/* 灵瞳文档 · 教程页样式
   配色取自教程截图本身：页面比图深一档，读写区与图同色（--plate #1e1e2e），
   让长图边缘融进页面，只留一道发丝线。主信号色是钨丝琥珀，其余全部退到冷靛灰。 */

:root {
  --ink: #0D1216;
  --ink-deep: #090D10;
  --plate: #1e1e2e;
  --line: rgba(143, 217, 242, .16);
  --line-soft: rgba(143, 217, 242, .08);
  --line-strong: rgba(143, 217, 242, .34);
  --paper: #EAF4F8;
  --paper-dim: #B4C7D0;
  --muted: #6E828C;
  --accent: #0095D9;
  --accent-soft: #8FD9F2;
  --pad: clamp(16px, 4vw, 32px);
  --sans: "Noto Sans SC", "Microsoft YaHei UI", "Microsoft YaHei", system-ui, sans-serif;
  --serif: "Source Han Serif SC", "Noto Serif SC", "STZhongsong", "华文中宋", "Songti SC", serif;
  --tech: "Bahnschrift", "DIN Alternate", "Segoe UI Variable", system-ui, sans-serif;
}

*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  background: var(--ink);
}

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

body {
  margin: 0;
  background: var(--ink);
  color: var(--paper-dim);
  font: 400 15.5px/1.75 var(--sans);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection { background: rgba(0, 149, 217, .26); color: var(--paper); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ── 阅读进度：全页唯一的高饱和元素，细到 2px ── */
.progress {
  position: fixed;
  inset: 0 0 auto;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), var(--accent-soft));
  transform: scaleX(0);
  transform-origin: 0 50%;
  z-index: 60;
  pointer-events: none;
}

/* ── 顶栏 ── */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(13, 18, 22, .9);
  border-bottom: 1px solid var(--line-soft);
  backdrop-filter: blur(14px) saturate(140%);
}

.topbar__inner {
  max-width: 1240px;
  margin: 0 auto;
  padding-inline: var(--pad);
  height: 58px;
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  flex: none;
  gap: 9px;
  color: var(--paper);
  text-decoration: none;
}

.brand__mark {
  filter: drop-shadow(0 0 6px rgba(212, 168, 83, .4));
  width: 22px;
  height: 22px;
  flex: none;
  color: var(--accent);
}

.brand__name {
  white-space: nowrap;
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.02rem;
  letter-spacing: .06em;
}

.topbar__sep {
  width: 1px;
  height: 14px;
  flex: none;
  background: var(--line);
}

.topbar__crumb {
  font-size: .86rem;
  color: var(--paper-dim);
}

.topbar__meta {
  margin-left: auto;
  font-family: var(--tech);
  font-size: .78rem;
  letter-spacing: .05em;
  color: var(--muted);
}

/* ── 版心 ── */
.page {
  max-width: 864px;
  margin: 0 auto;
  padding-inline: var(--pad);
}

/* ── 标题区 ── */
.hero { padding-top: clamp(44px, 7vw, 84px); }

.hero h1 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 600;
  font-size: clamp(2rem, 5.2vw, 2.85rem);
  line-height: 1.18;
  letter-spacing: .015em;
  color: var(--paper);
}

.lead {
  margin: 18px 0 0;
  max-width: 32em;
  font-size: 1rem;
  line-height: 1.85;
}

.lead strong {
  color: var(--paper);
  font-weight: 500;
}

.hero__note {
  margin: 14px 0 0;
  font-size: .86rem;
  color: var(--muted);
}

/* ── 图内目录 ── */
.inside {
  margin-top: clamp(40px, 6vw, 64px);
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.section-head {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 4px 12px;
}

.section-head h2 {
  margin: 0;
  font-family: var(--sans);
  font-size: .92rem;
  font-weight: 500;
  letter-spacing: .04em;
  color: var(--paper);
}

.section-head span {
  font-size: .8rem;
  color: var(--muted);
}

.index {
  list-style: none;
  margin: 6px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  column-gap: clamp(24px, 4vw, 56px);
}

.index li {
  display: flex;
  gap: 14px;
  padding: 15px 0;
  border-bottom: 1px solid var(--line-soft);
}

.index__no {
  flex: none;
  width: 2.4ch;
  font-family: var(--tech);
  font-size: .8rem;
  line-height: 1.95;
  letter-spacing: .03em;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
}

.index__name {
  margin: 0;
  font-size: .95rem;
  font-weight: 500;
  line-height: 1.5;
  color: var(--paper);
}

