/* =========================================================
   LAYFLAT 180 — 纸本编辑风格 · 纯静态原型
   tokens 与设计契约一致：米纸 / 墨黑 / 靛蓝 / 赭石
   ========================================================= */

:root {
  --paper: #f6f1e4;
  --paper-2: #ede4d1;
  --surface: #fcf9f1;
  --surface-2: #f3ecdc;
  --ink: #1e1b16;
  --ink-2: #5b5348;
  --ink-3: #8c8476;
  --line: #d8cfba;
  --line-strong: #c3b79c;
  --thread: #2c4c8a;
  --thread-soft: #e3e9f5;
  --ochre: #b0603a;
  --ok: #3f5c49;

  --serif: Georgia, "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --mono: "SFMono-Regular", "Consolas", "Menlo", monospace;

  --r-sm: 2px;
  --r-md: 8px;
  --r-lg: 14px;

  --sh-sm: 0 1px 2px rgba(30, 27, 22, 0.05), 0 2px 10px rgba(30, 27, 22, 0.04);
  --sh-md: 0 2px 6px rgba(30, 27, 22, 0.06), 0 20px 44px -22px rgba(30, 27, 22, 0.28);
  --sh-lg: 0 30px 70px -30px rgba(30, 27, 22, 0.45);

  --maxw: 1180px;
  --nav-h: 62px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 12px);
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* 纸面颗粒 + 暖光 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.55;
  background-image: radial-gradient(circle at 18% 8%, rgba(255, 252, 240, 0.9), transparent 42%),
    radial-gradient(circle at 82% 0%, rgba(226, 210, 180, 0.4), transparent 46%),
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='140' height='140' filter='url(%23n)' opacity='0.28'/%3E%3C/svg%3E");
  mix-blend-mode: multiply;
}

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

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

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

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

/* ---------- 版式容器 ---------- */
.wrap {
  width: min(var(--maxw), calc(100% - 48px));
  margin-inline: auto;
  position: relative;
  z-index: 1;
}

.kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.kicker::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--line-strong);
}

.sec-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 32px;
  margin-bottom: 44px;
}

.sec-title {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(28px, 3.4vw, 44px);
  line-height: 1.2;
  letter-spacing: -0.015em;
  margin: 12px 0 0;
}

.sec-title em {
  font-style: normal;
  color: var(--thread);
}

.sec-lead {
  max-width: 330px;
  font-size: 14px;
  color: var(--ink-2);
  line-height: 1.85;
  margin: 0;
}

.rule {
  height: 1px;
  background: var(--line);
  border: 0;
  margin: 0;
}

/* ---------- 顶栏 ---------- */
.topbar {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 40;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: rgba(246, 241, 228, 0.82);
  backdrop-filter: blur(14px) saturate(1.1);
  border-bottom: 1px solid rgba(216, 207, 186, 0.7);
}

.topbar-inner {
  width: min(var(--maxw), calc(100% - 48px));
  margin-inline: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--serif);
  font-size: 17px;
  letter-spacing: 0.14em;
}

.brand-mark {
  width: 22px;
  height: 22px;
  display: grid;
  place-items: center;
  border: 1px solid var(--ink);
  border-radius: 50%;
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0;
}

.nav {
  display: flex;
  gap: 30px;
  font-size: 13px;
  color: var(--ink-2);
}

.nav a {
  position: relative;
  padding: 4px 0;
  transition: color 0.25s ease;
}

.nav a:hover,
.nav a.is-active {
  color: var(--ink);
}

.nav a.is-active::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 1px;
  background: var(--thread);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  height: 46px;
  padding: 0 22px;
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  background: var(--ink);
  color: #fdfaf2;
  font-size: 14px;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: transform 0.18s ease, background 0.25s ease, box-shadow 0.25s ease;
}

.btn:hover {
  background: #332d24;
  box-shadow: 0 10px 24px -12px rgba(30, 27, 22, 0.6);
  transform: translateY(-1px);
}

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

.btn:focus-visible {
  outline: 2px solid var(--thread);
  outline-offset: 3px;
}

