 12px; background: var(--wash); color: var(--muted); font-size: 13px; }

.site-footer { border-top: 1px solid var(--line); }
.footer-inner { min-height: 74px; display: flex; align-items: center; gap: 28px; color: var(--muted); font-size: 11px; }
.error-page { min-height: 100vh; display: flex; flex-direction: column; }
.error-main { flex: 1; padding-block: clamp(80px, 14vh, 160px); }
.error-main h1 { font-size: clamp(42px, 6vw, 70px); }
.error-main > p:not(.eyebrow) { color: var(--muted); font-size: 15px; }
.home-link { display: inline-flex; align-items: center; gap: 17px; margin-top: 25px; padding: 12px 0; border-bottom: 2px solid var(--accent); text-decoration: none; font-size: 14px; font-weight: 700; }
.home-link:hover { color: var(--accent); }

@media (max-width: 760px) {
  .intro { grid-template-columns: 1fr; gap: 30px; padding: 55px 0 52px; }
  .utc-now { min-height: 0; }
  .clock-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); row-gap: 32px; }
  .clock-item:nth-child(3) { padding-left: 0; border-left: 0; }
}

@media (max-width: 520px) {
  .shell { width: min(100% - 32px, 1120px); }
  .header-inner { min-height: 62px; }
  .brand { font-size: 14px; }
  nav { gap: 12px; }
  nav a { font-size: 11px; }
  .intro { padding-top: 45px; }
  .section { padding: 38px 0 45px; }
  .section-heading { margin-bottom: 24px; }
  .section-note { font-size: 11px; }
  .clock-item { padding-right: 8px; padding-left: 15px; }
  .clock-digits { font-size: clamp(25px, 7vw, 33px); }
  .converter-form { padding: 18px; }
  .field { flex: 1 1 100%; }
  .field input, .field:first-child input, .field:nth-child(2) input { width: 100%; min-width: 0; }
  button { width: 100%; }
  table { min-width: 0; }
  thead { display: none; }
  tbody { display: block; }
  tbody tr { display: grid; grid-template-columns: minmax(0, 1fr) auto; column-gap: 12px; padding: 14px 0; border-bottom: 1px solid var(--line); }
  tbody td { display: block; padding: 0 !important; border: 0; }
  tbody td:first-child { grid-column: 1; grid-row: 1; }
  tbody td:nth-child(2) { grid-column: 1; grid-row: 2; margin-top: 5px; color: var(--muted); font-size: 11px; }
  tbody td:nth-child(3) { grid-column: 2; grid-row: 1; text-align: right; }
  tbody td:nth-child(4) { grid-column: 2; grid-row: 2; margin-top: 5px; color: var(--muted); font-size: 11px; text-align: right; }
  .footer-inner { align-items: start; justify-content: center; flex-direction: column; gap: 3px; padding-block: 15px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  button:active { transform: none; }
}