/* ==========================================================================
   28CN 加彩预测站 — 共享样式表 /assets/site.css
   侧边轨道导航 + 杂志编号章节 + 玻璃/实色并置
   ========================================================================== */

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

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

body,
h1, h2, h3, h4, h5, h6,
p, figure, blockquote, dl, dd, ul, ol {
  margin: 0;
}

ul, ol {
  padding: 0;
  list-style: none;
}

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

button, input, select, textarea {
  font: inherit;
  color: inherit;
}

button {
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

table {
  border-collapse: collapse;
  border-spacing: 0;
}

/* ---------- 2. 设计令牌 ---------- */
:root {
  /* 色彩 */
  --ink-900: #0B1220;
  --ink-800: #111A2E;
  --ink-950: #14181F;
  --paper: #F4F1EC;
  --mist: #E9EEF7;
  --slate: #8E9BB3;
  --maple: #E23A2E;
  --maple-deep: #B2231B;
  --cyan: #27E0D0;
  --amber: #F2B33D;
  --glass: rgba(255, 255, 255, 0.08);
  --glass-strong: rgba(255, 255, 255, 0.14);
  --grid-line: rgba(255, 255, 255, 0.06);

  /* 字体 */
  --font-display: "Space Grotesk", "Sora", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", Georgia, serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Courier New", monospace;
  --font-body: -apple-system, BlinkMacSystemFont, "Inter", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;

  /* 六级字号阶梯（1.25 倍率） */
  --step--1: 0.8rem;
  --step-0: 1rem;
  --step-1: 1.25rem;
  --step-2: 1.5625rem;
  --step-3: 1.953rem;
  --step-4: 2.441rem;

  /* 空间尺度 */
  --rail-w: 236px;
  --topbar-h: 58px;
  --w-wide: 1280px;
  --w-mid: 1040px;
  --w-narrow: 720px;
  --notch: 12px;
  --gap-module: clamp(32px, 5vw, 64px);

  /* 动效 */
  --dur: 120ms;
  --dur-slow: 240ms;
  --ease: cubic-bezier(0.2, 0.7, 0.3, 1);
}

/* ---------- 3. 基础排版 ---------- */
body {
  min-height: 100vh;
  padding-top: var(--topbar-h);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  color: var(--mist);
  background-color: var(--ink-900);
  background-image:
    radial-gradient(circle at 84% 6%, rgba(226, 58, 46, 0.10), transparent 46%),
    radial-gradient(circle at 10% 92%, rgba(39, 224, 208, 0.07), transparent 44%),
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: auto, auto, 72px 72px, 72px 72px;
  background-repeat: no-repeat, no-repeat, repeat, repeat;
  background-attachment: fixed, fixed, scroll, scroll;
  -webkit-font-smoothing: antialiased;
}

@media (min-width: 768px) {
  body { font-size: 17px; }
}

@media (min-width: 1024px) {
  body {
    padding-top: 0;
    padding-left: var(--rail-w);
  }
}

@media (max-width: 1023.98px) {
  html.is-nav-open,
  html.is-nav-open body { overflow: hidden; }
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.16;
  letter-spacing: -0.02em;
  color: var(--mist);
}

h1 { font-size: clamp(2.2rem, 5.4vw, 4.05rem); }
h2 { font-size: clamp(1.6rem, 3vw, 2.4rem); }
h3 { font-size: var(--step-1); }
h4 { font-size: var(--step-0); }

p { max-width: 34em; }

a {
  color: var(--cyan);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

strong, b { color: #ffffff; font-weight: 700; }

::selection {
  background: var(--maple);
  color: #ffffff;
}

/* ---------- 4. 焦点与可访问性 ---------- */
:focus { outline: none; }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
  border-radius: 2px;
}

.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: fixed;
  top: 10px;
  left: 10px;
  z-index: 200;
  padding: 11px 18px;
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: #ffffff;
  text-decoration: none;
  background: var(--maple);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 9px), calc(100% - 9px) 100%, 0 100%);
  transform: translateY(-180%);
  transition: transform 160ms var(--ease);
}

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

/* ---------- 5. 容器与网格 ---------- */
.container {
  width: 100%;
  max-width: var(--w-wide);
  margin-inline: auto;
  padding-inline: clamp(20px, 4vw, 40px);
}

