/* ==========================================================================
   BEPLAY 主页 · 共享样式表  /assets/site.css
   坐标仪表盘 × 出版说明牌 · 冷底暖点
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body,
h1, h2, h3, h4, h5, p, ul, ol, li, figure, figcaption, blockquote, dl, dd {
  margin: 0;
  padding: 0;
}

ul, ol { list-style: none; }

img, svg, video { display: block; max-width: 100%; }

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

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  cursor: pointer;
}

table { border-collapse: collapse; width: 100%; }

/* ---------- 2. 变量 ---------- */
:root {
  --blue: #0B5FFF;
  --blue-deep: #073BB0;
  --blue-pale: #DCE8FF;
  --orange: #FF6A2B;
  --orange-pale: #FFE6DA;
  --ink: #0E1626;
  --ink-2: #0A1120;
  --graphite: #3A465C;
  --mist: #F4F6FA;
  --paper: #FBF6EE;
  --brown: #2A2118;
  --green: #12A87A;
  --line: #E3E7F0;

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", "Noto Sans SC", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: "SFMono-Regular", "JetBrains Mono", "Cascadia Mono", Consolas, "Liberation Mono", "Courier New", monospace;

  --maxw: 1200px;
  --gutter: clamp(16px, 4vw, 40px);
  --r-lg: 26px;
  --r-md: 18px;
  --r-sm: 12px;
  --pill: 999px;
  --ease: cubic-bezier(.22, .61, .36, 1);
  --shadow-card: 0 26px 60px -48px rgba(14, 22, 38, .65);
}

/* ---------- 3. 中文排版基础 ---------- */
body {
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.85;
  color: var(--ink);
  background-color: var(--mist);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: -0.01em;
}

strong { font-weight: 700; }

.mono {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

::selection {
  background: var(--blue);
  color: #fff;
}

:where(a, button, [tabindex]):focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 3px;
  border-radius: 6px;
}

/* ---------- 4. 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: 50%;
  top: 0;
  z-index: 200;
  transform: translate(-50%, -160%);
  padding: 10px 22px;
  border-radius: 0 0 var(--r-sm) var(--r-sm);
  background: var(--orange);
  color: #1B0A02;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.06em;
  transition: transform .2s var(--ease);
}

.skip-link:focus {
  transform: translate(-50%, 0);
}

/* ---------- 5. 刊头 ---------- */
.masthead {
  position: relative;
  background: var(--ink);
  color: var(--mist);
  border-bottom: 1px solid rgba(11, 95, 255, .38);
}

.masthead::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(11, 95, 255, .17) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(11, 95, 255, .13) 1px, transparent 1px);
  background-size: 64px 64px;
  background-position: 50% 0;
  -webkit-mask-image: radial-gradient(130% 88% at 50% 0%, #000 18%, transparent 88%);
  mask-image: radial-gradient(130% 88% at 50% 0%, #000 18%, transparent 88%);
}

.masthead__inner {
  position: relative;
  z-index: 1;
  max-width: var(--maxw);
  margin-inline: auto;
  padding: 26px var(--gutter) 0;
}

.masthead__top {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 20px;
  padding-bottom: 22px;
  border-bottom: 1px solid rgba(220, 232, 255, .1);
}

.masthead__tagline {
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: rgba(220, 232, 255, .58);
}

.masthead__tagline-dot {
  flex: none;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--orange);
  animation: pulse-dot 3s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { box-shadow: 0 0 0 0 rgba(255, 106, 43, .55); opacity: 1; }
  50% { box-shadow: 0 0 0 8px rgba(255, 106, 43, 0); opacity: .6; }
}

.masthead__brand {
  display: block;
  text-align: center;
}

.masthead__brand-name {
  display: block;
  font-size: clamp(28px, 4.6vw, 48px);
  font-weight: 800;
  line-height: 1.04;
  letter-spacing: -0.02em;
  color: #FFFFFF;
}

.masthead__brand-line {
  display: block;
  margin-top: 9px;
  font-size: 11px;
  letter-spacing: 0.34em;
  color: rgba(220, 232, 255, .55);
}

