/* ============================================
   朱身勇个人网站 · 样式表
   移动优先 · CSS Grid/Flexbox · 自定义属性
   ============================================ */

/* ---------- 设计令牌 ---------- */
:root {
  /* 色彩 */
  --navy-900: #10233f;
  --navy-800: #16304f;
  --navy-700: #1a365d;
  --navy-600: #24497a;
  --gold-500: #d4af37;
  --gold-400: #e2c25c;
  --gold-100: #faf3dd;
  --ink-900: #1c2430;
  --ink-700: #3d4a5c;
  --ink-500: #64748b;
  --ink-300: #9aa7b8;
  --bg-paper: #fafaf7;
  --bg-white: #ffffff;
  --bg-soft: #f4f1ea;

  /* 字体 */
  --font-serif: "Songti SC", "STSong", "Noto Serif SC", "SimSun", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;

  /* 间距与圆角 */
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --section-gap: clamp(4rem, 8vw, 7rem);

  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(16, 35, 63, 0.06);
  --shadow-md: 0 8px 30px rgba(16, 35, 63, 0.1);
  --shadow-lg: 0 20px 60px rgba(16, 35, 63, 0.16);

  /* 动效 */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ---------- 基础重置 ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 5rem; /* 锚点定位时避开固定导航 */
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--ink-700);
  background: var(--bg-paper);
  -webkit-font-smoothing: antialiased;
}

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

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

ul {
  list-style: none;
}

button {
  font: inherit;
  border: none;
  background: none;
  cursor: pointer;
}

/* 键盘焦点可见性（无障碍） */
:focus-visible {
  outline: 3px solid var(--gold-500);
  outline-offset: 3px;
  border-radius: 4px;
}

.container {
  width: min(100% - 2.5rem, 1140px);
  margin-inline: auto;
}

.hide-mobile {
  display: none;
}

/* ---------- 导航栏 ---------- */
.navbar {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 1000;
  background: rgba(250, 250, 247, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(16, 35, 63, 0.06);
  transition: box-shadow 0.3s var(--ease);
}

.navbar.scrolled {
  box-shadow: var(--shadow-md);
}

.nav-container {
  width: min(100% - 2.5rem, 1140px);
  margin-inline: auto;
  height: 4.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  flex-shrink: 0;
}

.logo-mark {
  width: 2.5rem;
  height: 2.5rem;
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, var(--navy-700), var(--navy-900));
  color: var(--gold-400);
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  border-radius: 10px;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--navy-800);
}

.logo-text small {
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 0.7rem;
  letter-spacing: 0.35em;
  color: var(--ink-500);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-link {
  position: relative;
  padding: 0.5rem 0.9rem;
  font-size: 0.95rem;
  color: var(--ink-700);
  border-radius: 8px;
  transition: color 0.25s var(--ease);
}

.nav-link:hover {
  color: var(--navy-700);
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0.2rem;
  width: 0;
  height: 2px;
  background: var(--gold-500);
  transform: translateX(-50%);
  transition: width 0.3s var(--ease);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: calc(100% - 1.8rem);
}

.nav-link.active {
  color: var(--navy-700);
  font-weight: 600;
}

.nav-cta {
  margin-left: 0.5rem;
  padding: 0.55rem 1.25rem;
  background: var(--navy-700);
  color: #fff;
  border-radius: 999px;
  transition: background 0.25s var(--ease), transform 0.25s var(--ease);
}

.nav-cta::after {
  display: none;
}

.nav-cta:hover {
  background: var(--navy-900);
  transform: translateY(-1px);
}

/* 汉堡按钮（移动端） */
.nav-toggle {
  display: none;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: 10px;
  position: relative;
  z-index: 1001;
}

.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 1.4rem;
  height: 2px;
  background: var(--navy-800);
  border-radius: 2px;
  transition: transform 0.3s var(--ease), opacity 0.2s;
}

.hamburger::before,
.hamburger::after {
  content: "";
  position: absolute;
  left: 0.675rem;
}

.hamburger::before {
  top: 0.95rem;
}

.hamburger::after {
  bottom: 0.95rem;
}

.nav-toggle[aria-expanded="true"] .hamburger {
  transform: rotate(45deg);
  position: absolute;
  top: 1.28rem;
  left: 0.675rem;
}

