/* components.css · 组件、视图、动效。纸张/印章/信笺质感，不用阴影建层级。 */

/* ---------- 顶栏与骨架（Task 1 保留并修正） ---------- */
.topbar { background: var(--paper); backdrop-filter: none; }
.nav a, .brand { min-width: 44px; min-height: 44px; display: inline-flex; align-items: center; }
.nav a { justify-content: center; }
.skip { position: fixed; top: -80px; left: 20px; z-index: 10000; padding: 12px; background: var(--paper); }
.skip:focus { top: 12px; }
.stage { padding-top: 32px; padding-bottom: 48px; min-height: 48vh; }
.stage h1 { font-size: clamp(32px, 6vw, 56px); max-width: 820px; margin: 16px 0 20px; }
.eyebrow { font-family: var(--mono); font-size: 12px; letter-spacing: .08em; color: var(--ink-muted); margin: 0 0 8px; }
.lede { color: var(--ink-soft); max-width: 680px; font-size: 17px; line-height: 1.85; margin: 0 0 8px; }
#view:focus { outline: none; }

/* ---------- 通用元件 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 44px; padding: 10px 20px;
  border: 1px solid var(--line-strong); border-radius: 2px;
  background: var(--paper-raised); color: var(--ink);
  font-family: var(--sans); font-size: 15px; line-height: 1.4;
  border-bottom: 1px solid var(--line-strong);
  transition: border-color 160ms ease, color 160ms ease, background-color 160ms ease;
}
.btn:hover { border-color: var(--cinnabar); color: var(--cinnabar); }
.btn.ghost { background: transparent; color: var(--ink-muted); }
.btn.ghost:hover { color: var(--cinnabar); }
.linkish {
  border: 0; background: none; color: var(--ink-muted);
  font-size: 13px; padding: 8px 0; border-bottom: 1px solid transparent;
}
.linkish:hover { color: var(--cinnabar); border-bottom-color: var(--cinnabar); }

.sec-title {
  font-family: var(--serif); font-size: 20px; font-weight: 600;
  margin: 48px 0 16px; letter-spacing: .04em;
  display: flex; align-items: center; gap: 12px;
}
.sec-title::after { content: ""; flex: 1; height: 1px; background: var(--line); }

/* 印章 */
.seal {
  width: 44px; height: 44px; flex: 0 0 44px;
  border: 1.5px solid var(--cinnabar); border-radius: 50%;
  display: grid; place-items: center;
  transform: rotate(-6deg); opacity: .85;
}
.seal span {
  writing-mode: vertical-rl; font-family: var(--serif);
  font-size: 12px; letter-spacing: 2px; color: var(--cinnabar);
}

/* 出处 */
.sources {
  font-size: 13px; line-height: 1.8; color: var(--ink-muted);
  border-top: 1px dashed var(--line); padding-top: 12px; margin-top: 16px;
}
.sources-label { color: var(--ink-muted); }
.sources a { color: var(--cinnabar); border-bottom-color: rgba(140, 28, 19, .22); word-break: break-all; }

/* ---------- 首页 ---------- */
.resume {
  display: inline-flex; align-items: center; min-height: 44px;
  margin: 8px 0 4px; padding: 0 14px;
  background: var(--cinnabar-soft); color: var(--cinnabar);
  border: 1px solid rgba(140, 28, 19, .18); border-radius: 2px;
  font-size: 14px;
}
.era-grid {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px; margin: 32px 0 24px; max-width: 760px;
}
.era-btn {
  display: flex; flex-direction: column; align-items: flex-start; justify-content: center;
  gap: 4px; min-height: 88px; padding: 14px 16px;
  background: var(--paper-raised); border: 1px solid var(--line);
  border-radius: 2px; text-align: left;
  transition: border-color 180ms ease, background-color 180ms ease, transform 180ms var(--ease);
}
.era-btn:hover { border-color: var(--cinnabar); background: var(--cinnabar-soft); }
.era-btn:active { transform: translateY(1px); }
.era-short { font-family: var(--serif); font-size: 22px; font-weight: 600; color: var(--ink); letter-spacing: .06em; }
.era-label { font-family: var(--mono); font-size: 12px; color: var(--ink-muted); letter-spacing: .02em; }
.more { margin-top: 8px; font-size: 14px; }