.btn:disabled {
  opacity: 0.55;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line-strong);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.6);
  box-shadow: none;
}

.btn-sm {
  height: 38px;
  padding: 0 16px;
  font-size: 13px;
}

/* 内联图标容器 */
.i {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: currentColor;
}

.btn-loading .btn-label::after,
.is-loading .btn-label::after {
  content: "";
  display: inline-block;
  width: 10px;
  height: 10px;
  margin-left: 8px;
  border: 1.5px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  vertical-align: -1px;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* =========================================================
   HERO
   ========================================================= */
.hero {
  padding: calc(var(--nav-h) + 62px) 0 72px;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.02fr 0.98fr;
  gap: 48px;
  align-items: center;
}

.hero h1 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(40px, 5.4vw, 68px);
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin: 18px 0 0;
  text-wrap: balance;
}

.hero h1 .num {
  font-family: var(--serif);
  font-style: italic;
  color: var(--thread);
}

.hero-lead {
  margin: 24px 0 0;
  max-width: 460px;
  font-size: 15px;
  line-height: 1.95;
  color: var(--ink-2);
}

.hero-lead b {
  font-weight: 600;
  color: var(--ink);
}

.hero-cta {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-top: 34px;
  flex-wrap: wrap;
}

.hero-meta {
  display: flex;
  gap: 34px;
  margin-top: 44px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.hero-meta div b {
  display: block;
  font-family: var(--serif);
  font-size: 26px;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.hero-meta div span {
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--ink-3);
  text-transform: uppercase;
}

/* ---------- 3D 笔记本（按实物结构建模：纸堆 + 可翻封面页 + 外露书脊） ---------- */
.rig {
  position: relative;
  --open: 180;         /* 0 = 合上，180 = 完全摊平 */
  --cover: #2c4c8a;
  --cover-ink: #f7f2e4;
  --thread: #e4e9f4;
  --archw: 2;
  --archh: 0;
  --lift: 0;           /* sin(开合角)：封面掀离桌面时的受光变化 */
  --shift: 0px;        /* 合上后整本书回正半页，视觉重心不往右跑 */
  --shadoww: 510px;    /* 书本投影宽度＝实际占地宽度 */
  --thick: 4px;        /* 封面页厚度 */
  --stack: 10px;       /* 内页纸堆厚度 */
}

.rig-scene {
  position: relative;
  height: 392px;
  perspective: 1800px;
  perspective-origin: 50% 38%;
}

.book-shadow {
  position: absolute;
  left: 50%;
  bottom: 34px;
  height: 74px;
  width: var(--shadoww, 510px);
  transform: translateX(-50%);
  background: radial-gradient(ellipse at 50% 52%, rgba(56, 42, 22, 0.34), rgba(56, 42, 22, 0) 70%);
  filter: blur(6px);
  pointer-events: none;
}

.book {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 500px;
  height: 336px;
  margin: -168px 0 0 -250px;
  transform-style: preserve-3d;
  transform: rotateX(46deg) rotateZ(-16deg) scale(var(--rigscale, 1));
}

/* 合上时书脊是铰链，投影少了左半页，整本书要向左补半页才保持居中 */
.book-pos {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transform: translateX(var(--shift, 0px));
}

/* 右半：书页堆 */
.block {
  position: absolute;
  left: 252px;
  top: 0;
  width: 248px;
  height: 336px;
  transform-style: preserve-3d;
}

/* 封板：比内页大一圈，压在纸堆底下，只露出一道深色书边 */
.board {
  position: absolute;
  inset: -7px -6px;
  border-radius: 5px;
  background: var(--cover);
  transform: translateZ(-2px);
  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.16), 0 2px 4px rgba(30, 27, 22, 0.18);
}

/* 叠纸侧边：180 页纸的厚度（等距视角下投影成一条带纸纹的窄边） */
.stack {
  position: absolute;
  left: 0;
  right: 0;
  top: 100%;
  height: var(--stack);
  border-radius: 0 0 5px 5px;
  background-image: repeating-linear-gradient(
      to bottom,
      rgba(252, 248, 238, 0.9) 0 1px,
      rgba(148, 136, 112, 0.5) 1px 2px
    ),
    linear-gradient(180deg, rgba(30, 27, 22, 0.1), rgba(30, 27, 22, 0.28));
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