.masthead__meta {
  position: relative;
  justify-self: end;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 9px;
  text-align: right;
}

.version-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 15px;
  border-radius: var(--pill);
  border: 1px solid rgba(255, 106, 43, .45);
  background: rgba(255, 106, 43, .13);
  color: var(--orange-pale);
  font-size: 12px;
  letter-spacing: 0.06em;
  transition: background .2s var(--ease), border-color .2s var(--ease);
}

.version-chip:hover,
.version-chip[aria-expanded="true"] {
  background: rgba(255, 106, 43, .24);
  border-color: var(--orange);
}

.version-chip__dot {
  flex: none;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--orange);
  animation: pulse-dot 3s ease-in-out infinite;
}

.masthead__stamp {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: rgba(220, 232, 255, .45);
}

.masthead__stamp time { color: var(--blue-pale); }

.version-sheet {
  display: none;
  position: absolute;
  top: calc(100% + 12px);
  right: 0;
  z-index: 60;
  width: min(300px, 78vw);
  padding: 16px 18px;
  border: 1px solid rgba(42, 33, 24, .22);
  border-radius: var(--r-md);
  background: var(--paper);
  color: var(--brown);
  text-align: left;
  box-shadow: 0 22px 46px -20px rgba(14, 22, 38, .6);
}

.version-sheet[data-open] { display: block; }

.version-sheet__title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.24em;
  color: var(--brown);
  padding-bottom: 10px;
  margin-bottom: 10px;
  border-bottom: 1px dashed rgba(42, 33, 24, .28);
}

.version-sheet__list {
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.version-sheet__list li {
  position: relative;
  padding-left: 16px;
  font-size: 13px;
  line-height: 1.7;
  color: #4A3B2C;
}

.version-sheet__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 7px;
  height: 1px;
  background: var(--orange);
}

/* ---------- 6. 导航 ---------- */
.nav-row {
  position: relative;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 14px;
  padding: 14px 0 20px;
}

.nav-toggle {
  grid-column: 1;
  justify-self: start;
  display: none;
  align-items: center;
  gap: 10px;
  padding: 9px 16px 9px 13px;
  border-radius: var(--pill);
  border: 1px solid rgba(220, 232, 255, .24);
  color: var(--blue-pale);
  font-size: 13px;
  letter-spacing: 0.12em;
  transition: border-color .2s var(--ease), background .2s var(--ease);
}

.nav-toggle:hover { border-color: var(--blue); background: rgba(11, 95, 255, .18); }

.nav-toggle__bars {
  display: flex;
  flex-direction: column;
  gap: 4px;
  width: 16px;
}

.nav-toggle__bars span {
  display: block;
  height: 1.5px;
  border-radius: 2px;
  background: currentColor;
  transition: transform .22s var(--ease), opacity .22s var(--ease);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }

.nav-list {
  grid-column: 2;
  justify-self: center;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 2px;
  counter-reset: navidx;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  padding: 9px 16px;
  border-radius: var(--pill);
  font-size: 14px;
  letter-spacing: 0.02em;
  color: rgba(220, 232, 255, .76);
  transition: background .2s var(--ease), color .2s var(--ease);
}

.nav-link::before {
  counter-increment: navidx;
  content: counter(navidx, decimal-leading-zero);
  margin-right: 9px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--blue);
  opacity: .85;
}

.nav-link:hover {
  background: rgba(255, 255, 255, .08);
  color: #FFFFFF;
}

.nav-link[aria-current="page"] {
  background: var(--blue);
  color: #FFFFFF;
}

.nav-link[aria-current="page"]::before { color: var(--blue-pale); }

.nav-cta {
  grid-column: 3;
  justify-self: end;
  display: inline-flex;
  align-items: center;
  padding: 10px 21px;
  border-radius: var(--pill);
  background: var(--orange);
  color: #22100A;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.05em;
  box-shadow: 0 12px 26px -14px rgba(255, 106, 43, .95);
  transition: transform .18s var(--ease), background .18s var(--ease);
}