.nav-toggle[aria-expanded="true"] .hamburger::before {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .hamburger::after {
  transform: rotate(90deg);
  bottom: auto;
  top: 0;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100dvh; /* 移动端视口高度，避免地址栏问题 */
  display: flex;
  align-items: center;
  padding: 7rem 0 4rem;
  overflow: hidden;
  background:
    radial-gradient(ellipse 80% 60% at 85% 10%, rgba(212, 175, 55, 0.14), transparent 60%),
    radial-gradient(ellipse 70% 70% at 10% 90%, rgba(26, 54, 93, 0.1), transparent 60%),
    linear-gradient(175deg, #f2ede1 0%, var(--bg-paper) 45%, #fff 100%);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(45deg, rgba(26, 54, 93, 0.025) 0 1px, transparent 1px 28px),
    repeating-linear-gradient(-45deg, rgba(26, 54, 93, 0.02) 0 1px, transparent 1px 28px);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  display: grid;
  gap: 3rem;
  align-items: center;
}

.hero-badge {
  display: inline-block;
  align-self: flex-start;
  padding: 0.35rem 1rem;
  font-size: 0.8rem;
  letter-spacing: 0.2em;
  color: var(--navy-700);
  background: rgba(26, 54, 93, 0.07);
  border: 1px solid rgba(26, 54, 93, 0.14);
  border-radius: 999px;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(3.5rem, 10vw, 6.5rem);
  font-weight: 700;
  line-height: 1.1;
  color: var(--navy-900);
  letter-spacing: 0.08em;
  margin: 1.2rem 0 0.6rem;
  background: linear-gradient(120deg, var(--navy-900) 30%, var(--navy-600) 70%, var(--gold-500) 105%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-family: var(--font-serif);
  font-size: clamp(1.15rem, 2.6vw, 1.6rem);
  color: var(--navy-700);
  letter-spacing: 0.12em;
  border-left: 3px solid var(--gold-500);
  padding-left: 1rem;
  margin-bottom: 1.5rem;
}

.hero-desc {
  font-size: 1.02rem;
  color: var(--ink-500);
  margin-bottom: 2.2rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.8rem 2rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: 999px;
  transition: transform 0.25s var(--ease), box-shadow 0.25s var(--ease),
    background 0.25s var(--ease), color 0.25s var(--ease);
}

.btn-primary {
  background: linear-gradient(135deg, var(--navy-700), var(--navy-900));
  color: #fff;
  box-shadow: 0 8px 24px rgba(26, 54, 93, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(26, 54, 93, 0.4);
}

.btn-ghost {
  border: 1.5px solid var(--navy-700);
  color: var(--navy-700);
}

.btn-ghost:hover {
  background: var(--navy-700);
  color: #fff;
  transform: translateY(-2px);
}

.btn-outline {
  border: 1.5px solid rgba(255, 255, 255, 0.6);
  color: #fff;
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.12);
  transform: translateY(-2px);
}

.btn-lg {
  padding: 1rem 2.5rem;
  font-size: 1.05rem;
}

/* Hero 视觉卡片 */
.hero-visual {
  display: none;
}

.scroll-hint {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  width: 1.5rem;
  height: 2.5rem;
  border: 2px solid var(--navy-600);
  border-radius: 999px;
  display: flex;
  justify-content: center;
  padding-top: 0.5rem;
}

.scroll-hint span {
  width: 4px;
  height: 8px;
  background: var(--navy-600);
  border-radius: 4px;
  animation: scrollDot 1.8s infinite var(--ease);
}

@keyframes scrollDot {
  0% {
    transform: translateY(0);
    opacity: 1;
  }
  70% {
    transform: translateY(0.75rem);
    opacity: 0;
  }
  100% {
    transform: translateY(0);
    opacity: 0;
  }
}

/* ---------- 数据条 ---------- */
.stats {
  background: var(--navy-900);
  color: #fff;
  padding: 3rem 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2.5rem 1rem;
  text-align: center;
}

.stat-item strong {
  font-family: var(--font-serif);
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  font-weight: 700;
  color: var(--gold-400);
}

.stat-item em {
  font-style: normal;
  font-size: 1rem;
  color: var(--gold-400);
  margin-left: 0.15rem;
}

.stat-item span {
  display: block;
  font-size: 0.85rem;
  letter-spacing: 0.12em;
  color: rgba(255, 255, 255, 0.65);
  margin-top: 0.4rem;
}

/* ---------- 通用 Section ---------- */
.section {
  padding-block: var(--section-gap);
}

.section-head {
  text-align: center;
  margin-bottom: clamp(2.5rem, 6vw, 4rem);
}

.section-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.45em;
  text-transform: uppercase;
  color: var(--gold-500);
  margin-bottom: 0.6rem;
}

.section-head h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 4.5vw, 2.6rem);
  font-weight: 700;
  color: var(--navy-900);
  letter-spacing: 0.06em;
}