/* 纸面 */
.paper {
  position: absolute;
  inset: 0;
  background-color: #fbf8ee;
  background-image: linear-gradient(
    100deg,
    rgba(30, 27, 22, 0.045),
    rgba(255, 255, 255, 0) 14%,
    rgba(255, 255, 255, 0) 84%,
    rgba(30, 27, 22, 0.05)
  );
  box-shadow: inset 0 0 0 1px rgba(30, 27, 22, 0.08), inset 0 1px 0 rgba(255, 255, 255, 0.9);
  overflow: hidden;
}

/* 右页：靠近书脊的一侧压出折痕阴影 */
.block .paper {
  border-radius: 3px 10px 10px 3px;
  box-shadow: inset 14px 0 20px -16px rgba(30, 27, 22, 0.42), inset 0 0 0 1px rgba(30, 27, 22, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.9);
}

/* 左半：一整叠封面页，绕书脊掀起；正角朝读者上方抬起，180° 时正好盖在右半页上 */
.leaf {
  position: absolute;
  left: 0;
  top: 0;
  width: 248px;
  height: 336px;
  transform-style: preserve-3d;
  transform-origin: 100% 50%;
  transform: translateZ(var(--thick)) rotateY(calc((180 - var(--open)) * 1deg));
}

.leaf-pos {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
}

/* 一页两面：朝上的内页 + 背面的封面，翻过去时不会出现镜像反字 */
.face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.face-front {
  transform: translateZ(0.02px);
  border-radius: 10px 3px 3px 10px;
  /* 外侧露出的封面板边 + 靠书脊的折痕阴影 */
  box-shadow: -5px 0 0 0 var(--cover), 0 5px 0 0 var(--cover),
    inset -14px 0 20px -16px rgba(30, 27, 22, 0.42), inset 0 0 0 1px rgba(30, 27, 22, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.9);
}

.face-back {
  inset: -6px;
  border-radius: 6px;
  background: var(--cover);
  transform: rotateY(180deg);
  transform-origin: 50% 50%;
  overflow: hidden;
  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.2);
}

/* 封面：书脊一侧压暗，上缘留高光 */
.face-back::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(0, 0, 0, 0.26), rgba(0, 0, 0, 0) 26%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.24), rgba(255, 255, 255, 0) 32%);
  pointer-events: none;
}

.cover {
  position: absolute;
  inset: 16px 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  color: var(--cover-ink);
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 3px;
}

.cover-mark {
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0.24em;
  opacity: 0.6;
}

.cover-name {
  font-family: var(--serif);
  font-size: 25px;
  letter-spacing: 0.16em;
}

.cover-rule {
  width: 34px;
  height: 1px;
  background: currentColor;
  opacity: 0.45;
}

.cover-sub {
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0.28em;
  opacity: 0.78;
}

.cover-foot {
  margin-top: 6px;
  font-size: 9px;
  letter-spacing: 0.1em;
  opacity: 0.5;
}

/* 页面立起来时受光变少，越接近竖直越暗 */
.leaf-sheen {
  position: absolute;
  inset: 0;
  border-radius: 10px 3px 3px 10px;
  background: linear-gradient(115deg, rgba(30, 27, 22, 0) 12%, rgba(30, 27, 22, 0.22) 92%);
  opacity: calc(var(--lift) * 0.5);
  pointer-events: none;
}

.rule-lines {
  position: absolute;
  left: 0;
  right: 0;
  top: 62px;
  bottom: 16px;
  background: repeating-linear-gradient(
    to bottom,
    transparent 0 23px,
    rgba(30, 27, 22, 0.15) 23px 24px
  );
}

.rule-margin {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 1px;
  background: rgba(44, 76, 138, 0.22);
}

.block .rule-margin {
  left: 46px;
}

.face-front .rule-margin {
  right: 46px;
}

.page-head {
  position: absolute;
  top: 22px;
  left: 24px;
  right: 24px;
  display: flex;
  justify-content: space-between;
  font-family: var(--mono);
  font-size: 8px;
  letter-spacing: 0.16em;
  color: rgba(30, 27, 22, 0.32);
}

