:root {
  --ink: #13202b;
  --soft: #5d6b76;
  --muted: #82909a;
  --line: rgba(19, 32, 43, 0.13);
  --paper: #ffffff;
  --wash: #f4f7f3;
  --blue: #2368d7;
  --green: #247253;
  --gold: #a8760b;
  --page: min(1120px, calc(100vw - 48px));
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--wash);
  font-family: Inter, "Segoe UI", "Microsoft YaHei", sans-serif;
  line-height: 1.65;
}

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

button,
a {
  font: inherit;
}

button {
  cursor: pointer;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 100;
  padding: 10px 14px;
  color: #fff;
  background: var(--ink);
  transform: translateY(-160%);
}

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

.page-width,
.header-inner {
  width: var(--page);
  margin: 0 auto;
}

.updates-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--line);
  background: rgba(244, 247, 243, 0.94);
  backdrop-filter: blur(16px);
}

.header-inner,
.brand,
.header-actions,
.language-switch,
.back-link,
.brand-signal,
.hero-meta,
.operator-line,
.format-flow,
.color-value,
.release-actions,
.footer-inner,
.footer-inner nav {
  display: flex;
  align-items: center;
}

.header-inner {
  justify-content: space-between;
  min-height: 72px;
}

.brand {
  gap: 11px;
}

.brand img {
  border-radius: 8px;
}

.brand > span {
  display: grid;
  line-height: 1.15;
}

.brand strong {
  font-size: 1rem;
}

.brand small {
  color: var(--soft);
  font-size: 0.78rem;
}

.header-actions {
  gap: 16px;
}

.language-switch {
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper);
}

.language-switch button {
  min-width: 46px;
  min-height: 34px;
  padding: 0 10px;
  border: 0;
  border-radius: 999px;
  color: var(--soft);
  background: transparent;
  font-size: 0.82rem;
}

.language-switch button[aria-pressed="true"] {
  color: #fff;
  background: var(--ink);
}

.back-link {
  gap: 7px;
  color: var(--soft);
  font-size: 0.9rem;
}

.back-link:hover,
.secondary-action:hover,
.footer-inner a:hover {
  color: var(--blue);
}

.updates-hero {
  padding: 72px 0 64px;
  border-bottom: 1px solid var(--line);
  background: var(--paper);
}

.brand-signal {
  gap: 12px;
  margin-bottom: 34px;
  font-size: 1rem;
  font-weight: 750;
}

.brand-signal img {
  border-radius: 8px;
}

.eyebrow,
.section-kicker,
.release-summary > p {
  margin: 0 0 12px;
  color: var(--blue);
  font-size: 0.82rem;
  font-weight: 750;
  letter-spacing: 0;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  max-width: 900px;
  margin-bottom: 20px;
  font-size: 4rem;
  line-height: 1.08;
  letter-spacing: 0;
}

h1 strong {
  color: var(--green);
  font-weight: inherit;
}

.hero-lead {
  max-width: 720px;
  margin-bottom: 34px;
  color: var(--soft);
  font-size: 1.1rem;
}

.hero-meta {
  flex-wrap: wrap;
  gap: 36px;
}

.hero-meta > span {
  display: grid;
  gap: 2px;
}

.hero-meta small {
  color: var(--muted);
  font-size: 0.78rem;
}

.hero-meta b,
.hero-meta time {
  color: var(--ink);
  font-weight: 700;
}

.release-section {
  padding: 78px 0 92px;
}

.release-previous {
  border-top: 1px solid var(--line);
  background: var(--paper);
}

.release-layout {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 72px;
}

.release-summary {
  position: sticky;
  top: 110px;
  align-self: start;
}

.release-summary h2 {
  margin-bottom: 14px;
  font-size: 2rem;
  line-height: 1.1;
  letter-spacing: 0;
}

.release-status {
  display: inline-block;
  margin-bottom: 14px;
  padding: 4px 9px;
  border-radius: 6px;
  color: var(--green);
  background: #e4f1e8;
  font-size: 0.78rem;
  font-weight: 700;
}

.release-status.history {
  color: var(--soft);
  background: #edf0f2;
}

.release-summary time {
  display: block;
  color: var(--muted);
  font-size: 0.85rem;
}

.release-intro {
  max-width: 760px;
  margin-bottom: 44px;
}

.release-intro h2 {
  margin-bottom: 16px;
  font-size: 2.4rem;
  line-height: 1.18;
  letter-spacing: 0;
}

.release-intro > p:last-child {
  color: var(--soft);
  font-size: 1.03rem;
}

.change-list {
  border-top: 1px solid var(--line);
}

.change-row {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 22px;
  padding: 34px 0;
  border-bottom: 1px solid var(--line);
}

.change-index {
  color: var(--blue);
  font-size: 0.82rem;
  font-weight: 800;
}