.nav-cta:hover { transform: translateY(-2px); background: #FF7F4A; }

/* ---------- 7. 页脚 ---------- */
.site-foot {
  position: relative;
  margin-top: clamp(56px, 9vw, 108px);
  background: var(--ink-2);
  color: rgba(220, 232, 255, .7);
  border-top: 1px solid rgba(11, 95, 255, .4);
}

.site-foot::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: linear-gradient(to right, rgba(11, 95, 255, .12) 1px, transparent 1px);
  background-size: 64px 100%;
  opacity: .8;
}

.site-foot__inner {
  position: relative;
  z-index: 1;
  max-width: var(--maxw);
  margin-inline: auto;
  padding: clamp(34px, 5vw, 54px) var(--gutter) 0;
}

.site-foot__masthead {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 10px 18px;
  padding-bottom: 22px;
  border-bottom: 1px solid rgba(220, 232, 255, .12);
}

.site-foot__brand {
  font-size: 20px;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: #FFFFFF;
}

.site-foot__brand-line {
  font-size: 11px;
  letter-spacing: 0.3em;
  color: rgba(220, 232, 255, .42);
}

.site-foot__rev {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--blue-pale);
}

.foot-band {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0;
  padding: clamp(26px, 3.6vw, 40px) 0;
}

.foot-col {
  padding: 0 22px;
  border-left: 1px dashed rgba(227, 231, 240, .18);
}

.foot-col:first-child { padding-left: 0; border-left: 0; }
.foot-col:last-child { padding-right: 0; }

.foot-col__heading {
  position: relative;
  margin-bottom: 16px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.24em;
  color: var(--blue-pale);
}

.foot-col__heading::before {
  content: "";
  display: block;
  width: 20px;
  height: 2px;
  margin-bottom: 11px;
  border-radius: 2px;
  background: var(--blue);
}

.foot-list {
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.foot-list--stack { gap: 13px; }

.foot-link {
  display: inline-block;
  width: fit-content;
  font-size: 13.5px;
  color: rgba(220, 232, 255, .72);
  border-bottom: 1px solid transparent;
  transition: color .18s var(--ease), border-color .18s var(--ease);
}

.foot-link:hover {
  color: #FFFFFF;
  border-bottom-color: var(--orange);
}

.foot-item {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.foot-item__key {
  font-size: 10px;
  letter-spacing: 0.22em;
  color: rgba(220, 232, 255, .4);
}

.foot-item__val {
  font-size: 13px;
  line-height: 1.7;
  color: rgba(220, 232, 255, .62);
}

.copy-btn {
  display: inline-flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  width: fit-content;
  padding-bottom: 2px;
  border-bottom: 1px dashed rgba(220, 232, 255, .3);
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.02em;
  color: rgba(220, 232, 255, .82);
  overflow-wrap: anywhere;
  text-align: left;
  transition: color .18s var(--ease), border-color .18s var(--ease);
}

.copy-btn:hover {
  color: var(--blue-pale);
  border-bottom-color: var(--blue);
}

.copy-btn__flag {
  font-family: var(--font-sans);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--green);
  opacity: 0;
  transition: opacity .2s var(--ease);
}

.copy-btn[data-copied] .copy-btn__flag { opacity: 1; }

.foot-icp {
  margin-top: 16px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: rgba(220, 232, 255, .42);
}

.foot-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 26px;
  padding: 18px 0 26px;
  border-top: 1px solid rgba(220, 232, 255, .12);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: rgba(220, 232, 255, .42);
}

.foot-base__addr { max-width: 62ch; }

/* ---------- 8. 布局与容器 ---------- */
.shell {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding: clamp(40px, 6vw, 76px) 0; }

.stack-sm > * + * { margin-top: 12px; }
.stack-md > * + * { margin-top: 20px; }
.stack-lg > * + * { margin-top: 34px; }

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(18px, 2.6vw, 32px);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(16px, 2.2vw, 26px);
}

/* ---------- 9. 坐标轴导览 ---------- */
.coord-axis {
  position: sticky;
  top: 28px;
  display: flex;
  flex-direction: column;
  gap: 22px;
  padding-left: 22px;
  border-left: 1px solid var(--line);
}

