/* =========================================================
   前端自习室 · 起始主页
   设计系统：learn.css 暖白教学风（纸本 + 赭橙 accent）
   ========================================================= */

:root {
  --bg: #FAF5EC;
  --paper: #FFFDF8;
  --paper-2: #FDF8EF;
  --ink: #2B251D;
  --ink-2: #574D40;
  --ink-3: #8B7E6C;
  --line: #EAE0CD;
  --line-2: #DFD2BA;

  --accent: #B8552F;
  --accent-deep: #9A4423;
  --accent-soft: rgba(184, 85, 47, 0.08);
  --accent-softer: rgba(184, 85, 47, 0.045);
  --accent-glow: rgba(184, 85, 47, 0.18);

  --green: #5F7F52;
  --green-soft: rgba(95, 127, 82, 0.10);
  --amber: #B07A2A;
  --amber-soft: rgba(176, 122, 42, 0.12);

  /* 交互美学强调色 */
  --teal: #1F6F5C;
  --teal-soft: rgba(31, 111, 92, 0.10);
  --gold: #C9A22E;
  --gold-soft: rgba(201, 162, 46, 0.12);
  --violet: #6B4F8A;
  --violet-soft: rgba(107, 79, 138, 0.10);
  --coral: #E8A87C;

  --font-ui: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-code: "JetBrains Mono", "Cascadia Code", Consolas, "Courier New", monospace;

  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-spring: cubic-bezier(0.34, 1.4, 0.44, 1);
  --ease-inout: cubic-bezier(0.65, 0, 0.35, 1);

  --nav-h: 64px;
  --max: 1120px;
  --r-card: 14px;
  --r-lg: 22px;
  --r-md: 12px;

  --shadow-1: 0 2px 10px rgba(122, 88, 48, 0.06);
  --shadow-2: 0 10px 34px rgba(122, 88, 48, 0.12);
  --shadow-pop: 0 18px 60px rgba(96, 66, 32, 0.18);

  --scroll: 0;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: auto;
  -webkit-font-smoothing: antialiased;
}

html.reduced {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-ui);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.75;
  overflow-x: clip;
  min-height: 100vh;
}

body.is-hovering {
  cursor: none;
}

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

ul, ol { list-style: none; }

code {
  font-family: var(--font-code);
  font-size: 0.88em;
  color: var(--accent-deep);
  background: var(--accent-soft);
  padding: 0.12em 0.42em;
  border-radius: 6px;
}

::selection {
  background: rgba(184, 85, 47, 0.22);
  color: var(--ink);
}

/* ---------- 光标 ---------- */
.cursor {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 10000;
  pointer-events: none;
  mix-blend-mode: multiply;
}

.cursor-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  transform: translate(-50%, -50%);
}

.cursor-ring {
  position: absolute;
  top: 0;
  left: 0;
  width: 32px;
  height: 32px;
  border: 1.5px solid rgba(184, 85, 47, 0.45);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.35s var(--ease-out), height 0.35s var(--ease-out),
    border-color 0.3s, opacity 0.3s;
}

.cursor.is-hover .cursor-ring {
  width: 56px;
  height: 56px;
  border-color: var(--accent);
}

.cursor.is-down .cursor-ring {
  width: 20px;
  height: 20px;
}

@media (hover: none), (pointer: coarse) {
  .cursor { display: none; }
  body.is-hovering { cursor: auto; }
}

/* ---------- 顶栏 ---------- */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 0 clamp(18px, 4vw, 40px);
  background: rgba(250, 245, 236, 0.82);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.35s, background 0.35s;
}

.site-nav.is-scrolled {
  border-bottom-color: var(--line);
  background: rgba(255, 253, 248, 0.92);
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  min-width: 0;
}

.brand-mark {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: 17px;
  color: #FFF7EF;
  background: linear-gradient(135deg, var(--accent), var(--accent-deep));
  box-shadow: 0 6px 18px rgba(154, 68, 35, 0.28);
  flex: none;
}

.brand-text {
  font-weight: 800;
  font-size: 14.5px;
  letter-spacing: 0.02em;
  line-height: 1.15;
  display: flex;
  flex-direction: column;
}

.brand-text small {
  font-family: var(--font-code);
  font-size: 9px;
  font-weight: 500;
  letter-spacing: 0.16em;
  color: var(--ink-3);
}

.nav-links {
  display: flex;
  gap: 26px;
  font-size: 13.5px;
  font-weight: 600;
  color: var(--ink-2);
}

