/* ==========================================================================
   《一颗苹果的一百五十年》— 视觉与版式
   设计原则：纸是底的，红是墨，留白是呼吸。
   场景现在是 AI 生成的关键帧，边框回纹是图里自带的，别裁。
   ========================================================================== */

:root {
  --paper:      #f3ede1;   /* 页面底色 */
  --paper-deep: #e7ddc9;
  --paper-edge: #d8cbb2;
  --sheet:      #faf5e9;   /* 作品纸面 */
  --ink:        #2a2521;
  --ink-soft:   #6f655a;
  --ink-faint:  #9c9184;
  --red:        #a83a2e;
  --red-deep:   #7d2820;

  --serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", serif;
  --kai:   "Kaiti SC", "STKaiti", "KaiTi", "Noto Serif SC", serif;

  --ease: cubic-bezier(.22, .61, .36, 1);
  --scene-ratio: 3 / 2;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.95;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* 宣纸纤维：一层极淡的噪点，让屏幕不像屏幕 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: .45;
  mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='180' height='180' filter='url(%23n)' opacity='0.2'/%3E%3C/svg%3E");
}

/* --------------------------------------------------------------------------
   进度条 / 章节导航
   -------------------------------------------------------------------------- */

.progress {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 2px;
  z-index: 60;
}
.progress i {
  display: block;
  height: 100%;
  width: 0;
  background: var(--red);
  transition: width .1s linear;
}

.rail {
  position: fixed;
  top: 50%;
  left: 26px;
  transform: translateY(-50%);
  z-index: 55;
  display: flex;
  flex-direction: column;
  gap: 26px;
  opacity: 0;
  transition: opacity .6s var(--ease);
}
body.stage-on .rail { opacity: 1; }

.rail a { display: block; padding: 6px 0; text-decoration: none; }
.rail a span {
  display: block;
  width: 18px;
  height: 1px;
  background: var(--ink-faint);
  transition: width .35s var(--ease), background .3s var(--ease);
}
.rail a:hover span { width: 28px; }
.rail a.is-active span { width: 34px; background: var(--red); }

/* --------------------------------------------------------------------------
   舞台：一张张剪纸作品
   -------------------------------------------------------------------------- */

.stage {
  position: fixed;
  top: 0; right: 0;
  width: 54vw;
  height: 100vh;
  z-index: 1;
  display: grid;
  place-items: center;
  pointer-events: none;
  opacity: 0;
  transition: opacity .7s var(--ease);
}
body.stage-on .stage { opacity: 1; }

.paper-frame {
  position: relative;
  width: min(86%, 620px);
  aspect-ratio: var(--scene-ratio);
  background: var(--sheet);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, .8) inset,
    0 30px 60px -28px rgba(90, 68, 40, .5),
    0 4px 14px -6px rgba(90, 68, 40, .18);
  transform-origin: 50% 50%;
  transition: transform .2s linear, box-shadow .6s var(--ease);
}

/* 第五章的反转：整块画面收缩成一张纸 */
body.is-reveal .paper-frame {
  box-shadow:
    0 1px 0 rgba(255, 255, 255, .9) inset,
    0 40px 80px -30px rgba(60, 44, 26, .62),
    0 6px 18px -8px rgba(60, 44, 26, .28);
}

.stage-inner {
  position: absolute;
  inset: 0;
  transform-origin: 50% 50%;
}

.scene {
  position: absolute;
  inset: 0;
  opacity: 0;
  visibility: hidden;
  transform: scale(.985);
  transition: opacity .9s var(--ease), transform .9s var(--ease), visibility .9s;
}
.scene.is-active {
  opacity: 1;
  visibility: visible;
  transform: scale(1);
}

/* contain 而不是 cover：回纹边框一个像素都不能裁 */
.scene img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

/* --------------------------------------------------------------------------
   首屏
   -------------------------------------------------------------------------- */

.hero {
  position: relative;
  z-index: 2;
  min-height: 100vh;
  display: grid;
  align-items: center;
  padding: 8vh 6vw;
}

.hero-inner { max-width: 40rem; }

.eyebrow {
  margin: 0 0 2rem;
  font-size: 12px;
  letter-spacing: .42em;
  color: var(--ink-faint);
}

.hero h1 {
  margin: 0;
  font-family: var(--kai);
  font-weight: 400;
  font-size: clamp(2.9rem, 5.6vw, 4.8rem);
  line-height: 1.26;
  letter-spacing: .04em;
}

.hero-sub {
  margin: 2.2rem 0 0;
  font-size: clamp(.95rem, 1.4vw, 1.05rem);
  color: var(--ink-soft);
  letter-spacing: .1em;
}

.hero-quote {
  margin: 3.6rem 0 0;
  padding-left: 1.4rem;
  border-left: 2px solid var(--red);
  font-family: var(--kai);
  font-size: clamp(1.05rem, 1.8vw, 1.25rem);
  line-height: 1.9;
  color: var(--red-deep);
}

.scroll-hint {
  margin-top: 4.4rem;
  display: flex;
  align-items: center;
  gap: .9rem;
  font-size: 12px;
  letter-spacing: .3em;
  color: var(--ink-faint);
}
.scroll-hint span {
  display: block;
  width: 1px;
  height: 46px;
  background: linear-gradient(to bottom, var(--ink-faint), transparent);
  animation: drip 2.4s var(--ease) infinite;
}
@keyframes drip {
  0%   { transform: scaleY(.2); transform-origin: top; opacity: 0; }
  40%  { transform: scaleY(1);  transform-origin: top; opacity: 1; }
  100% { transform: scaleY(1);  transform-origin: top; opacity: 0; }
}