.container--mid { max-width: var(--w-mid); }
.container--narrow { max-width: var(--w-narrow); }

.grid {
  display: grid;
  gap: 24px;
}

@media (min-width: 640px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 900px) {
  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

/* ---------- 6. 头部：顶栏 ---------- */
.site-header { position: relative; z-index: 100; }

.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 90;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  height: var(--topbar-h);
  padding-inline: 14px;
  background: rgba(11, 18, 32, 0.88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--grid-line);
}

.topbar__brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  text-decoration: none;
}

.brand-mark {
  display: inline-grid;
  place-items: center;
  padding: 7px 10px;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.06em;
  color: #ffffff;
  background: linear-gradient(135deg, var(--maple), var(--maple-deep));
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%);
  flex: 0 0 auto;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 0.92rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--mist);
  white-space: nowrap;
}

.brand-tagline {
  font-family: var(--font-body);
  font-size: 0.72rem;
  line-height: 1.55;
  letter-spacing: 0.01em;
  color: var(--slate);
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 9px 13px;
  background: var(--glass);
  border: 1px solid var(--grid-line);
  color: var(--mist);
  font-family: var(--font-display);
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 9px), calc(100% - 9px) 100%, 0 100%);
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.nav-toggle:hover {
  background: var(--glass-strong);
  border-color: var(--cyan);
  color: #ffffff;
}

.nav-toggle__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 3px;
  width: 15px;
}

.nav-toggle__grid i {
  display: block;
  height: 2px;
  background: currentColor;
}

.nav-toggle__text { line-height: 1; }

/* ---------- 7. 头部：遮罩 ---------- */
.rail-scrim {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(11, 18, 32, 0.76);
  backdrop-filter: blur(2px);
  -webkit-backdrop-filter: blur(2px);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--dur-slow) var(--ease), visibility var(--dur-slow) var(--ease);
}

.rail-scrim[data-open="true"] {
  opacity: 1;
  visibility: visible;
}

@media (min-width: 1024px) {
  .rail-scrim { display: none; }
}

/* ---------- 8. 头部：侧边轨道 ---------- */
.rail {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 110;
  display: flex;
  flex-direction: column;
  width: min(84vw, 300px);
  padding: 18px 16px 24px;
  overflow-y: auto;
  overscroll-behavior: contain;
  background:
    linear-gradient(180deg, rgba(226, 58, 46, 0.10) 0%, transparent 26%),
    linear-gradient(180deg, var(--ink-900) 0%, var(--ink-800) 100%);
  border-right: 1px solid var(--grid-line);
  transform: translateX(-102%);
  transition: transform var(--dur-slow) var(--ease);
}

.rail[data-open="true"] { transform: translateX(0); }

.rail__top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 10px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--grid-line);
}

.rail__brand {
  display: flex;
  align-items: flex-start;
  gap: 11px;
  min-width: 0;
  text-decoration: none;
}

.brand-copy {
  display: flex;
  flex-direction: column;
  gap: 5px;
  min-width: 0;
}

.rail__close {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  flex: 0 0 auto;
  font-size: 0.8rem;
  color: var(--slate);
  background: var(--glass);
  border: 1px solid var(--grid-line);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.rail__close:hover {
  color: var(--mist);
  border-color: var(--cyan);
}

.rail__nav {
  flex: 1 1 auto;
  padding-top: 16px;
}

.nav-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav-link {
  display: grid;
  grid-template-columns: 2.1em minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  padding: 11px 12px 11px 13px;
  color: var(--mist);
  text-decoration: none;
  border-left: 3px solid transparent;
  font-family: var(--font-display);
  font-size: 0.94rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.nav-link__num {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--slate);
  font-variant-numeric: tabular-nums;
  transition: color var(--dur) var(--ease);
}

.nav-link__label { min-width: 0; }

.nav-link:hover {
  background: var(--glass);
  border-left-color: var(--cyan);
  color: #ffffff;
}

.nav-link:hover .nav-link__num { color: var(--cyan); }

.nav-link[aria-current="page"] {
  border-left-color: var(--maple);
  color: #ffffff;
  background: linear-gradient(90deg, rgba(226, 58, 46, 0.18), rgba(226, 58, 46, 0));
}