.nav-links a {
  position: relative;
  padding: 6px 0;
  transition: color 0.25s var(--ease-out);
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 1.5px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.35s var(--ease-out);
}

.nav-links a:hover { color: var(--accent-deep); }
.nav-links a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 700;
  padding: 9px 16px;
  border-radius: 999px;
  border: 1px solid var(--line-2);
  background: var(--paper);
  color: var(--ink);
  transition: all 0.35s var(--ease-out);
}

.nav-cta:hover {
  border-color: var(--accent);
  color: var(--accent-deep);
  box-shadow: var(--shadow-1);
}

.nav-cta .arrow {
  transition: transform 0.35s var(--ease-out);
}

.nav-cta:hover .arrow { transform: translateX(3px); }

@media (max-width: 820px) {
  .nav-links { display: none; }
}

/* ---------- 分段进度轨 ---------- */
.seg-rail {
  position: fixed;
  top: 50%;
  right: clamp(10px, 2vw, 24px);
  transform: translateY(-50%);
  z-index: 90;
  display: flex;
  align-items: stretch;
  gap: 10px;
  height: min(48vh, 380px);
}

.seg-track {
  width: 2px;
  background: var(--line-2);
  border-radius: 2px;
  position: relative;
  overflow: hidden;
}

.seg-fill {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: calc(var(--scroll) * 100%);
  background: linear-gradient(180deg, var(--accent), var(--accent-deep));
  border-radius: 2px;
}

.seg-list {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  font-family: var(--font-code);
  font-size: 10px;
  letter-spacing: 0.1em;
}

.seg-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--ink-3);
  cursor: pointer;
  transition: color 0.3s;
  white-space: nowrap;
}

.seg-list li i {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  border: 1.5px solid var(--ink-3);
  background: transparent;
  transition: all 0.35s var(--ease-out);
  flex: none;
}

.seg-list li span {
  opacity: 0;
  transform: translateX(6px);
  transition: opacity 0.3s, transform 0.35s var(--ease-out);
}

.seg-list li:hover span,
.seg-list li.is-active span {
  opacity: 1;
  transform: none;
}

.seg-list li.is-active { color: var(--accent-deep); }
.seg-list li.is-active i {
  border-color: var(--accent);
  background: var(--accent);
  transform: scale(1.15);
}

@media (max-width: 720px) {
  .seg-rail { display: none; }
}

/* ---------- 通用 ---------- */
.sec-kicker {
  font-family: var(--font-code);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--accent);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.sec-kicker::before {
  content: "";
  width: 24px;
  height: 1.5px;
  background: var(--accent);
}

.sec-title {
  font-size: clamp(32px, 5vw, 52px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 14px;
  color: var(--ink);
}

.sec-desc {
  font-size: clamp(14.5px, 1.4vw, 16.5px);
  color: var(--ink-2);
  max-width: 48ch;
  line-height: 1.85;
}

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 26px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.02em;
  border: 1px solid transparent;
  overflow: hidden;
  isolation: isolate;
  transition: transform 0.45s var(--ease-out), box-shadow 0.45s var(--ease-out),
    border-color 0.3s, background 0.3s, color 0.3s;
  will-change: transform;
}

.btn-lg {
  padding: 16px 32px;
  font-size: 15.5px;
}

.btn-primary {
  color: #FFF7EF;
  background: linear-gradient(135deg, var(--accent), var(--accent-deep));
  box-shadow: 0 10px 28px rgba(154, 68, 35, 0.28);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 16px 40px rgba(154, 68, 35, 0.38);
}

.btn-primary .btn-glow {
  position: absolute;
  inset: 0;
  background: radial-gradient(110px 50px at var(--mx, 50%) var(--my, 50%),
    rgba(255, 255, 255, 0.28), transparent 70%);
  opacity: 0;
  transition: opacity 0.35s;
  z-index: -1;
}

.btn-primary:hover .btn-glow { opacity: 1; }

.btn-ghost {
  color: var(--ink);
  border-color: var(--line-2);
  background: var(--paper);
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent-deep);
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(184, 85, 47, 0.15);
}

/* 交互光晕条 */
.hero::after,
.cta-sec::before {
  content: "";
  position: absolute;
  left: 8%;
  right: 8%;
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(
    90deg,
    var(--accent),
    var(--coral),
    var(--gold),
    var(--teal),
    var(--violet)
  );
  opacity: 0.55;
  pointer-events: none;
}