.coord-axis__tick {
  position: relative;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--graphite);
  transition: color .2s var(--ease);
}

.coord-axis__tick::before {
  content: "";
  position: absolute;
  left: -22px;
  top: 50%;
  width: 11px;
  height: 1px;
  background: var(--line);
  transform: translateY(-50%);
  transition: width .22s var(--ease), background .22s var(--ease);
}

.coord-axis__tick.is-active {
  color: var(--blue);
}

.coord-axis__tick.is-active::before {
  width: 20px;
  background: var(--orange);
}

/* ---------- 10. 面板 / 说明牌 ---------- */
.panel {
  padding: clamp(20px, 3vw, 34px);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  background: #FFFFFF;
  box-shadow: var(--shadow-card);
}

.panel--mist {
  background: var(--mist);
  box-shadow: none;
}

.panel--paper {
  background: var(--paper);
  border-color: rgba(42, 33, 24, .2);
  border-radius: var(--r-md);
  color: var(--brown);
  box-shadow: none;
}

.panel--ink {
  background: var(--ink);
  border-color: rgba(11, 95, 255, .38);
  color: var(--mist);
  box-shadow: none;
}

.panel--ink .index-label { color: var(--blue-pale); }

/* ---------- 11. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 12px 25px;
  border-radius: var(--pill);
  background: var(--blue);
  color: #FFFFFF;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.03em;
  box-shadow: 0 16px 32px -20px rgba(11, 95, 255, .95);
  transition: transform .18s var(--ease), background .18s var(--ease), box-shadow .18s var(--ease);
}

.btn:hover {
  background: var(--blue-deep);
  transform: translateY(-2px);
}

.btn--ghost {
  background: transparent;
  color: var(--blue);
  border: 1px solid rgba(11, 95, 255, .38);
  box-shadow: none;
}

.btn--ghost:hover { background: var(--blue-pale); }

.btn--warm {
  background: var(--orange);
  color: #22100A;
  box-shadow: 0 16px 32px -20px rgba(255, 106, 43, .95);
}

.btn--warm:hover { background: #FF7F4A; }

/* ---------- 12. 标签 / 徽标 / 索引 ---------- */
.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: var(--pill);
  background: var(--blue-pale);
  color: var(--blue-deep);
  font-size: 12px;
  letter-spacing: 0.06em;
}

.tag--warm {
  background: var(--orange-pale);
  color: #8C3211;
}

.tag--outline {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--graphite);
}

.tag__dot {
  flex: none;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: currentColor;
}

.index-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--blue);
}

.up-mark {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 4px 12px;
  border-radius: var(--pill);
  background: var(--orange-pale);
  color: #B23F12;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
}

.up-mark__dot {
  flex: none;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--orange);
  animation: pulse-dot 3s ease-in-out infinite;
}

/* ---------- 13. 面包屑 ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--graphite);
}

.breadcrumb li:not(:last-child)::after {
  content: "/";
  margin-left: 8px;
  color: var(--line);
}

.breadcrumb a:hover { color: var(--blue); }

/* ---------- 14. 正文 ---------- */
.prose {
  max-width: 38em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--ink);
}

.prose p + p { margin-top: 1.05em; }

.prose h2 {
  margin: 1.7em 0 .6em;
  font-size: clamp(22px, 3vw, 30px);
}

.prose h3 {
  margin: 1.4em 0 .5em;
  font-size: 19px;
}

.prose ul,
.prose ol {
  margin-top: .9em;
  padding-left: 1.2em;
  list-style: disc;
}

.prose li + li { margin-top: .45em; }

.prose a {
  color: var(--blue);
  border-bottom: 1px solid rgba(11, 95, 255, .35);
}

.prose a:hover { border-bottom-color: var(--blue); }

/* ---------- 15. 媒体容器 ---------- */
.media-plate {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 4 / 3;
  border-radius: var(--r-lg);
  overflow: hidden;
  isolation: isolate;
  background: linear-gradient(135deg, var(--blue-pale) 0%, #EEF3FF 56%, var(--orange-pale) 100%);
  border: 1px solid var(--line);
}