.nav-link[aria-current="page"] .nav-link__num { color: var(--maple); }

.rail__foot {
  margin-top: auto;
  padding-top: 20px;
  border-top: 1px solid var(--grid-line);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.rail__status {
  display: flex;
  align-items: center;
  gap: 9px;
  margin: 0 0 4px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  line-height: 1.5;
  color: var(--slate);
}

.rail__status .dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 4px rgba(39, 224, 208, 0.14);
}

.rail__sub {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  color: var(--slate);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  align-self: flex-start;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.rail__sub:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* 桌面端：轨道常驻 */
@media (min-width: 1024px) {
  .topbar { display: none; }

  .rail {
    width: var(--rail-w);
    padding: 26px 18px 26px;
    transform: none;
  }

  .rail__close { display: none; }
}

/* ---------- 9. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 18px;
  font-family: var(--font-display);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  line-height: 1;
  text-decoration: none;
  color: #ffffff;
  background: var(--maple);
  border: 1px solid transparent;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%);
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease),
              color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

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

.btn:active { transform: translateY(0); }

.btn--ghost {
  background: var(--glass);
  border-color: var(--grid-line);
  color: var(--mist);
}

.btn--ghost:hover {
  background: var(--glass-strong);
  border-color: var(--cyan);
  color: #ffffff;
}

.btn--cyan {
  background: transparent;
  border-color: var(--cyan);
  color: var(--cyan);
}

.btn--cyan:hover {
  background: rgba(39, 224, 208, 0.12);
  border-color: var(--cyan);
  color: var(--cyan);
}

.btn[disabled],
.btn[aria-disabled="true"] {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
}

/* ---------- 10. 卡片与面板 ---------- */
.card {
  position: relative;
  padding: 22px;
  background: var(--glass);
  border: 1px solid var(--grid-line);
  clip-path: polygon(0 0, calc(100% - var(--notch)) 0, 100% var(--notch), 100% 100%, 0 100%);
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease),
              background var(--dur) var(--ease);
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--cyan);
  background: rgba(39, 224, 208, 0.06);
}

.card--solid {
  background: var(--ink-800);
  border-color: rgba(255, 255, 255, 0.08);
}

.card--solid:hover {
  background: var(--ink-800);
  border-color: var(--cyan);
}

.card--paper {
  background: var(--paper);
  border-color: rgba(20, 24, 31, 0.12);
  color: var(--ink-950);
}

.card--paper:hover {
  background: var(--paper);
  border-color: var(--cyan);
}

.card--paper h2,
.card--paper h3,
.card--paper h4,
.card--paper strong { color: var(--ink-950); }

.card--paper p { color: #3B4250; }

/* ---------- 11. 标签与数据字 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 9px;
  font-family: var(--font-mono);
  font-size: 0.67rem;
  font-weight: 600;
  line-height: 1;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--amber);
  border: 1px solid rgba(242, 179, 61, 0.35);
  background: rgba(242, 179, 61, 0.06);
}

.tag--cyan {
  color: var(--cyan);
  border-color: rgba(39, 224, 208, 0.35);
  background: rgba(39, 224, 208, 0.06);
}

.tag--maple {
  color: var(--maple);
  border-color: rgba(226, 58, 46, 0.4);
  background: rgba(226, 58, 46, 0.08);
}

.mono,
.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

.num--amber { color: var(--amber); }
.num--cyan { color: var(--cyan); }

/* ---------- 12. 标题与编号章节 ---------- */
.section-title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(1.35rem, 2.4vw, 1.9rem);
  line-height: 1.4;
  letter-spacing: -0.01em;
  color: var(--mist);
}

.section-kicker {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--slate);
}

.chapter-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(2.4rem, 6vw, 4.4rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  color: transparent;
  -webkit-text-stroke: 1px var(--slate);
  transition: -webkit-text-stroke-color var(--dur-slow) var(--ease);
}

.chapter-num.is-visible,
[data-reveal].is-visible .chapter-num {
  -webkit-text-stroke-color: var(--maple);
}

.text-slate { color: var(--slate); }
.text-mist { color: var(--mist); }
.text-paper { color: var(--paper); }
.lead {
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 1.6vw, 1.3rem);
  line-height: 1.6;
  letter-spacing: -0.01em;
  color: var(--mist);
}