.change-row h3 {
  margin-bottom: 9px;
  font-size: 1.28rem;
  line-height: 1.35;
  letter-spacing: 0;
}

.change-row p {
  max-width: 760px;
  margin-bottom: 18px;
  color: var(--soft);
}

.formula-change {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
  width: fit-content;
  max-width: 100%;
  padding: 14px 16px;
  border-radius: 6px;
  color: #eaf2ff;
  background: var(--ink);
}

code {
  font-family: Consolas, "SFMono-Regular", monospace;
  letter-spacing: 0;
}

.operator-line {
  gap: 14px;
  min-height: 54px;
  color: var(--ink);
  font-family: "Cambria Math", "Times New Roman", serif;
  font-size: 2rem;
}

.operator-line i {
  width: 1px;
  height: 34px;
  margin: 0 4px;
  background: var(--line);
}

.operator-line .unchanged {
  color: var(--muted);
}

.format-flow {
  flex-wrap: wrap;
  gap: 8px;
}

.format-flow span,
.format-flow b {
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  font-size: 0.82rem;
}

.format-flow span {
  color: var(--green);
  border-color: rgba(36, 114, 83, 0.25);
  background: #eaf4ed;
}

.bidirectional-flow {
  display: grid;
  gap: 8px;
  width: fit-content;
  max-width: 100%;
}

.bidirectional-flow > div {
  display: grid;
  grid-template-columns: minmax(92px, auto) 24px minmax(126px, auto);
  align-items: center;
  gap: 8px;
}

.bidirectional-flow span,
.bidirectional-flow b,
.bidirectional-flow .duolan-target {
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  font-size: 0.82rem;
  text-align: center;
}

.bidirectional-flow b,
.bidirectional-flow .duolan-target {
  color: var(--green);
  border-color: rgba(36, 114, 83, 0.25);
  background: #eaf4ed;
  font-weight: 700;
}

.bidirectional-flow i {
  color: var(--blue);
  font-style: normal;
  text-align: center;
}

.font-setting {
  display: flex;
  align-items: center;
  gap: 11px;
  width: fit-content;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
}

.font-setting span {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 4px;
  color: #fff;
  background: var(--ink);
  font-family: Georgia, serif;
  font-size: 1rem;
}

.font-setting b {
  font-size: 0.84rem;
}

.color-value {
  gap: 10px;
  width: fit-content;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
}

.color-swatch {
  width: 24px;
  height: 24px;
  border: 1px solid rgba(19, 32, 43, 0.16);
  border-radius: 4px;
  background: #c7edcc;
}

.release-actions {
  gap: 18px;
  margin-top: 42px;
}

.primary-action,
.secondary-action {
  min-height: 46px;
  font-weight: 700;
}

.primary-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 0 18px;
  border-radius: 7px;
  color: #fff;
  background: var(--ink);
}

.primary-action:hover {
  background: var(--blue);
}

.secondary-action {
  display: inline-flex;
  align-items: center;
  color: var(--soft);
}

.updates-footer {
  padding: 28px 0 36px;
  border-top: 1px solid var(--line);
  background: var(--paper);
}

.footer-inner {
  justify-content: space-between;
  gap: 24px;
  color: var(--soft);
  font-size: 0.86rem;
}

.footer-inner > div {
  display: grid;
  gap: 3px;
}

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

.footer-inner nav {
  flex-wrap: wrap;
  gap: 20px;
}

@media (max-width: 760px) {
  :root {
    --page: calc(100vw - 28px);
  }

  .header-inner {
    min-height: 66px;
  }

  .brand small,
  .back-link span {
    display: none;
  }

  .header-actions {
    gap: 10px;
  }

  .updates-hero {
    padding: 48px 0 44px;
  }

  .brand-signal {
    margin-bottom: 26px;
  }

  h1 {
    font-size: 2.65rem;
    line-height: 1.12;
  }

  .hero-lead {
    font-size: 1rem;
  }

  .hero-meta {
    gap: 24px;
  }

  .release-section {
    padding: 54px 0 68px;
  }

  .release-layout {
    grid-template-columns: 1fr;
    gap: 38px;
  }

  .release-summary {
    position: static;
    padding-bottom: 28px;
    border-bottom: 1px solid var(--line);
  }

  .release-intro h2 {
    font-size: 2rem;
  }

  .change-row {
    grid-template-columns: 38px minmax(0, 1fr);
    gap: 12px;
    padding: 28px 0;
  }

  .formula-change {
    align-items: flex-start;
    flex-direction: column;
  }

  .formula-change svg {
    transform: rotate(90deg);
  }

  .bidirectional-flow {
    width: 100%;
  }

  .bidirectional-flow > div {
    grid-template-columns: minmax(0, 1fr) 20px minmax(0, 1fr);
  }

  .release-actions,
  .footer-inner {
    align-items: flex-start;
    flex-direction: column;
  }
}

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