.page-head .dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: rgba(30, 27, 22, 0.22);
  align-self: center;
}

.page-foot {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 13px;
  text-align: center;
  font-family: var(--mono);
  font-size: 8px;
  letter-spacing: 0.2em;
  color: rgba(30, 27, 22, 0.26);
}

/* 书脊：夹在两页之间，合上时被封面盖住 */
.spine {
  position: absolute;
  left: 248px;
  top: 0;
  width: 8px;
  height: 336px;
  transform-style: preserve-3d;
  transform: translateZ(1px);
}

.stitch {
  position: absolute;
  top: 2px;
  bottom: 2px;
  left: 2.5px;
  width: 3px;
  border-radius: 2px;
  background: repeating-linear-gradient(
    to bottom,
    var(--thread) 0 9px,
    rgba(0, 0, 0, 0) 9px 15px
  );
  box-shadow: 0 0 0 0.5px rgba(0, 0, 0, 0.08);
  transition: opacity 0.25s ease;
}

.ridge {
  position: absolute;
  left: 50%;
  top: -5px;
  bottom: -5px;
  width: calc(var(--archw) * 1px);
  transform: translateX(-50%);
  border-radius: 50% / 14px;
  background: linear-gradient(
    90deg,
    rgba(30, 27, 22, 0.34),
    rgba(255, 250, 236, 0.96) 42%,
    rgba(255, 250, 236, 0.9) 58%,
    rgba(30, 27, 22, 0.42)
  );
  box-shadow: 0 12px 20px rgba(30, 27, 22, 0.26);
  opacity: var(--archo, 0);
  transition: width 0.15s linear, opacity 0.15s linear;
}

.rig[data-binding="flat"] .ridge {
  display: none;
}

.rig[data-binding="glue"] .stitch {
  opacity: 0;
}

/* 状态角标 */
.callout {
  position: absolute;
  top: 10px;
  left: 50%;
  transform: translateX(-50%);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 28px;
  padding: 0 14px;
  border-radius: 20px;
  background: rgba(252, 249, 241, 0.94);
  border: 1px solid var(--line);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--thread);
  box-shadow: var(--sh-sm);
  white-space: nowrap;
  transition: color 0.25s ease;
}

.callout::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: currentColor;
}

.callout.warn {
  color: var(--ochre);
}

/* 控制面板 */
.rig-controls {
  margin-top: 4px;
  padding: 18px 20px 20px;
  background: rgba(252, 249, 241, 0.86);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  box-shadow: var(--sh-sm);
}

.seg {
  display: inline-flex;
  padding: 3px;
  background: var(--surface-2);
  border-radius: 6px;
  gap: 2px;
}

.seg-btn {
  border: 0;
  background: transparent;
  padding: 7px 16px;
  font-size: 12.5px;
  color: var(--ink-2);
  border-radius: 4px;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease;
}

.seg-btn:hover {
  color: var(--ink);
}

.seg-btn.is-active {
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 1px 3px rgba(30, 27, 22, 0.14);
}

.slider-row {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 14px;
  margin-top: 16px;
  font-size: 12.5px;
  color: var(--ink-3);
}

.slider-row output {
  font-family: var(--mono);
  color: var(--ink);
  font-size: 12.5px;
  min-width: 42px;
  text-align: right;
}

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 22px;
  background: transparent;
  cursor: ew-resize;
}

input[type="range"]::-webkit-slider-runnable-track {
  height: 3px;
  background: linear-gradient(90deg, var(--thread), var(--line-strong));
  border-radius: 2px;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  margin-top: -6.5px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--ink);
  box-shadow: 0 2px 6px rgba(30, 27, 22, 0.28);
}

input[type="range"]::-moz-range-track {
  height: 3px;
  background: var(--line-strong);
  border-radius: 2px;
}

input[type="range"]::-moz-range-thumb {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--ink);
}

input[type="range"]:focus-visible {
  outline: 2px solid var(--thread);
  outline-offset: 4px;
  border-radius: 4px;
}