.hero::after { bottom: 28px; }
.cta-sec::before { top: 40px; }

.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.85s var(--ease-out), transform 0.85s var(--ease-out);
  transition-delay: var(--d, 0s);
}

.reveal.is-in {
  opacity: 1;
  transform: none;
}

html.reduced .reveal {
  opacity: 1;
  transform: none;
  transition: none;
}

.word {
  display: inline-block;
  overflow: hidden;
  vertical-align: bottom;
  padding-bottom: 0.08em;
}

.word .char {
  display: inline-block;
  transform: translateY(110%) rotate(3deg);
  opacity: 0;
  transition: transform 0.9s var(--ease-out), opacity 0.65s ease;
  transition-delay: var(--ci, 0s);
}

.is-in .char,
.hero.is-ready .char {
  transform: none;
  opacity: 1;
}

html.reduced .word .char {
  transform: none;
  opacity: 1;
  transition: none;
}

/* =========================================================
   HERO
   ========================================================= */
.hero {
  position: relative;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  align-items: center;
  padding: calc(var(--nav-h) + 36px) clamp(20px, 5vw, 56px) 88px;
  overflow: hidden;
  background:
    radial-gradient(ellipse 70% 55% at 85% 15%, rgba(184, 85, 47, 0.10), transparent 60%),
    radial-gradient(ellipse 50% 40% at 10% 85%, rgba(95, 127, 82, 0.08), transparent 55%),
    var(--bg);
}

.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(60px);
  opacity: 0.55;
}

.orb-a {
  width: min(50vw, 520px);
  height: min(50vw, 520px);
  top: -8%;
  right: -6%;
  background: radial-gradient(circle, rgba(184, 85, 47, 0.28), transparent 70%);
}

.orb-b {
  width: min(40vw, 400px);
  height: min(40vw, 400px);
  bottom: -4%;
  left: -8%;
  background: radial-gradient(circle, rgba(95, 127, 82, 0.16), transparent 70%);
}

.grid-lines {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(43, 37, 29, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(43, 37, 29, 0.04) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(ellipse 75% 65% at 50% 40%, #000 15%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 75% 65% at 50% 40%, #000 15%, transparent 75%);
}

.hero-inner {
  position: relative;
  z-index: 2;
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
}

.hero-kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-code);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--ink-2);
  padding: 7px 13px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 253, 248, 0.8);
  margin-bottom: 26px;
}

.hero-kicker .tick {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 0 rgba(184, 85, 47, 0.5);
  animation: pulse 2.2s ease-out infinite;
}

@keyframes pulse {
  0% { box-shadow: 0 0 0 0 rgba(184, 85, 47, 0.45); }
  70% { box-shadow: 0 0 0 10px rgba(184, 85, 47, 0); }
  100% { box-shadow: 0 0 0 0 rgba(184, 85, 47, 0); }
}

.hero-title {
  font-size: clamp(52px, 10vw, 104px);
  font-weight: 800;
  letter-spacing: -0.045em;
  line-height: 1.02;
  margin-bottom: 24px;
  color: var(--ink);
}

.hero-title .line { display: block; }

.hero-title .accent .char {
  background: linear-gradient(135deg, var(--accent), var(--accent-deep));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-lead {
  font-size: clamp(15.5px, 1.6vw, 18px);
  color: var(--ink-2);
  max-width: 36ch;
  line-height: 1.9;
  margin-bottom: 32px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 48px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 28px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  max-width: 520px;
}

.hero-meta div {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.hero-meta b {
  font-family: var(--font-code);
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ink);
  line-height: 1.1;
}

.hero-meta span {
  font-size: 12px;
  color: var(--ink-3);
  letter-spacing: 0.08em;
}

.scroll-hint {
  position: absolute;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--ink-3);
  z-index: 3;
}

.mouse {
  width: 20px;
  height: 32px;
  border: 1.5px solid var(--ink-3);
  border-radius: 11px;
  position: relative;
}

.mouse i {
  position: absolute;
  top: 6px;
  left: 50%;
  width: 3px;
  height: 7px;
  margin-left: -1.5px;
  border-radius: 2px;
  background: var(--accent);
  animation: wheel 1.8s var(--ease-inout) infinite;
}

@keyframes wheel {
  0% { opacity: 1; transform: translateY(0); }
  100% { opacity: 0; transform: translateY(11px); }
}

.hint-text {
  font-family: var(--font-code);
  font-size: 10px;
  letter-spacing: 0.24em;
}