.section-desc {
  margin-top: 0.8rem;
  color: var(--ink-500);
  font-size: 1rem;
}

/* ---------- 关于 ---------- */
.about {
  background: var(--bg-white);
}

.about-grid {
  display: grid;
  gap: 3rem;
}

.about-text .lead {
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--ink-900);
  margin-bottom: 1.2rem;
}

.about-text p {
  margin-bottom: 1.1rem;
}

.about-credentials {
  background: linear-gradient(160deg, var(--navy-800), var(--navy-900));
  border-radius: var(--radius-lg);
  padding: 2.2rem 2rem;
  color: #fff;
  align-self: start;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.about-credentials::before {
  content: "";
  position: absolute;
  inset: auto -30% -40% auto;
  width: 60%;
  aspect-ratio: 1;
  background: radial-gradient(circle, rgba(212, 175, 55, 0.25), transparent 70%);
  pointer-events: none;
}

.about-credentials h3 {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  letter-spacing: 0.1em;
  margin-bottom: 1.4rem;
  padding-bottom: 0.9rem;
  border-bottom: 1px solid rgba(212, 175, 55, 0.35);
}

.credential-list li {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  padding: 0.55rem 0;
  font-size: 0.95rem;
  color: rgba(255, 255, 255, 0.88);
  border-bottom: 1px dashed rgba(255, 255, 255, 0.08);
}

.credential-list li:last-child {
  border-bottom: none;
}

.credential-list i {
  font-style: normal;
  color: var(--gold-400);
  font-size: 0.7rem;
  line-height: 2;
  flex-shrink: 0;
}

/* ---------- 核心体系 ---------- */
.system {
  background:
    radial-gradient(ellipse 60% 40% at 90% 5%, rgba(212, 175, 55, 0.07), transparent 60%),
    var(--bg-soft);
}

.system-grid {
  display: grid;
  gap: 1.8rem;
}

.system-card {
  background: var(--bg-white);
  border-radius: var(--radius-lg);
  padding: 2.4rem 2rem 2.2rem;
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(26, 54, 93, 0.06);
  position: relative;
  overflow: hidden;
  transition: transform 0.35s var(--ease), box-shadow 0.35s var(--ease);
}

.system-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--navy-700), var(--gold-500));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s var(--ease);
}

.system-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.system-card:hover::before {
  transform: scaleX(1);
}

.card-icon {
  font-family: var(--font-serif);
  font-size: 2.6rem;
  font-weight: 700;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1.5px var(--gold-500);
  margin-bottom: 1.2rem;
}

.system-card h3 {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  color: var(--navy-900);
  letter-spacing: 0.05em;
  margin-bottom: 0.9rem;
}

.system-card p {
  font-size: 0.95rem;
  margin-bottom: 1.2rem;
}

.card-points {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.card-points li {
  font-size: 0.8rem;
  padding: 0.3rem 0.85rem;
  background: var(--gold-100);
  color: var(--navy-700);
  border-radius: 999px;
  font-weight: 500;
}

/* ---------- 著作 ---------- */
.books {
  background: var(--bg-white);
}

.books-grid {
  display: grid;
  gap: 2.5rem;
}

.book-card {
  display: grid;
  gap: 1.5rem;
}

.book-cover {
  aspect-ratio: 3 / 4;
  max-width: 300px;
  margin-inline: auto;
  width: 100%;
  border-radius: 6px 14px 14px 6px;
  position: relative;
  box-shadow: var(--shadow-lg);
  transition: transform 0.4s var(--ease);
  display: flex;
  align-items: center;
  justify-content: center;
  /* 书脊 */
  border-left: 10px solid rgba(0, 0, 0, 0.28);
}

.book-card[data-visible="true"]:hover .book-cover {
  transform: perspective(900px) rotateY(-7deg) translateY(-4px);
}

.cover-inner {
  text-align: center;
  padding: 2rem 1.2rem;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
  width: 100%;
  height: 100%;
  align-items: center;
  justify-content: center;
  background: linear-gradient(160deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0));
}

.cover-author {
  font-size: 0.8rem;
  letter-spacing: 0.4em;
  color: rgba(255, 255, 255, 0.85);
}

.cover-title {
  font-family: var(--font-serif);
  font-size: clamp(1.3rem, 3vw, 1.6rem);
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.1em;
  writing-mode: horizontal-tb;
}

.cover-sub {
  font-size: 0.78rem;
  color: rgba(255, 255, 255, 0.75);
  letter-spacing: 0.15em;
  padding-top: 0.8rem;
  border-top: 1px solid rgba(255, 255, 255, 0.3);
}