/* ---------- 年代页 ---------- */
.era-head { position: relative; padding-right: 72px; }
.era-head .seal { position: absolute; right: 0; top: 4px; }

.rail-wrap { display: flex; align-items: stretch; gap: 8px; }
.rail {
  flex: 1 1 auto; min-width: 0;
  overflow-x: auto; overflow-y: hidden;
  scroll-snap-type: x proximity;
  scrollbar-width: none; -ms-overflow-style: none;
  -webkit-overflow-scrolling: touch;
}
.rail::-webkit-scrollbar { display: none; }
.rail-track { display: flex; gap: 16px; padding: 4px 2px 12px; }
.rail-item {
  flex: 0 0 auto; width: min(240px, 72vw); min-height: 148px;
  scroll-snap-align: center;
  padding: 18px 18px 16px;
  background: var(--paper-raised); border: 1px solid var(--line); border-radius: 2px;
  display: flex; flex-direction: column; gap: 8px;
}
.rail-item h3 { font-size: 17px; font-weight: 600; line-height: 1.45; }
.rail-year { font-family: var(--mono); font-size: 24px; color: var(--ink); letter-spacing: .02em; font-variant-numeric: tabular-nums; }
.rail-item[data-cat="红色印记"] { border-left: 0; }
.rail-item[data-cat="红色印记"] .rail-year { color: var(--cinnabar); }
.tag {
  margin-top: auto; align-self: flex-start;
  font-size: 12px; color: var(--ink-muted); letter-spacing: .04em;
  border: 1px solid var(--line); border-radius: 2px; padding: 2px 8px;
}
.rail-nav {
  flex: 0 0 44px; width: 44px; min-height: 44px; align-self: center;
  border: 1px solid var(--line); border-radius: 2px;
  background: var(--paper-raised); color: var(--ink-muted); font-size: 16px;
  transition: border-color 160ms ease, color 160ms ease;
}
.rail-nav:hover { border-color: var(--cinnabar); color: var(--cinnabar); }

/* 信笺卡 */
.letters { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; }
.letter-card {
  position: relative; display: flex; flex-direction: column; gap: 12px;
  padding: 22px 22px 20px; min-height: 208px;
  background: var(--paper-raised);
  border: 6px solid #FFFDF7;
  outline: 1px solid rgba(0, 0, 0, .12);
  border-radius: 2px;
  color: var(--ink);
  transition: transform 220ms var(--ease), outline-color 220ms ease;
}
.letter-card:hover { transform: translateY(-2px); outline-color: rgba(140, 28, 19, .35); }
.letter-year {
  font-family: var(--mono); font-size: 12px; letter-spacing: .08em; color: var(--ink-muted);
}
.letter-quote {
  font-family: var(--serif); font-size: 16px; line-height: 1.9; color: var(--ink);
  margin: 0;
}
.letter-quote::first-line { letter-spacing: .02em; }
.letter-open { margin-top: auto; font-size: 13px; color: var(--cinnabar); letter-spacing: .04em; }
.letter-borrow { font-size: 12px; color: var(--ink-muted); }
.letter-card.is-read .letter-year::after { content: " · 已读"; color: var(--ink-muted); }

.era-foot { margin-top: 40px; font-size: 13px; color: var(--ink-muted); }
.era-foot a { color: var(--cinnabar); }

/* ---------- 信笺详情 ---------- */
.letter-sheet {
  position: relative;
  max-width: 680px; margin: 0 auto;
  padding: 48px 48px 56px;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: 2px;
}
.letter-sheet .seal { position: absolute; right: 40px; bottom: 44px; }
.letter-title { font-size: clamp(26px, 4vw, 34px); margin: 0 0 32px; }
.letter-typed {
  font-family: var(--serif); font-size: 19px; line-height: 2.05; color: var(--ink);
  margin: 0; min-height: 3.6em; letter-spacing: .02em; text-wrap: pretty;
}
.letter-typed.is-typing::after {
  content: ""; display: inline-block; width: 1px; height: 1.05em;
  background: var(--ink); margin-left: 3px; vertical-align: -0.14em;
  animation: caret 1s step-end infinite;
}
@keyframes caret { 50% { opacity: 0; } }
.letter-rest hr { border: 0; border-top: 1px solid var(--line); margin: 28px 0; }
.letter-body { font-size: 17px; line-height: 1.95; color: var(--ink-soft); text-indent: 2em; }
.letter-note { font-size: 12px; color: var(--ink-muted); margin-top: 20px; letter-spacing: .02em; }
.letter-actions { max-width: 680px; margin: 32px auto 0; display: flex; gap: 12px; flex-wrap: wrap; }