/* =========================================================
   交叠 STACK
   ========================================================= */
.stack-sec {
  position: relative;
  padding: 88px 0 12vh;
  max-width: var(--max);
  margin: 0 auto;
  width: 100%;
  padding-left: clamp(20px, 5vw, 56px);
  padding-right: clamp(20px, 5vw, 56px);
}

.stack-intro {
  margin-bottom: 40px;
  max-width: 560px;
}

.stack-stage {
  display: block;
  padding-bottom: 8vh;
  isolation: isolate;
}

.stack-card + .stack-card {
  margin-top: 18px;
}

.stack-card {
  position: sticky;
  top: calc(var(--nav-h) + 2vh);
  min-height: min(68vh, 560px);
  border-radius: var(--r-lg);
  border: 1px solid var(--line);
  background: var(--paper);
  overflow: hidden;
  box-shadow: var(--shadow-2);
  --stack-p: 0;
  z-index: 1;
  /* 前者模糊 · 当者色深 · 后者色淡 */
  transition: background 0.45s var(--ease-out), border-color 0.45s, box-shadow 0.45s;
}

/* 后卡压前卡：同一 sticky 顶，z-index 严格递增 */
.stack-card:nth-child(1) { z-index: 1; }
.stack-card:nth-child(2) { z-index: 2; }
.stack-card:nth-child(3) { z-index: 3; }
.stack-card:nth-child(4) { z-index: 4; }
.stack-card:nth-child(5) { z-index: 5; }
.stack-card:nth-child(6) { z-index: 6; }
.stack-card:nth-child(7) { z-index: 7; }
.stack-card:nth-child(8) { z-index: 8; }
.stack-card:nth-child(n+9) { z-index: 9; }

.stack-card-inner {
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  width: 100%;
  min-width: 0;
  min-height: inherit;
  transform-origin: center top;
  transition: filter 0.4s var(--ease-out), transform 0.4s var(--ease-out),
    opacity 0.4s var(--ease-out);
}

/* 课时交叠卡：内容完整展示，不裁切、不错位 */
.stack-card.lesson-card {
  min-height: 0;
  overflow: visible;
  border-radius: var(--r-lg);
}

.stack-card.lesson-card .stack-card-inner {
  display: block;
  width: 100%;
  min-height: 0;
  box-sizing: border-box;
}

.stack-card.lesson-card .card-body {
  padding: clamp(22px, 3vw, 32px) clamp(22px, 3vw, 36px);
  justify-content: flex-start;
  gap: 10px;
  background: transparent;
}

.stack-card.lesson-card .card-body p {
  max-width: 62ch;
  margin: 0;
  line-break: strict;
  word-break: keep-all;
  overflow-wrap: break-word;
}

.stack-card.lesson-card .card-tags:empty {
  display: none;
}

.stack-card.lesson-card .card-link {
  margin-top: 6px;
  align-self: flex-start;
}

/* 缩放模糊时不要裁掉圆角内容 */
.stack-card.lesson-card[data-state="past"] .stack-card-inner {
  overflow: visible;
}

/* 后者（未盖到）：保持浅色 */
.stack-card[data-state="future"] {
  background: var(--paper);
  border-color: var(--line);
  box-shadow: 0 10px 28px rgba(122, 88, 48, 0.08);
}

.stack-card[data-state="future"] .stack-card-inner {
  filter: none;
  opacity: 1;
  transform: none;
}

/* 当者（网页中心区域）：颜色压深 */
.stack-card[data-state="current"] {
  background: linear-gradient(
    165deg,
    #fffaf2 0%,
    #f3e7d2 52%,
    #e8d5b5 100%
  );
  border-color: rgba(184, 85, 47, 0.28);
  box-shadow:
    0 28px 72px rgba(96, 66, 32, 0.22),
    0 6px 18px rgba(184, 85, 47, 0.12);
}

.stack-card[data-state="current"]::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(
    180deg,
    rgba(184, 85, 47, 0.06),
    rgba(122, 88, 48, 0.1)
  );
  border-radius: inherit;
}

.stack-card[data-state="current"] .card-num,
.stack-card[data-state="current"] .card-body h3 {
  color: var(--accent-deep);
}

.stack-card[data-state="current"] .card-body p {
  color: var(--ink);
}

.stack-card[data-state="current"] .stack-card-inner {
  filter: none;
  opacity: 1;
  transform: none;
}