.index__desc {
  margin: 2px 0 0;
  font-size: .84rem;
  line-height: 1.65;
  color: var(--muted);
}

/* ── 图版 ── */
.plate { margin: clamp(40px, 6vw, 64px) 0 0; scroll-margin-top: 78px; }

.plate__bar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line);
  font-family: var(--tech);
  font-size: .78rem;
  letter-spacing: .04em;
  color: var(--muted);
}

.plate__label { color: var(--paper-dim); }
.plate__dims { font-variant-numeric: tabular-nums; }

.plate__actions {
  margin-left: auto;
  display: flex;
  gap: 8px;
}

.btn {
  display: inline-flex;
  align-items: center;
  padding: 7px 13px;
  border: 1px solid var(--line);
  border-radius: 3px;
  background: transparent;
  color: var(--paper-dim);
  font: 500 .82rem/1.4 var(--sans);
  letter-spacing: .02em;
  text-decoration: none;
  cursor: pointer;
  transition: border-color .16s ease, color .16s ease;
}

.btn:hover {
  border-color: rgba(0, 149, 217, .6);
  color: var(--paper);
}

.plate__link {
  position: relative;
  display: block;
  margin-top: 14px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--plate);
  overflow: hidden;
  transition: border-color .18s ease, box-shadow .18s ease;
}

.plate__link:hover,
.plate__link:focus-visible {
  border-color: #2A4152;
  box-shadow: 0 0 0 1px rgba(0, 149, 217, .22);
}

.plate__link img {
  display: block;
  width: 100%;
  height: auto;
}
/* 图版四角取景框：呼应产品本身的镜头/取景语境，12px，贴在图角上 */
/* 图版四角取景框：呼应产品的镜头/取景语境，12px L 形角标，盖在图角上 */
.plate__corner {
  position: absolute;
  width: 12px;
  height: 12px;
  border: 0 solid rgba(0, 149, 217, .55);
  pointer-events: none;
  z-index: 3;
}

.plate__corner--tl { top: 0; left: 0; border-top-width: 1.5px; border-left-width: 1.5px; }
.plate__corner--tr { top: 0; right: 0; border-top-width: 1.5px; border-right-width: 1.5px; }
.plate__corner--bl { bottom: 0; left: 0; border-bottom-width: 1.5px; border-left-width: 1.5px; }
.plate__corner--br { bottom: 0; right: 0; border-bottom-width: 1.5px; border-right-width: 1.5px; }

/* ── 收尾 ── */
.after {
  margin-top: clamp(48px, 7vw, 72px);
  padding-top: 26px;
  border-top: 1px solid var(--line);
}

.after h2 {
  margin: 0 0 10px;
  font-family: var(--serif);
  font-size: 1.14rem;
  font-weight: 600;
  letter-spacing: .02em;
  color: var(--paper);
}

.after p {
  margin: 0;
  max-width: 36em;
  font-size: .92rem;
  line-height: 1.85;
}

.after a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 149, 217, .35);
}

.after a:hover {
  color: var(--accent-soft);
  border-bottom-color: currentColor;
}

.foot {
  margin-top: clamp(56px, 8vw, 88px);
  padding: 24px 0 56px;
  border-top: 1px solid var(--line-soft);
  font-size: .8rem;
  line-height: 1.8;
  color: var(--muted);
}

.foot p { margin: 0; }
.foot p + p { margin-top: 6px; }

.foot strong {
  color: var(--paper-dim);
  font-weight: 500;
}

/* ── 回顶 ── */
.totop {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 55;
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: rgba(13, 13, 20, .9);
  backdrop-filter: blur(8px);
  color: var(--paper-dim);
  font-size: 1rem;
  cursor: pointer;
  opacity: 0;
  transform: translateY(6px);
  pointer-events: none;
  transition: opacity .18s ease, transform .18s ease, border-color .18s ease, color .18s ease;
}

.totop.is-on {
  opacity: 1;
  transform: none;
  pointer-events: auto;
}

.totop:hover {
  border-color: rgba(0, 149, 217, .6);
  color: var(--paper);
}

/* ── 窄屏 ── */
@media (max-width: 760px) {
  .index { grid-template-columns: 1fr; }
  .topbar__meta { display: none; }
  .lead { font-size: .96rem; }
  .plate__actions { margin-left: 0; width: 100%; }
  .plate__link {
    margin-inline: calc(var(--pad) * -1);
    border-radius: 0;
    border-left: 0;
    border-right: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after { transition: none !important; animation: none !important; }
}