.readout {
  display: flex;
  gap: 28px;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px dashed var(--line);
}

.readout div {
  display: flex;
  align-items: baseline;
  gap: 6px;
}

.readout b {
  font-family: var(--serif);
  font-size: 21px;
  font-weight: 400;
  letter-spacing: -0.01em;
}

.readout span {
  font-size: 11px;
  color: var(--ink-3);
}

/* =========================================================
   结构解剖
   ========================================================= */
.section {
  padding: 92px 0;
  border-top: 1px solid var(--line);
  position: relative;
  z-index: 1;
}

.anatomy-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 56px;
  align-items: start;
}

.anatomy-list {
  display: grid;
  gap: 0;
}

.anatomy-item {
  display: grid;
  grid-template-columns: 62px 1fr;
  gap: 18px;
  padding: 26px 0;
  border-bottom: 1px solid var(--line);
}

.anatomy-item:first-child {
  padding-top: 0;
}

.anatomy-no {
  font-family: var(--serif);
  font-style: italic;
  font-size: 30px;
  line-height: 1;
  color: var(--thread);
  opacity: 0.75;
}

.anatomy-item h3 {
  margin: 0 0 8px;
  font-size: 16.5px;
  font-weight: 600;
  letter-spacing: 0.01em;
}

.anatomy-item p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.9;
  color: var(--ink-2);
}

.proof {
  position: sticky;
  top: calc(var(--nav-h) + 24px);
}

.proof-frame {
  position: relative;
  padding: 12px;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--sh-md);
  transform: rotate(-1.2deg);
}

.proof-frame img {
  width: 100%;
  filter: saturate(0.96) contrast(1.02);
}

.proof-cap {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin-top: 14px;
  font-size: 12px;
  line-height: 1.75;
  color: var(--ink-3);
}

.proof-cap .pin {
  margin-top: 3px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--ochre);
  flex: none;
}

.proof-tag {
  position: absolute;
  top: -13px;
  left: 18px;
  background: var(--ochre);
  color: #fdf7ef;
  font-size: 11px;
  letter-spacing: 0.1em;
  padding: 4px 10px;
  transform: rotate(1.5deg);
}

/* =========================================================
   特性
   ========================================================= */
.features {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.feature {
  background: var(--surface);
  padding: 30px 26px 34px;
  transition: background 0.25s ease;
}

.feature:hover {
  background: #fffdf6;
}

.feature .ic {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  color: var(--thread);
  margin-bottom: 22px;
}

.feature h3 {
  margin: 0 0 10px;
  font-size: 16px;
  font-weight: 600;
}

.feature p {
  margin: 0;
  font-size: 13px;
  line-height: 1.85;
  color: var(--ink-2);
}

/* =========================================================
   对比表
   ========================================================= */
.compare-wrap {
  border: 1px solid var(--line);
  background: var(--surface);
  box-shadow: var(--sh-sm);
  overflow: hidden;
}

.compare {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.compare th,
.compare td {
  padding: 17px 24px;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: middle;
}

.compare thead th {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-3);
  font-weight: 400;
  background: var(--surface-2);
}

.compare thead th.hl {
  color: var(--thread);
  background: var(--thread-soft);
}

.compare td:first-child {
  color: var(--ink-2);
  font-size: 13px;
  width: 30%;
}

.compare td.glue {
  color: var(--ink-3);
}

.compare td.flat {
  color: var(--ink);
  font-weight: 500;
  background: rgba(227, 233, 245, 0.4);
}

.compare tbody tr:last-child td {
  border-bottom: 0;
}

.compare tbody tr:hover td {
  background: #fffdf7;
}

.compare tbody tr:hover td.flat {
  background: rgba(227, 233, 245, 0.7);
}

/* =========================================================
   规格 & 配色
   ========================================================= */
.spec-grid {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  gap: 56px;
}

.spec-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.spec-item {
  background: var(--surface);
  padding: 20px 22px;
}

.spec-item .k {
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
  text-transform: uppercase;
}