/* 前者（正被盖住）：高斯模糊 + 压暗 */
.stack-card[data-state="past"] {
  background: var(--paper-2);
  border-color: transparent;
  box-shadow: 0 8px 24px rgba(96, 66, 32, 0.08);
}

.stack-card[data-state="past"] .stack-card-inner {
  /* 高斯模糊随盖住比例增强 */
  filter: blur(calc(var(--stack-p, 0) * 12px))
    brightness(calc(1 - var(--stack-p, 0) * 0.22))
    saturate(calc(1 - var(--stack-p, 0) * 0.35));
  transform: scale(calc(1 - var(--stack-p, 0) * 0.045));
  opacity: calc(1 - var(--stack-p, 0) * 0.28);
}

/* 兼容旧标记 */
.stack-card[data-overlapped="1"] .stack-card-inner {
  filter: blur(calc(var(--stack-p) * 12px))
    brightness(calc(1 - var(--stack-p) * 0.22));
  transform: scale(calc(1 - var(--stack-p) * 0.045));
  opacity: calc(1 - var(--stack-p) * 0.28);
}

.card-media {
  position: relative;
  min-height: 240px;
  padding: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.card-media.m1 {
  background:
    radial-gradient(ellipse 80% 70% at 30% 30%, rgba(184, 85, 47, 0.14), transparent 60%),
    linear-gradient(150deg, #FDF8EF, #F5EBD8);
}

.card-media.m2 {
  background:
    radial-gradient(ellipse 70% 60% at 70% 40%, rgba(95, 127, 82, 0.12), transparent 55%),
    linear-gradient(150deg, #FDF8EF, #F0E8D8);
}

.card-media.m3 {
  background:
    radial-gradient(ellipse 60% 70% at 40% 60%, rgba(176, 122, 42, 0.12), transparent 60%),
    linear-gradient(160deg, #FAF5EC, #F3EAD9);
}

.card-media.m4 {
  background:
    radial-gradient(ellipse 80% 50% at 50% 20%, rgba(184, 85, 47, 0.10), transparent 55%),
    linear-gradient(150deg, #FDF8EF, #F5EBD8);
}

.mock-ui {
  width: min(100%, 320px);
  border-radius: 12px;
  border: 1px solid var(--line-2);
  background: var(--paper);
  padding: 14px;
  box-shadow: var(--shadow-1);
}

.mock-bar {
  display: flex;
  gap: 5px;
  margin-bottom: 14px;
}

.mock-bar i {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--line-2);
}

.mock-bar i:first-child { background: var(--accent); }

.mock-row {
  height: 9px;
  border-radius: 5px;
  background: linear-gradient(90deg, var(--line-2), var(--line));
  margin-bottom: 9px;
}

.mock-row.short { width: 58%; }

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 10px;
}

.tag-row span {
  font-family: var(--font-code);
  font-size: 10px;
  color: var(--accent-deep);
  background: var(--accent-soft);
  border: 1px solid rgba(184, 85, 47, 0.15);
  padding: 3px 8px;
  border-radius: 999px;
}

.swatch-row {
  display: flex;
  gap: 8px;
  margin: 8px 0 14px;
}

.swatch-row i {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  border: 1px solid var(--line);
}

.mini-code {
  font-family: var(--font-code);
  font-size: 11.5px;
  line-height: 1.7;
  color: var(--ink-2);
  background: var(--paper-2);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px;
  margin: 6px 0 12px;
}

.mini-code .k { color: var(--accent-deep); }
.mini-code .v { color: var(--green); }
.mini-code .n { color: var(--amber); }

.lab-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  height: 110px;
  margin: 8px 0;
}

.lab-pane {
  border-radius: 10px;
  background: repeating-linear-gradient(
    180deg,
    var(--line) 0 8px,
    transparent 8px 18px
  );
  border: 1px solid var(--line-2);
}

.lab-pane.preview {
  background:
    radial-gradient(circle at 40% 40%, var(--accent-soft), transparent 65%),
    var(--paper-2);
}

.card-body {
  padding: clamp(24px, 3.5vw, 40px);
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 12px;
  width: 100%;
  min-width: 0;
  background: linear-gradient(160deg, rgba(255, 253, 248, 0.5), transparent 55%);
}

.card-num {
  font-family: var(--font-code);
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--accent);
  flex: none;
}

.card-body h3 {
  font-size: clamp(22px, 2.6vw, 30px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
  color: var(--ink);
  max-width: 100%;
  overflow-wrap: anywhere;
}

