:root {
  --accent: #4F6BED;
  --accent-strong: #3B55D6;
  --accent-soft: #4F6BED20;
  --bg: #ffffff;
  --bg-alt: #f7f7f8;
  --text: #1d1d1f;
  --text-dim: #6e6e73;
  --border: #e5e5ea;
  --code-bg: #f5f5f7;
  --code-text: #1d1d1f;
  --ok: #1f8a4c;
  --warn: #b7791f;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d0d0f;
    --bg-alt: #15151a;
    --text: #f5f5f7;
    --text-dim: #9a9aa3;
    --border: #2a2a30;
    --code-bg: #16161b;
    --code-text: #e8e8ec;
    --accent: #7B8FFF;
    --accent-strong: #98a8ff;
    --accent-soft: #7B8FFF33;
    --ok: #4fd07f;
    --warn: #e3b341;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Hiragino Sans", "Noto Sans CJK TC", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 880px;
  margin: 0 auto;
  /* Side gutter only. A `padding` shorthand here would out-rank `section` /
     `footer` (class beats element) and silently zero their vertical padding. */
  padding-inline: 24px;
}

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover { text-decoration: underline; }

code {
  font-family: "SF Mono", "JetBrains Mono", Menlo, Monaco, Consolas, monospace;
  font-size: 0.92em;
  background: var(--code-bg);
  color: var(--code-text);
  padding: 0.15em 0.4em;
  border-radius: 4px;
}

pre {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 16px 20px;
  border-radius: 8px;
  overflow-x: auto;
  border: 1px solid var(--border);
  margin: 16px 0;
}

pre code {
  background: none;
  padding: 0;
  font-size: 0.88em;
  line-height: 1.55;
  color: inherit;
}

h1, h2, h3 {
  line-height: 1.25;
  letter-spacing: -0.01em;
}

h2 {
  font-size: 1.8rem;
  margin-top: 0;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.4em;
}

h3 {
  font-size: 1.2rem;
  margin-top: 1.8em;
  margin-bottom: 0.4em;
}

/* Language switch: the page carries both languages; only the chosen one shows.
   <html data-lang="en"> ships in the markup, so without JS the page is English. */
html[data-lang="en"] body [lang="zh-Hant"],
html[data-lang="zh"] body [lang="en"] {
  display: none !important;
}

[hidden] { display: none !important; }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.dim { color: var(--text-dim); font-weight: normal; }

/* Anchor jumps: smooth, and clear of the sticky top bar. */
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}
section[id], header[id] { scroll-margin-top: 64px; }

/* Table of contents.
   Narrow screens: a horizontal, scrollable row under the top bar.
   Wide screens (≥ 1320px, where the left gutter can hold it without
   covering the 880px content column): a fixed sidebar on the left. */
.toc {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  overflow-x: auto;
  padding-inline: 24px;
}
.toc-title { display: none; }
.toc ol {
  list-style: none;
  margin: 0 auto;
  padding: 8px 0;
  max-width: 832px;
  display: flex;
  gap: 4px 18px;
  white-space: nowrap;
}
.toc a {
  display: block;
  font-size: 0.88rem;
  color: var(--text-dim);
  padding: 2px 0;
  border-radius: 4px;
}
.toc a:hover { color: var(--text); text-decoration: none; }
.toc a[aria-current="true"] { color: var(--accent); font-weight: 600; }
.toc a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

@media (min-width: 1320px) {
  .toc {
    position: fixed;
    top: calc(env(safe-area-inset-top, 0px) + 84px);
    left: calc((100vw - 880px) / 2 - 204px);
    width: 180px;
    padding: 0;
    border-bottom: 0;
    background: transparent;
    overflow: visible;
    z-index: 5;
  }
  .toc-title {
    display: block;
    margin: 0 0 8px;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--text-dim);
  }
  .toc ol {
    flex-direction: column;
    gap: 2px;
    padding: 0;
    white-space: normal;
    border-left: 1px solid var(--border);
  }
  .toc a {
    padding: 4px 0 4px 12px;
    margin-left: -1px;
    border-left: 2px solid transparent;
    border-radius: 0;
  }
  .toc a[aria-current="true"] { border-left-color: var(--accent); }
}

/* Top bar */
.topbar {
  position: sticky;
  top: env(safe-area-inset-top, 0px);
  z-index: 10;
  background: var(--bg);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding-block: 10px;
}
.topbar-brand {
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.01em;
}
.topbar-brand:hover { text-decoration: none; color: var(--accent); }