/* ---------- 年表 ---------- */
.tl-filter {
  display: flex; flex-wrap: wrap; gap: 8px;
  margin: 24px 0 32px; padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}
.tl-chip {
  min-height: 36px; padding: 6px 14px;
  border: 1px solid var(--line); border-radius: 2px;
  background: transparent; color: var(--ink-muted);
  font-size: 13px; transition: all 160ms ease;
}
.tl-chip:hover { border-color: var(--cinnabar); color: var(--cinnabar); }
.tl-chip.is-on { background: var(--cinnabar-soft); border-color: rgba(140, 28, 19, .4); color: var(--cinnabar); }

.tl { list-style: none; margin: 0; padding: 0; position: relative; }
.tl::before {
  content: ""; position: absolute; left: 95px; top: 8px; bottom: 8px;
  width: 1px; background: var(--line);
}
.tl-item {
  display: grid; grid-template-columns: 76px 24px minmax(0, 1fr);
  gap: 8px; align-items: start; padding: 14px 0;
}
.tl-item[hidden] { display: none; }
.tl-year {
  font-family: var(--mono); font-size: 13px; color: var(--ink-muted);
  text-align: right; padding-top: 2px; font-variant-numeric: tabular-nums;
}
.tl-dot {
  width: 7px; height: 7px; margin: 6px auto 0;
  border: 1px solid var(--ink-muted); border-radius: 50%; background: var(--paper);
  position: relative; z-index: 1;
}
.tl-dot.is-red { width: 9px; height: 9px; margin-top: 5px; border-color: var(--cinnabar); background: var(--cinnabar); }
.tl-main h3 { font-size: 17px; font-weight: 600; margin: 0 0 4px; }
.tl-brief { font-size: 14px; line-height: 1.8; color: var(--ink-muted); margin: 0 0 6px; max-width: 680px; }
.tl-more { font-size: 12px; color: var(--cinnabar); padding: 6px 0; min-height: 32px; }
.tl-full { margin-top: 8px; padding: 14px 16px; background: var(--paper-raised); border-left: 1px solid var(--line); }
.tl-body { font-size: 15px; line-height: 1.95; color: var(--ink-soft); margin: 0; }
.tl-flag { font-size: 12px; color: var(--ink-muted); margin: 10px 0 0; }
.tl-full .sources { margin-top: 12px; padding-top: 10px; }

/* ---------- 时光问答 ---------- */
.ask-form { display: flex; gap: 8px; margin: 28px 0 20px; max-width: 680px; }
.ask-form input {
  flex: 1 1 auto; min-width: 0; min-height: 44px;
  padding: 10px 14px; font-family: var(--sans); font-size: 16px; color: var(--ink);
  background: var(--paper-raised); border: 1px solid var(--line-strong); border-radius: 2px;
  transition: border-color 160ms ease;
}
.ask-form input::placeholder { color: var(--ink-muted); opacity: .8; }
.ask-form input:focus { border-color: var(--cinnabar); outline: none; }

.ask-chips { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 8px; max-width: 1080px; }
.ask-chip {
  text-align: left; min-height: 44px; padding: 10px 14px;
  background: var(--paper-raised); border: 1px solid var(--line); border-radius: 2px;
  color: var(--ink-soft); font-size: 14px; line-height: 1.6;
  transition: border-color 160ms ease, color 160ms ease;
}
.ask-chip:hover { border-color: var(--cinnabar); color: var(--cinnabar); }
.ask-more { display: flex; gap: 8px; margin: 16px 0 8px; flex-wrap: wrap; }

.ask-result { margin-top: 32px; border-top: 1px solid var(--line); padding-top: 24px; }
.ask-head { margin-bottom: 16px; }
.ask-q { font-family: var(--serif); font-size: 17px; color: var(--ink); }
.ask-card { max-width: 780px; }
.ask-title { font-size: 15px; color: var(--ink-muted); font-weight: 600; margin: 24px 0 12px; letter-spacing: .04em; }
.ask-node { padding: 20px 0; border-bottom: 1px dashed var(--line); }
.ask-node:last-child { border-bottom: 0; }
.ask-node h3 { font-size: 20px; margin: 4px 0 10px; }
.ask-node p { font-size: 16px; line-height: 1.9; color: var(--ink-soft); }
.ask-miss { padding: 20px 22px; background: var(--paper-raised); border: 1px solid var(--line); border-radius: 2px; }
.ask-fallback { font-family: var(--serif); font-size: 18px; color: var(--ink); margin: 0 0 8px; }
.ask-hint { font-size: 14px; color: var(--ink-muted); margin: 0; }
.ask-again { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 24px; }