.card-body p {
  color: var(--ink-2);
  font-size: 14.5px;
  line-height: 1.85;
  max-width: 52ch;
  width: 100%;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-top: 4px;
}

.card-tags li {
  font-family: var(--font-code);
  font-size: 11px;
  color: var(--accent-deep);
  padding: 4px 11px;
  border-radius: 999px;
  border: 1px solid rgba(184, 85, 47, 0.18);
  background: var(--accent-softer);
}

.card-link {
  display: inline-flex;
  align-items: center;
  margin-top: 8px;
  font-size: 13.5px;
  font-weight: 700;
  color: var(--accent-deep);
  transition: transform 0.35s var(--ease-out), color 0.25s;
  width: fit-content;
}

.card-link:hover {
  transform: translateX(4px);
  color: var(--accent);
}

/* 路线阶段卡 */
.path-sec .stack-card {
  min-height: min(48vh, 380px);
}

.path-card .stack-card-inner {
  grid-template-columns: 1fr;
}

.path-card[data-state="todo"] .card-num {
  color: var(--ink-3);
}

.path-card[data-state="todo"] {
  background: var(--paper-2);
}

.path-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 6px;
}

.path-links a {
  font-size: 12.5px;
  font-weight: 700;
  color: #FFF7EF;
  background: linear-gradient(135deg, var(--accent), var(--accent-deep));
  padding: 6px 14px;
  border-radius: 999px;
  transition: transform 0.25s var(--ease-out), box-shadow 0.25s;
  box-shadow: 0 3px 10px rgba(154, 68, 35, 0.18);
}

.path-links a:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 18px rgba(154, 68, 35, 0.28);
}

.path-card[data-state="todo"] .path-links a {
  color: var(--ink-2);
  background: var(--paper);
  border: 1px solid var(--line-2);
  box-shadow: none;
}

.path-card[data-state="todo"] .path-links a:hover {
  color: var(--accent-deep);
  border-color: var(--accent);
}

.card-tags li.hot {
  color: var(--green);
  background: var(--green-soft);
  border-color: rgba(95, 127, 82, 0.2);
}

@media (max-width: 860px) {
  .stack-card {
    position: relative;
    top: auto !important;
    min-height: 0;
  }
  .stack-card-inner {
    grid-template-columns: 1fr;
    min-height: 0;
  }
  .stack-card[data-overlapped="1"] .stack-card-inner {
    transform: none;
    opacity: 1;
  }
  .card-media { min-height: 200px; }
}

/* =========================================================
   章节
   ========================================================= */
.chapters-sec {
  padding: 72px clamp(20px, 5vw, 56px) 96px;
  max-width: calc(var(--max) + 80px);
  margin: 0 auto;
  background:
    linear-gradient(180deg, transparent, rgba(253, 248, 239, 0.7) 12%, rgba(253, 248, 239, 0.7) 88%, transparent);
}

.chapters-head {
  margin-bottom: 36px;
  max-width: 560px;
}

.chapter-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.chapter-row {
  display: grid;
  grid-template-columns: 1fr minmax(72px, 140px) 64px;
  align-items: center;
  gap: 16px;
  padding: 16px 18px;
  border-radius: var(--r-card);
  border: 1px solid transparent;
  transition: background 0.35s var(--ease-out), border-color 0.35s, transform 0.4s var(--ease-out);
}

.chapter-row:hover {
  background: var(--paper);
  border-color: var(--line);
  transform: translateX(4px);
  box-shadow: var(--shadow-1);
}

.ch-main {
  display: flex;
  align-items: center;
  gap: 16px;
  min-width: 0;
}

.ch-no {
  font-family: var(--font-code);
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.08em;
  flex: none;
}

.ch-main h3 {
  font-size: 16.5px;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 2px;
  color: var(--ink);
}

.ch-main p {
  font-size: 12.5px;
  color: var(--ink-3);
  line-height: 1.55;
}

.ch-bar {
  height: 3px;
  border-radius: 3px;
  background: var(--line);
  overflow: hidden;
}

.ch-bar i {
  display: block;
  height: 100%;
  width: var(--w);
  border-radius: 3px;
  background: linear-gradient(90deg, var(--accent), var(--amber));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 1s var(--ease-out);
}

.chapter-row.is-in .ch-bar i,
html.reduced .ch-bar i {
  transform: scaleX(1);
}

.ch-count {
  font-family: var(--font-code);
  font-size: 11.5px;
  color: var(--ink-3);
  text-align: right;
  letter-spacing: 0.04em;
}