.lang-switch {
  display: inline-flex;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 2px;
  background: var(--bg-alt);
}
.lang-switch button {
  font: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-dim);
  background: transparent;
  border: 0;
  border-radius: 999px;
  padding: 4px 12px;
  cursor: pointer;
}
.lang-switch button[aria-pressed="true"] {
  background: var(--accent);
  color: #fff;
}
.lang-switch button:focus-visible,
.release-picker select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.note {
  background: var(--accent-soft);
  border-left: 3px solid var(--accent);
  padding: 12px 16px;
  border-radius: 6px;
  margin: 12px 0;
}
.note.warn {
  background: color-mix(in srgb, var(--warn) 14%, transparent);
  border-left-color: var(--warn);
}

/* Hero */
.hero {
  background: var(--bg-alt);
  border-bottom: 1px solid var(--border);
  padding: 60px 0 48px;
  text-align: center;
}

.hero-mark {
  display: inline-grid;
  place-items: center;
  width: 96px;
  height: 96px;
  border-radius: 22px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-strong) 100%);
  color: #fff;
  font-family: "SF Mono", "JetBrains Mono", Menlo, monospace;
  font-weight: 700;
  font-size: 1.6rem;
  letter-spacing: -0.04em;
  box-shadow: 0 6px 24px rgba(0,0,0,0.12);
}

.hero h1 {
  font-size: 2.6rem;
  margin: 18px 0 4px;
  letter-spacing: -0.02em;
}

.tagline {
  font-size: 1.15rem;
  margin: 8px 0 4px;
  font-weight: 500;
}

.subtagline {
  color: var(--text-dim);
  margin: 0 0 24px;
  font-size: 0.95rem;
}

.badges {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
  margin: 20px 0 28px;
}
.badges img { vertical-align: middle; }

.cta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-top: 8px;
}

.btn {
  display: inline-block;
  padding: 10px 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-weight: 500;
  font-size: 0.95rem;
  transition: background 0.15s, border-color 0.15s;
}
.btn:hover {
  background: var(--bg);
  text-decoration: none;
  border-color: var(--text-dim);
}
.btn.primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn.primary:hover {
  background: var(--accent-strong);
  border-color: var(--accent-strong);
}

/* Sections */
section {
  padding: 56px 0;
  border-bottom: 1px solid var(--border);
}
section:last-of-type { border-bottom: none; }

/* Features grid */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin-top: 24px;
}

.feature {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
}
.feature h3 {
  margin: 0 0 6px;
  font-size: 1.05rem;
  color: var(--accent);
}
.feature p { margin: 6px 0; font-size: 0.93rem; }

/* Event-sourcing flow: numbered steps */
.steps {
  list-style: none;
  counter-reset: step;
  padding: 0;
  margin: 24px 0 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
}
.steps li {
  counter-increment: step;
  position: relative;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px 14px 52px;
}
.steps li::before {
  content: counter(step);
  position: absolute;
  left: 14px;
  top: 14px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font: 700 0.8rem/26px "SF Mono", Menlo, monospace;
  text-align: center;
}
.steps li strong { display: block; font-size: 0.95rem; margin-bottom: 2px; }
.steps li p { margin: 0; font-size: 0.88rem; color: var(--text-dim); }

/* Module table */
.table-scroll { overflow-x: auto; }
table.compat {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: 0.95rem;
}
table.compat th,
table.compat td {
  text-align: left;
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
table.compat thead {
  background: var(--bg-alt);
}
table.compat th {
  font-weight: 600;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-dim);
}
table.compat td:first-child { white-space: nowrap; }
.group-row td {
  background: var(--bg-alt);
  font-weight: 600;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-dim);
}

/* API grid */
.api-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 18px;
  margin-top: 24px;
}

.api-card {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
}
.api-card h3 {
  margin: 0 0 8px;
  font-size: 1rem;
  color: var(--accent);
}
.api-card p { margin: 0 0 10px; font-size: 0.9rem; color: var(--text-dim); }
.api-card pre {
  margin: 0;
  font-size: 0.85em;
}

/* Footer */
footer {
  padding: 40px 0 32px;
  text-align: center;
  color: var(--text-dim);
}
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  justify-content: center;
  margin-bottom: 16px;
}
.footer-links a { font-size: 0.95rem; }
.footer-meta {
  margin: 0;
  font-size: 0.88rem;
}