.spec-item .v {
  margin-top: 4px;
  font-size: 15px;
  font-family: var(--serif);
  letter-spacing: 0.01em;
}

.color-panel {
  padding: 26px;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--sh-sm);
}

.color-panel h4 {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
  text-transform: uppercase;
  font-weight: 400;
}

.color-name {
  font-family: var(--serif);
  font-size: 28px;
  margin: 6px 0 18px;
  letter-spacing: -0.01em;
}

.swatches {
  display: flex;
  gap: 12px;
}

.swatch {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 2px solid transparent;
  cursor: pointer;
  position: relative;
  transition: transform 0.18s ease, border-color 0.2s ease;
}

.swatch:hover {
  transform: translateY(-2px);
}

.swatch.is-active {
  border-color: var(--ink);
  box-shadow: 0 0 0 3px var(--surface) inset;
}

.swatch:focus-visible {
  outline: 2px solid var(--thread);
  outline-offset: 3px;
}

.color-note {
  margin-top: 20px;
  font-size: 12.5px;
  line-height: 1.9;
  color: var(--ink-2);
  border-top: 1px dashed var(--line);
  padding-top: 14px;
}

/* =========================================================
   宣传图
   ========================================================= */
.poster-section {
  background: linear-gradient(180deg, rgba(237, 228, 209, 0.4), rgba(246, 241, 228, 0));
}

.poster-layout {
  display: grid;
  grid-template-columns: 0.82fr 1.18fr;
  gap: 52px;
  align-items: center;
}

.poster-copy h2 {
  font-family: var(--serif);
  font-size: clamp(26px, 3vw, 38px);
  font-weight: 400;
  line-height: 1.3;
  margin: 14px 0 16px;
  letter-spacing: -0.015em;
}

.poster-copy p {
  font-size: 14px;
  line-height: 1.9;
  color: var(--ink-2);
  margin: 0 0 26px;
}

.poster-meta {
  display: grid;
  gap: 10px;
  margin-bottom: 26px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-3);
}

.poster-meta span {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px dashed var(--line);
  padding-bottom: 8px;
}

.poster-meta i {
  font-style: normal;
}

.poster-meta span:first-child i:last-child {
  color: var(--ink);
}

.poster-frame {
  position: relative;
  padding: 14px;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--sh-lg);
  transform: rotate(1deg);
}

.poster-frame img {
  width: 100%;
}

.poster-frame::after {
  content: "LAYFLAT · KV 01";
  position: absolute;
  right: 20px;
  bottom: 18px;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: rgba(255, 255, 255, 0.85);
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.4);
}

/* =========================================================
   预约
   ========================================================= */
.preorder {
  display: grid;
  grid-template-columns: 0.92fr 1.08fr;
  gap: 0;
  border: 1px solid var(--line);
  background: var(--surface);
  box-shadow: var(--sh-md);
}

.preorder-info {
  padding: 46px 44px;
  background: var(--ink);
  color: #f4efe2;
  position: relative;
  overflow: hidden;
}

.preorder-info::after {
  content: "180°";
  position: absolute;
  right: -14px;
  bottom: -46px;
  font-family: var(--serif);
  font-style: italic;
  font-size: 150px;
  line-height: 1;
  color: rgba(255, 255, 255, 0.06);
  pointer-events: none;
}

.preorder-info .kicker {
  color: rgba(244, 239, 226, 0.55);
}

.preorder-info .kicker::before {
  background: rgba(244, 239, 226, 0.3);
}

.preorder-info h2 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: 34px;
  line-height: 1.3;
  margin: 16px 0 14px;
  letter-spacing: -0.015em;
}

.preorder-info p {
  font-size: 13.5px;
  line-height: 1.9;
  color: rgba(244, 239, 226, 0.72);
  margin: 0 0 28px;
  max-width: 320px;
}

.price-row {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.price-now {
  font-family: var(--serif);
  font-size: 46px;
  letter-spacing: -0.02em;
}

.price-now small {
  font-size: 18px;
  margin-right: 2px;
}

.price-was {
  font-size: 13px;
  color: rgba(244, 239, 226, 0.45);
  text-decoration: line-through;
}