/* --------------------------------------------------------------------------
   正文：左侧文字，右侧剪纸
   -------------------------------------------------------------------------- */

.scrolly {
  position: relative;
  z-index: 2;
  padding-bottom: 10vh;
}

.copy {
  width: min(42vw, 32rem);
  margin-left: max(9vw, 7rem);
}

/* 段落浮起：读起来像纸页一张张翻过去 */
html.js .ch > * {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity .9s var(--ease), transform .9s var(--ease);
}
html.js .ch > *.is-visible {
  opacity: 1;
  transform: none;
}

.ch {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 14vh 0;
}

.ch-kicker {
  margin: 0;
  font-size: 11px;
  letter-spacing: .44em;
  color: var(--ink-faint);
}

.ch h2 {
  margin: .6rem 0 0;
  font-family: var(--kai);
  font-weight: 400;
  font-size: clamp(2.2rem, 4vw, 3.2rem);
  letter-spacing: .12em;
  color: var(--red-deep);
}

.ch-year {
  margin: .4rem 0 2.4rem;
  font-size: 12px;
  letter-spacing: .24em;
  color: var(--ink-faint);
}

.ch p { margin: 0 0 1.3rem; color: #3a332c; }

.ch .lead {
  font-family: var(--kai);
  font-size: clamp(1.22rem, 2.1vw, 1.5rem);
  line-height: 1.85;
  color: var(--ink);
}

.ch .punch {
  margin-top: 2.8rem;
  padding-top: 1.8rem;
  border-top: 1px solid var(--paper-edge);
  font-family: var(--kai);
  font-size: clamp(1.3rem, 2.3vw, 1.65rem);
  letter-spacing: .1em;
  color: var(--red);
}

.facts {
  list-style: none;
  margin: 2.6rem 0 0;
  padding: 0;
  border-top: 1px solid var(--paper-edge);
}
.facts li {
  padding: .9rem 0;
  border-bottom: 1px solid var(--paper-edge);
  font-size: .86rem;
  line-height: 1.8;
  color: var(--ink-soft);
}
.facts b {
  display: inline-block;
  min-width: 5.4em;
  margin-right: 1.1em;
  font-weight: 400;
  font-size: .76rem;
  letter-spacing: .14em;
  color: var(--red);
}

/* --------------------------------------------------------------------------
   页脚
   -------------------------------------------------------------------------- */

.site-footer {
  position: relative;
  z-index: 2;
  margin-top: 6vh;
  padding: 9vh 6vw 6vh;
  background: var(--paper-deep);
  border-top: 1px solid var(--paper-edge);
}

.footer-inner { max-width: 62rem; }

.site-footer h3 {
  margin: 0 0 1.4rem;
  font-family: var(--kai);
  font-weight: 400;
  font-size: 1.6rem;
  letter-spacing: .18em;
  color: var(--red-deep);
}

.site-footer p { color: var(--ink-soft); font-size: .92rem; }

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 3rem;
  margin: 3.2rem 0;
}
.footer-cols h4 {
  margin: 0 0 .9rem;
  font-size: 12px;
  font-weight: 400;
  letter-spacing: .26em;
  color: var(--ink-faint);
}
.footer-cols ul {
  margin: 0;
  padding-left: 1.1rem;
  font-size: .84rem;
  line-height: 2;
  color: var(--ink-soft);
}

.qr-slot {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  margin-top: 2.6rem;
}
.qr-box {
  width: 84px;
  height: 84px;
  display: grid;
  place-items: center;
  border: 1px dashed var(--ink-faint);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--ink-faint);
}
.qr-slot p { margin: 0; font-size: .82rem; color: var(--ink-faint); }

.copyright {
  margin-top: 3.4rem !important;
  padding-top: 1.6rem;
  border-top: 1px solid var(--paper-edge);
  font-size: .76rem !important;
  letter-spacing: .16em;
  color: var(--ink-faint) !important;
}

/* --------------------------------------------------------------------------
   移动端的内联场景位：桌面端永远空着
   -------------------------------------------------------------------------- */

.ch-scene { display: none; }

/* --------------------------------------------------------------------------
   窄屏：剪纸跟着每一章走
   -------------------------------------------------------------------------- */

@media (max-width: 900px) {
  body { font-size: 16px; }

  /* 钉不住的画就别钉了，改成每章一张 */
  .stage { display: none; }
  .rail { display: none; }

  .ch-scene {
    display: block;
    margin: 0 0 2.2rem;
  }
  .ch-scene .scene {
    position: static;
    inset: auto;
    width: 100%;
    aspect-ratio: var(--scene-ratio);
    opacity: 1;
    visibility: visible;
    transform: none;
    background: var(--sheet);
    box-shadow:
      0 1px 0 rgba(255, 255, 255, .8) inset,
      0 22px 44px -26px rgba(90, 68, 40, .5),
      0 4px 12px -6px rgba(90, 68, 40, .18);
  }

  .copy {
    width: min(100%, 34rem);
    margin: 0 auto;
    padding: 0 7vw;
  }

  .ch {
    min-height: auto;
    padding: 5vh 0 9vh;
  }

  .hero { padding-top: 10vh; padding-bottom: 6vh; }
  .scroll-hint { margin-top: 3rem; }

  .footer-cols { grid-template-columns: 1fr; gap: 2rem; }
}

/* --------------------------------------------------------------------------
   无障碍：尊重「减少动态效果」
   -------------------------------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .scroll-hint span { animation: none; }
  .scene, .stage, .paper-frame, .rail a span { transition: none; }
}