/* What's new */
.whats-new {
  background: linear-gradient(135deg, var(--accent-soft) 0%, transparent 70%);
  border-radius: 16px;
  padding: 36px 28px 44px;
  margin: 32px auto;
  border: 1px solid var(--border);
}

.whats-new-tag {
  display: inline-block;
  padding: 4px 12px;
  background: var(--accent);
  color: #fff;
  border-radius: 100px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 10px;
}
.whats-new-tag.beta { background: var(--warn); color: #1d1d1f; }
.whats-new-tag.breaking { background: #c0392b; }

.whats-new h2 {
  border-bottom: none;
  padding-bottom: 0;
  margin: 0;
  font-size: 2rem;
}

/* Release picker: "What's new in [ 1.4 (pre-release) ▾ ]" */
.release-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 14px;
  margin-bottom: 28px;
}
.release-picker { display: none; }
html.js .release-picker { display: block; }
.release-picker select {
  font: inherit;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--bg);
  border: 1px solid var(--accent);
  border-radius: 10px;
  padding: 6px 36px 6px 14px;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--accent) 50%),
                    linear-gradient(135deg, var(--accent) 50%, transparent 50%);
  background-position: calc(100% - 18px) 55%, calc(100% - 12px) 55%;
  background-size: 6px 6px, 6px 6px;
  background-repeat: no-repeat;
}

/* Without JS every release is shown; separate them. */
.release + .release {
  margin-top: 40px;
  padding-top: 32px;
  border-top: 1px solid var(--border);
}
html.js .release + .release { margin-top: 0; padding-top: 0; border-top: 0; }

.release-title {
  font-size: 1.5rem;
  margin: 4px 0 8px;
}
.release-link {
  margin: 24px 0 0;
  font-weight: 600;
}
.release-link + .release-link { margin-top: 6px; }

.lead {
  font-size: 1.05rem;
  margin: 12px 0;
  max-width: 760px;
}

.highlights {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin: 28px 0 36px;
}

.highlight {
  padding: 18px 20px;
  border-radius: 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  transition: transform 0.15s, box-shadow 0.15s;
}
.highlight:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.06);
}
.highlight h3 {
  margin: 0 0 8px;
  font-size: 1.02rem;
  color: var(--text);
}
.highlight h3 .since {
  display: inline-block;
  margin-left: 6px;
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 2px 8px;
  vertical-align: middle;
}
.highlight p {
  margin: 6px 0;
  font-size: 0.92rem;
}
.highlight pre {
  margin: 10px 0 0;
  font-size: 0.8em;
}

.compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 16px 0 24px;
}
.compare-col h5 {
  margin: 0 0 8px;
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
}
.compare-old h5::before {
  content: "↩ ";
  color: var(--text-dim);
}
.compare-new h5 {
  color: var(--accent);
}
.compare-new h5::before {
  content: "→ ";
}
.compare-col pre {
  margin: 0;
  font-size: 0.82em;
  height: 100%;
}
.compare-new pre {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent-soft);
}

.subsection-title {
  margin: 32px 0 10px;
  font-size: 1.15rem;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 18px;
  margin-top: 8px;
}
.cta-note {
  color: var(--text-dim);
  font-size: 0.88rem;
  flex: 1;
  min-width: 220px;
}

/* Rename table inside a release */
table.rename td code { white-space: nowrap; }
table.rename td.old { color: #c0392b; }
table.rename td.new { color: var(--ok); }

/* Docs cards */
.doc-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin-top: 24px;
}
.doc-card {
  display: block;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  color: var(--text);
}
.doc-card:hover { border-color: var(--accent); text-decoration: none; }
.doc-card h3 { margin: 0 0 6px; font-size: 1.02rem; color: var(--accent); }
.doc-card p { margin: 0; font-size: 0.9rem; color: var(--text-dim); }

@media (max-width: 720px) {
  .compare { grid-template-columns: 1fr; }
}

/* Mobile */
@media (max-width: 600px) {
  .hero { padding: 40px 0 32px; }
  .hero h1 { font-size: 2rem; }
  .tagline { font-size: 1rem; }
  h2 { font-size: 1.5rem; }
  section { padding: 40px 0; }
  pre { padding: 12px 14px; font-size: 0.85em; }
  .whats-new { padding: 28px 20px 32px; margin: 20px 12px; }
  .whats-new h2 { font-size: 1.6rem; }
}