.stock {
  margin-top: 26px;
  font-size: 11.5px;
  color: rgba(244, 239, 226, 0.6);
  font-family: var(--mono);
}

.stock-bar {
  margin-top: 8px;
  height: 4px;
  background: rgba(255, 255, 255, 0.14);
  border-radius: 2px;
  overflow: hidden;
}

.stock-bar i {
  display: block;
  height: 100%;
  width: 48.3%;
  background: var(--ochre);
  transition: width 0.6s ease;
}

.preorder-form {
  padding: 46px 44px;
}

.form-title {
  font-size: 15px;
  font-weight: 600;
  margin: 0 0 4px;
}

.form-sub {
  font-size: 12.5px;
  color: var(--ink-3);
  margin: 0 0 24px;
}

.field {
  margin-bottom: 18px;
}

.field label {
  display: block;
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--ink-3);
  text-transform: uppercase;
  margin-bottom: 8px;
}

.field input {
  width: 100%;
  height: 48px;
  padding: 0 16px;
  background: var(--paper);
  border: 1px solid var(--line-strong);
  border-radius: var(--r-sm);
  font-size: 14px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.field input::placeholder {
  color: var(--ink-3);
}

.field input:focus {
  outline: none;
  border-color: var(--thread);
  box-shadow: 0 0 0 3px rgba(44, 76, 138, 0.12);
}

.field input.is-error {
  border-color: var(--ochre);
  box-shadow: 0 0 0 3px rgba(176, 96, 58, 0.12);
}

.qty-row {
  display: flex;
  align-items: center;
  gap: 0;
  border: 1px solid var(--line-strong);
  border-radius: var(--r-sm);
  width: fit-content;
  overflow: hidden;
}

.qty-btn {
  width: 44px;
  height: 38px;
  border: 0;
  background: var(--surface-2);
  cursor: pointer;
  font-size: 16px;
  color: var(--ink-2);
  transition: background 0.2s ease;
}

.qty-btn:hover {
  background: var(--paper-2);
  color: var(--ink);
}

.qty-btn:focus-visible {
  outline: 2px solid var(--thread);
  outline-offset: -2px;
}

.qty-row input {
  width: 54px;
  height: 38px;
  border: 0;
  border-left: 1px solid var(--line);
  border-right: 1px solid var(--line);
  text-align: center;
  font-family: var(--mono);
  background: var(--surface);
  border-radius: 0;
}

.qty-row input:focus {
  outline: none;
  box-shadow: none;
}

.form-msg {
  min-height: 20px;
  font-size: 12.5px;
  color: var(--ochre);
  margin: 2px 0 6px;
}

.submit {
  width: 100%;
  height: 50px;
  margin-top: 6px;
}

.form-foot {
  margin-top: 14px;
  font-size: 11.5px;
  color: var(--ink-3);
  line-height: 1.8;
}

/* 成功态 */
.success-card {
  padding: 8px 0;
}

.success-card .check {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--ok);
  display: grid;
  place-items: center;
  color: var(--ok);
  margin-bottom: 18px;
}

.success-card h3 {
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 400;
  margin: 0 0 6px;
}

.success-card p {
  font-size: 12.5px;
  color: var(--ink-3);
  margin: 0 0 20px;
}

.order-no {
  font-family: var(--mono);
  font-size: 20px;
  letter-spacing: 0.08em;
  padding: 14px 16px;
  background: var(--paper);
  border: 1px dashed var(--line-strong);
  border-radius: var(--r-sm);
  margin-bottom: 14px;
}

.order-line {
  display: flex;
  justify-content: space-between;
  font-size: 12.5px;
  color: var(--ink-2);
  padding: 7px 0;
  border-bottom: 1px solid var(--line);
}

.order-line span:last-child {
  color: var(--ink);
}

.success-note {
  margin-top: 18px;
  font-size: 12px;
  color: var(--ink-3);
  line-height: 1.8;
}

/* =========================================================
   口碑 / 页脚
   ========================================================= */
.quotes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.quote {
  background: var(--surface);
  padding: 28px 26px;
}