.media-plate::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(11, 95, 255, .16) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(11, 95, 255, .16) 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: .55;
}

.media-plate > img,
.media-plate > svg,
.media-plate > .media-plate__img {
  position: absolute;
  inset: 0;
  z-index: 1;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-plate--16x9 { aspect-ratio: 16 / 9; }
.media-plate--1x1 { aspect-ratio: 1 / 1; }
.media-plate--3x4 { aspect-ratio: 3 / 4; }

.figure-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 4 / 3;
  border-radius: var(--r-lg);
  overflow: hidden;
  background: var(--blue-pale);
  border: 1px solid var(--line);
}

.figure-frame--wide { aspect-ratio: 16 / 9; }
.figure-frame--tall { aspect-ratio: 3 / 4; }

.figure-frame__media {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.figure-frame__cap {
  position: absolute;
  left: 14px;
  bottom: 14px;
  padding: 6px 13px;
  border-radius: var(--pill);
  background: rgba(14, 22, 38, .84);
  color: var(--mist);
  font-size: 11px;
  letter-spacing: 0.12em;
}

/* ---------- 16. 显现 / 回到顶部 ---------- */
.reveal {
  transition: opacity .5s var(--ease), transform .5s var(--ease);
}

.reveal.is-pending {
  opacity: 0;
  transform: translateY(14px);
}

.to-top {
  position: fixed;
  right: clamp(14px, 3vw, 28px);
  bottom: clamp(14px, 3vw, 28px);
  z-index: 80;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(11, 95, 255, .5);
  background: var(--ink);
  color: var(--blue-pale);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity .25s var(--ease), transform .25s var(--ease), visibility .25s linear, background .2s var(--ease);
}

.to-top.is-on {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.to-top:hover {
  background: var(--blue);
  color: #FFFFFF;
}

/* ---------- 17. 响应式 ---------- */
@media (max-width: 1080px) {
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 1000px) {
  .foot-band {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 30px 34px;
  }
  .foot-col { padding: 0; border-left: 0; }
}

@media (max-width: 900px) {
  .masthead__inner { padding-top: 20px; }

  .masthead__top {
    grid-template-columns: 1fr;
    justify-items: center;
    gap: 14px;
    text-align: center;
  }

  .masthead__brand { order: -1; }

  .masthead__tagline { justify-content: center; }

  .masthead__meta {
    justify-self: center;
    align-items: center;
    text-align: center;
  }

  .version-sheet {
    right: 50%;
    transform: translateX(50%);
  }

  .nav-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 12px 0 16px;
  }

  .nav-toggle { display: inline-flex; }

  .nav-list {
    order: 3;
    flex: 1 0 100%;
    display: none;
    flex-direction: column;
    gap: 2px;
    margin-top: 10px;
    padding: 10px 0 4px;
    border-top: 1px dashed rgba(220, 232, 255, .2);
  }

  .nav-list[data-open] { display: flex; }

  .nav-link {
    border-radius: var(--r-sm);
    padding: 11px 14px;
    font-size: 15px;
  }

  .nav-link::before { margin-right: 12px; }

  .nav-cta { padding: 9px 17px; font-size: 12.5px; }

  .coord-axis {
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 10px 18px;
    padding: 0 0 0 0;
    border-left: 0;
    border-top: 1px solid var(--line);
    padding-top: 14px;
  }

  .coord-axis__tick { padding-left: 16px; }

  .coord-axis__tick::before { left: 0; }
}

@media (max-width: 720px) {
  body { font-size: 16px; }

  .grid-2,
  .grid-3 { grid-template-columns: 1fr; }

  .foot-band {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .foot-col {
    padding: 20px 0;
    border-top: 1px dashed rgba(227, 231, 240, .18);
  }

  .foot-col:first-child { padding-top: 0; border-top: 0; }

  .site-foot__rev { margin-left: 0; flex: 1 0 100%; }

  .foot-base { justify-content: flex-start; }

  .prose { max-width: 100%; }
}

/* ---------- 18. 可访问性与动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }

  .reveal.is-pending { opacity: 1; transform: none; }

  .to-top { transition: none; }
}