/* ---------- 纪念卡 ---------- */
.card-wrap { max-width: 420px; margin: 28px 0 20px; }
.card-wrap canvas {
  width: 100%; height: auto; display: block;
  background: var(--paper-raised);
  border: 6px solid #FFFDF7; outline: 1px solid rgba(0, 0, 0, .12);
  border-radius: 2px;
}
.card-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 16px; }
.card-reset { margin-top: 24px; }

/* ---------- 动效（全部只在 .js-anim 下生效，JS 失败时按终态显示） ---------- */
.js-anim .reveal { opacity: 0; transform: translateY(10px); }
.js-anim .reveal.is-in {
  opacity: 1; transform: none;
  transition: opacity 320ms ease-out, transform 320ms var(--ease);
}
.js-anim .veil { filter: grayscale(.6) contrast(.85) brightness(1.15); opacity: 0; }
.js-anim .veil.is-veiled {
  filter: none; opacity: 1;
  transition: filter 700ms ease-out, opacity 700ms ease-out;
}

/* A1 信笺展开 */
.js-anim .letter-sheet { clip-path: inset(0 0 100% 0); opacity: .001; }
.js-anim .letter-sheet.is-open {
  clip-path: inset(0); opacity: 1;
  transition: clip-path 520ms var(--ease), opacity 320ms ease-out;
}
/* A4 印章落下 */
.js-anim .letter-sheet .seal { opacity: 0; transform: scale(1.9) rotate(-18deg); }
.js-anim .letter-sheet.is-stamped .seal {
  opacity: .88; transform: scale(1) rotate(-6deg);
  transition: transform 260ms cubic-bezier(.34, 1.56, .64, 1) 80ms, opacity 140ms ease-out 80ms;
}
/* 正文淡入 */
.js-anim .letter-rest { opacity: 0; }
.js-anim .letter-rest.is-shown {
  opacity: 1; transition: opacity 240ms ease-out;
}

/* ---------- 移动端 ---------- */
@media (max-width: 900px) {
  .letters { grid-template-columns: 1fr; }
  .ask-chips { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 760px) {
  .stage h1 { font-size: clamp(28px, 8vw, 40px); }
  .era-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
  .era-btn { min-height: 76px; padding: 12px 14px; }
  .era-short { font-size: 19px; }
  .era-head { padding-right: 0; }
  .era-head .seal { position: static; margin-top: 12px; }
  .letter-sheet { padding: 28px 22px 40px; }
  .letter-sheet .seal { right: 20px; bottom: 24px; }
  .letter-typed { font-size: 17px; line-height: 1.95; }
  .ask-chips { grid-template-columns: 1fr; }
  .ask-form { flex-direction: column; }
  .ask-form .btn { width: 100%; }
  .tl::before { left: 61px; }
  .tl-item { grid-template-columns: 48px 20px minmax(0, 1fr); gap: 6px; }
  .tl-year { font-size: 12px; }
  .card-wrap { max-width: 100%; }
  .rail-item { width: min(200px, 68vw); }
}
@media (max-width: 560px) {
  .topbar { flex-wrap: wrap; gap: 6px; position: relative; padding: 10px 16px; }
  .brand { width: 100%; min-height: 32px; font-size: 14px; }
  .nav { width: 100%; gap: 2px; justify-content: space-between; }
  /* 四项必须挤在一行且都不溢出：均分 + 允许收缩 */
  .nav a { flex: 1 1 0; min-width: 0; padding: 8px 2px; font-size: 12px; text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
  .js-anim .reveal, .js-anim .veil, .js-anim .letter-rest { opacity: 1 !important; transform: none !important; filter: none !important; }
  .js-anim .letter-sheet { clip-path: none !important; opacity: 1 !important; }
  .js-anim .letter-sheet .seal { opacity: .88 !important; transform: rotate(-6deg) !important; }
}