@media (max-width: 640px) {
  .chapter-row {
    grid-template-columns: 1fr;
    gap: 8px;
  }
  .ch-bar, .ch-count { grid-column: 1; }
  .ch-count { text-align: left; }
}

/* =========================================================
   学习方法
   ========================================================= */
.method-sec {
  padding: 72px clamp(20px, 5vw, 56px) 88px;
  max-width: calc(var(--max) + 80px);
  margin: 0 auto;
}

.method-head {
  margin-bottom: 32px;
  max-width: 560px;
}

.method-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 14px;
}

.method-card {
  padding: 24px 22px;
  border-radius: var(--r-card);
  border: 1px solid var(--line);
  background: var(--paper);
  box-shadow: var(--shadow-1);
  transition: transform 0.45s var(--ease-out), box-shadow 0.45s var(--ease-out),
    border-color 0.3s;
}

.method-card:hover {
  transform: translateY(-4px);
  border-color: rgba(184, 85, 47, 0.28);
  box-shadow: var(--shadow-2);
}

.m-no {
  font-family: var(--font-code);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--accent);
  display: block;
  margin-bottom: 14px;
}

.method-card h3 {
  font-size: 17px;
  font-weight: 800;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.method-card p {
  font-size: 13.5px;
  color: var(--ink-2);
  line-height: 1.75;
}

/* =========================================================
   实验台
   ========================================================= */
.lab-sec {
  padding: 56px clamp(20px, 5vw, 56px) 96px;
  max-width: calc(var(--max) + 80px);
  margin: 0 auto;
}

.lab-grid {
  display: grid;
  grid-template-columns: 1fr 1.15fr;
  gap: clamp(28px, 4vw, 56px);
  align-items: center;
}

.lab-copy .btn {
  margin-top: 22px;
}

.lab-points {
  margin-top: 22px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.lab-points li {
  font-size: 14.5px;
  color: var(--ink-2);
  padding-left: 16px;
  border-left: 2px solid rgba(184, 85, 47, 0.4);
  line-height: 1.7;
}

.lab-points b {
  color: var(--ink);
  margin-right: 6px;
}

.lab-window {
  border-radius: 16px;
  border: 1px solid var(--line-2);
  background: var(--paper);
  overflow: hidden;
  box-shadow: var(--shadow-pop);
}

.lab-titlebar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  background: var(--paper-2);
}

.lab-titlebar .dots {
  display: flex;
  gap: 5px;
}

.lab-titlebar .dots i {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--line-2);
}

.lab-titlebar .dots i:first-child { background: var(--accent); }

.lab-name {
  font-family: var(--font-code);
  font-size: 11.5px;
  color: var(--ink-3);
  flex: 1;
}

.lab-badge {
  font-family: var(--font-code);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--green);
  padding: 3px 8px;
  border-radius: 6px;
  background: var(--green-soft);
  border: 1px solid rgba(95, 127, 82, 0.22);
}

.lab-body {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  min-height: 250px;
}

.lab-code {
  padding: 18px 16px;
  font-family: var(--font-code);
  font-size: 12px;
  line-height: 1.75;
  color: var(--ink-2);
  border-right: 1px solid var(--line);
  overflow: auto;
  background: var(--paper-2);
}

.lab-code .k { color: var(--accent-deep); }
.lab-code .p { color: var(--ink-3); }
.lab-code .v { color: var(--green); }
.lab-code .n { color: var(--amber); }

.lab-preview {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 9px;
  padding: 24px 18px;
  background:
    radial-gradient(ellipse 80% 60% at 50% 30%, rgba(184, 85, 47, 0.08), transparent 70%),
    var(--bg);
}

.preview-card {
  height: 38px;
  border-radius: 9px;
  border: 1px solid var(--line);
  background: var(--paper);
  box-shadow: var(--shadow-1);
  animation: previewIn 2.8s var(--ease-out) infinite;
  opacity: 0;
  transform: translateY(14px);
}

.preview-card.p1 { animation-delay: 0s; width: 100%; }
.preview-card.p2 { animation-delay: 0.18s; width: 86%; }
.preview-card.p3 { animation-delay: 0.36s; width: 72%; }

@keyframes previewIn {
  0% { opacity: 0; transform: translateY(14px); }
  18%, 72% { opacity: 1; transform: none; }
  92%, 100% { opacity: 0; transform: translateY(-8px); }
}