/* ---------- 13. 面包屑 ---------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.breadcrumb a {
  color: var(--slate);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}

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

.breadcrumb li:not(:last-child)::after {
  content: "/";
  margin-left: 8px;
  color: var(--slate);
  opacity: 0.5;
}

.breadcrumb [aria-current="page"] { color: var(--mist); }

/* ---------- 14. 图片容器（供页面阶段放置图片） ---------- */
.media {
  position: relative;
  display: block;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background-color: var(--ink-800);
  background-image:
    radial-gradient(circle at 78% 22%, rgba(226, 58, 46, 0.18), transparent 52%),
    radial-gradient(circle at 18% 84%, rgba(39, 224, 208, 0.14), transparent 50%);
  border: 1px solid var(--grid-line);
  clip-path: polygon(0 0, calc(100% - var(--notch)) 0, 100% var(--notch), 100% 100%, 0 100%);
}

.media > img,
.media > picture > img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 34px 34px;
  opacity: 0.85;
}

.media--wide { aspect-ratio: 21 / 9; }
.media--tablet { aspect-ratio: 4 / 3; }
.media--square { aspect-ratio: 1 / 1; }
.media--tall { aspect-ratio: 3 / 4; }

.media__caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  color: var(--slate);
}

/* ---------- 15. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: var(--gap-module);
  padding: clamp(40px, 6vw, 64px) clamp(20px, 4vw, 40px) 26px;
  background:
    linear-gradient(180deg, rgba(226, 58, 46, 0.07) 0%, transparent 30%),
    var(--ink-900);
  border-top: 1px solid var(--grid-line);
  font-family: var(--font-mono);
  color: var(--mist);
}

.footer-grid {
  width: 100%;
  max-width: var(--w-wide);
  margin-inline: auto;
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
}

@media (min-width: 640px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1024px) {
  .footer-grid { grid-template-columns: 1.5fr 1fr 1fr 1.25fr; gap: 40px; }
}

.footer-brand {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
}

.footer-brand__name {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--mist);
}

.footer-brand__note {
  margin: 0;
  max-width: 22em;
  font-size: 0.75rem;
  line-height: 1.8;
  color: var(--slate);
}

.footer-col__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--slate);
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-col a {
  font-size: 0.84rem;
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.footer-col a:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

.footer-contact {
  margin: 0;
  max-width: 26em;
  font-size: 0.78rem;
  line-height: 2;
  letter-spacing: 0.02em;
  color: var(--slate);
  word-break: break-word;
}

.footer-texture {
  width: 100%;
  max-width: var(--w-wide);
  height: 12px;
  margin: 36px auto 18px;
  opacity: 0.7;
  background-image:
    repeating-linear-gradient(90deg, rgba(255, 255, 255, 0.10) 0 1px, transparent 1px 22px),
    linear-gradient(90deg, rgba(226, 58, 46, 0.55) 0%, rgba(242, 179, 61, 0.28) 48%, rgba(39, 224, 208, 0.45) 100%);
  clip-path: polygon(0 0, 100% 0, calc(100% - 12px) 100%, 0 100%);
}

.footer-base {
  width: 100%;
  max-width: var(--w-wide);
  margin-inline: auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--slate);
}

.footer-copy,
.footer-icp { margin: 0; max-width: none; }

/* ---------- 16. 进场与浮动返回顶部 ---------- */
[data-reveal] {
  opacity: 0;
  translate: 0 12px;
  transition: opacity 400ms var(--ease), translate 400ms var(--ease);
}

[data-reveal].is-visible {
  opacity: 1;
  translate: 0 0;
}

.to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 95;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  line-height: 1;
  color: var(--cyan);
  background: var(--ink-800);
  border: 1px solid var(--grid-line);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 200ms var(--ease), transform 200ms var(--ease),
              visibility 200ms var(--ease), border-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}

.to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.to-top:hover,
.to-top:focus-visible {
  border-color: var(--cyan);
  color: #ffffff;
}

/* ---------- 17. 减弱动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  [data-reveal] {
    opacity: 1;
    translate: 0 0;
  }

  .card:hover,
  .btn:hover {
    transform: none;
  }
}