.quote .tag {
  display: inline-block;
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--thread);
  border: 1px solid rgba(44, 76, 138, 0.3);
  border-radius: 20px;
  padding: 2px 9px;
  margin-bottom: 16px;
}

.quote p {
  font-family: var(--serif);
  font-size: 19px;
  line-height: 1.6;
  margin: 0 0 14px;
  letter-spacing: -0.005em;
}

.quote .who {
  font-size: 12px;
  color: var(--ink-3);
}

footer {
  padding: 54px 0 46px;
  border-top: 1px solid var(--line);
  background: rgba(237, 228, 209, 0.35);
}

.foot-grid {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 32px;
  flex-wrap: wrap;
}

.foot-brand {
  font-family: var(--serif);
  font-size: 24px;
  letter-spacing: 0.14em;
}

.foot-brand small {
  display: block;
  font-family: var(--sans);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
  margin-top: 6px;
}

.foot-note {
  font-size: 11.5px;
  color: var(--ink-3);
  line-height: 1.9;
  max-width: 360px;
}

/* ---------- toast ---------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: 34px;
  transform: translate(-50%, 18px);
  z-index: 60;
  background: var(--ink);
  color: #f7f1e4;
  font-size: 13px;
  padding: 11px 20px;
  border-radius: 4px;
  box-shadow: 0 18px 40px -16px rgba(0, 0, 0, 0.5);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.28s ease, transform 0.28s ease;
}

.toast.show {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* ---------- 入场动画 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.7s cubic-bezier(0.22, 1, 0.36, 1), transform 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}

[data-reveal].in {
  opacity: 1;
  transform: none;
}

.hero-copy > * {
  animation: rise 0.9s cubic-bezier(0.22, 1, 0.36, 1) both;
}

.hero-copy > *:nth-child(1) { animation-delay: 0.06s; }
.hero-copy > *:nth-child(2) { animation-delay: 0.14s; }
.hero-copy > *:nth-child(3) { animation-delay: 0.22s; }
.hero-copy > *:nth-child(4) { animation-delay: 0.3s; }
.hero-copy > *:nth-child(5) { animation-delay: 0.38s; }

.hero-visual {
  animation: rise 1s cubic-bezier(0.22, 1, 0.36, 1) 0.18s both;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(22px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  .rig {
    max-width: 560px;
    margin-inline: auto;
  }
  .anatomy-grid,
  .spec-grid,
  .poster-layout {
    grid-template-columns: 1fr;
    gap: 36px;
  }
  .proof {
    position: static;
    max-width: 460px;
  }
  .features {
    grid-template-columns: repeat(2, 1fr);
  }
  .preorder {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 760px) {
  :root {
    --nav-h: 56px;
  }
  .wrap {
    width: calc(100% - 32px);
  }
  .topbar-inner {
    width: calc(100% - 32px);
  }
  .nav {
    display: none;
  }
  .hero {
    padding-top: calc(var(--nav-h) + 36px);
  }
  .hero-meta {
    gap: 24px;
    flex-wrap: wrap;
  }
  .rig {
    --rigscale: 0.7;
  }
  .rig-scene {
    height: 300px;
  }
  .sec-head {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
    margin-bottom: 32px;
  }
  .features,
  .quotes {
    grid-template-columns: 1fr;
  }
  .spec-list {
    grid-template-columns: 1fr;
  }
  .anatomy-item {
    grid-template-columns: 44px 1fr;
  }
  .compare th,
  .compare td {
    padding: 13px 14px;
    font-size: 12.5px;
  }
  .compare td:first-child {
    width: 34%;
    font-size: 12px;
  }
  .preorder-info,
  .preorder-form {
    padding: 32px 24px;
  }
  .section {
    padding: 62px 0;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 38px;
  }
  .rig {
    --rigscale: 0.55;
  }
  .rig-scene {
    height: 250px;
  }
  .rig-controls {
    padding: 14px 16px 16px;
  }
  .readout {
    gap: 18px;
  }
  .quote p {
    font-size: 17px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
  [data-reveal] {
    opacity: 1;
    transform: none;
  }
}