@media (max-width: 960px) {
  .lab-grid { grid-template-columns: 1fr; }
  .lab-body { grid-template-columns: 1fr; }
  .lab-code { border-right: none; border-bottom: 1px solid var(--line); }
}

/* =========================================================
   CTA
   ========================================================= */
.cta-sec {
  position: relative;
  padding: 100px clamp(20px, 5vw, 56px) 80px;
  text-align: center;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  background:
    radial-gradient(ellipse 60% 50% at 50% 30%, rgba(184, 85, 47, 0.10), transparent 65%),
    var(--bg);
}

.cta-orb {
  position: absolute;
  width: min(60vw, 560px);
  height: min(60vw, 560px);
  top: 40%;
  left: 50%;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  background: radial-gradient(circle, rgba(184, 85, 47, 0.12), transparent 65%);
  filter: blur(30px);
  pointer-events: none;
}

.cta-sec .sec-kicker {
  justify-content: center;
}

.cta-sec .sec-kicker::before { display: none; }

.cta-title {
  position: relative;
  font-size: clamp(32px, 5.5vw, 60px);
  font-weight: 800;
  letter-spacing: -0.035em;
  line-height: 1.15;
  margin-bottom: 18px;
  max-width: 12em;
  color: var(--ink);
}

.cta-title .line { display: block; }

.cta-title .accent .char {
  background: linear-gradient(135deg, var(--accent), var(--accent-deep));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.cta-sec .sec-desc {
  margin: 0 auto 28px;
  text-align: center;
}

.cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  position: relative;
}

/* =========================================================
   FOOTER
   ========================================================= */
.site-foot {
  border-top: 1px solid var(--line);
  padding: 36px clamp(20px, 5vw, 56px) 44px;
  background: var(--paper-2);
}

.foot-inner {
  max-width: var(--max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 20px;
  align-items: center;
}

.foot-brand {
  display: flex;
  align-items: center;
  gap: 11px;
}

.foot-brand b {
  display: block;
  font-size: 13.5px;
}

.foot-brand small {
  font-size: 11.5px;
  color: var(--ink-3);
}

.foot-links {
  display: flex;
  gap: 20px;
  font-size: 12.5px;
  color: var(--ink-2);
  font-weight: 600;
}

.foot-links a:hover { color: var(--accent-deep); }

.foot-copy {
  grid-column: 1 / -1;
  font-family: var(--font-code);
  font-size: 10.5px;
  color: var(--ink-3);
  letter-spacing: 0.05em;
  padding-top: 10px;
  border-top: 1px solid var(--line);
}

@media (max-width: 640px) {
  .foot-inner { grid-template-columns: 1fr; }
}

/* =========================================================
   Reduced motion
   ========================================================= */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .reveal, .word .char {
    opacity: 1 !important;
    transform: none !important;
  }
}


/* 跳转遮罩 + 目标标题 */
.sx-mask {
  position: fixed; inset: 0; z-index: 10050;
  display: flex; align-items: center; justify-content: center;
  pointer-events: none; opacity: 0;
  background: linear-gradient(165deg, #1a1510, #2a221a 45%, #1a1510);
  transform: scaleY(0.08); transform-origin: bottom;
  transition: transform .55s cubic-bezier(.16,1,.3,1), opacity .4s;
}
.sx-mask.in { opacity: 1; transform: scaleY(1); pointer-events: auto; }
.sx-mask.out { opacity: 0; transform: scaleY(.06); transform-origin: top; }
.sx-mask-inner { display: flex; flex-direction: column; align-items: center; gap: 12px; }
.sx-mask-label { font-family: var(--font-code); font-size: 10px; letter-spacing: .28em; color: rgba(247,241,232,.4); }
.sx-mask-title {
  font-size: 22px; font-weight: 800; color: #F7F1E8; text-align: center;
  opacity: 0; transform: translateY(12px);
  transition: opacity .45s, transform .55s cubic-bezier(.34,1.25,.44,1);
}
.sx-mask-title.show { opacity: 1; transform: none; }
.sx-mask-bar { width: min(220px, 55vw); height: 2px; background: rgba(247,241,232,.12); border-radius: 2px; overflow: hidden; }
.sx-mask-bar i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, #C86035, #E8A87C); border-radius: 2px; }
.sx-mask.in .sx-mask-bar i { animation: sx-mask-load .5s cubic-bezier(.16,1,.3,1) forwards; }
@keyframes sx-mask-load { to { width: 100%; } }