.book-info {
  text-align: center;
}

.book-info h3 {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  color: var(--navy-900);
  margin-bottom: 0.3rem;
}

.book-label {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--navy-700);
  background: rgba(26, 54, 93, 0.07);
  padding: 0.25rem 0.9rem;
  border-radius: 999px;
  margin-bottom: 0.9rem;
}

.book-desc {
  font-size: 0.92rem;
  color: var(--ink-500);
}

/* ---------- 课程 ---------- */
.courses {
  background:
    linear-gradient(180deg, var(--navy-900), var(--navy-800));
  color: rgba(255, 255, 255, 0.85);
}

.courses .section-head h2,
.courses .section-head .section-desc {
  color: #fff;
}

.courses .section-desc {
  color: rgba(255, 255, 255, 0.6);
}

.courses-grid {
  display: grid;
  gap: 1.4rem;
}

.course-item {
  display: flex;
  gap: 1.5rem;
  padding: 1.8rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-md);
  backdrop-filter: blur(4px);
  transition: background 0.3s var(--ease), transform 0.3s var(--ease);
}

.course-item:hover {
  background: rgba(255, 255, 255, 0.09);
  transform: translateX(6px);
}

.course-number {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 700;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1.2px var(--gold-400);
  flex-shrink: 0;
  padding-top: 0.2rem;
}

.course-item h3 {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: #fff;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.course-item p {
  font-size: 0.92rem;
}

.service-note {
  margin-top: 2.5rem;
  padding: 1.8rem 2rem;
  background: rgba(212, 175, 55, 0.1);
  border: 1px solid rgba(212, 175, 55, 0.3);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
}

.service-note strong {
  color: var(--gold-400);
}

/* ---------- 媒体影响 ---------- */
.media {
  background: var(--bg-white);
}

.media-grid {
  display: grid;
  gap: 1.6rem;
}

.media-item {
  padding: 2rem 1.8rem;
  background: var(--bg-paper);
  border-radius: var(--radius-md);
  border-left: 3px solid var(--gold-500);
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
}

.media-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.media-item h3 {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--navy-900);
  margin-bottom: 0.7rem;
  letter-spacing: 0.06em;
}

.media-item p {
  font-size: 0.92rem;
  color: var(--ink-500);
}

/* ---------- 联系 ---------- */
.contact {
  padding-bottom: var(--section-gap);
  background: var(--bg-paper);
}

.contact-card {
  text-align: center;
  padding: clamp(3rem, 8vw, 5rem) 2rem;
  border-radius: var(--radius-lg);
  background:
    radial-gradient(ellipse 70% 90% at 50% 120%, rgba(212, 175, 55, 0.22), transparent 60%),
    linear-gradient(150deg, var(--navy-700), var(--navy-900));
  color: #fff;
  box-shadow: var(--shadow-lg);
}

.contact-card h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.7rem, 4vw, 2.4rem);
  letter-spacing: 0.08em;
  margin-bottom: 1.2rem;
}

.contact-card > p {
  color: rgba(255, 255, 255, 0.78);
  margin-bottom: 2.2rem;
}

.contact-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 2.2rem;
}

.contact-actions .btn-primary {
  background: linear-gradient(135deg, var(--gold-400), var(--gold-500));
  color: var(--navy-900);
  box-shadow: 0 8px 24px rgba(212, 175, 55, 0.35);
}

.contact-actions .btn-primary:hover {
  box-shadow: 0 12px 32px rgba(212, 175, 55, 0.5);
}

.contact-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.6rem;
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.55);
}

.contact-meta .divider {
  color: rgba(255, 255, 255, 0.25);
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--navy-900);
  color: rgba(255, 255, 255, 0.6);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  gap: 1.8rem;
  padding: 3rem 0 2rem;
  align-items: center;
  text-align: center;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

.footer-brand .logo-mark {
  width: 2.75rem;
  height: 2.75rem;
}

.footer-brand strong {
  display: block;
  font-family: var(--font-serif);
  font-size: 1.2rem;
  color: #fff;
  letter-spacing: 0.15em;
}

.footer-brand small {
  font-size: 0.75rem;
  letter-spacing: 0.2em;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem 1.8rem;
  font-size: 0.9rem;
}

.footer-nav a {
  transition: color 0.25s;
}

.footer-nav a:hover {
  color: var(--gold-400);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding: 1.4rem 0;
  font-size: 0.8rem;
  text-align: center;
  color: rgba(255, 255, 255, 0.4);
}

/* ---------- 返回顶部 ---------- */
.back-to-top {
  position: fixed;
  right: 1.4rem;
  bottom: 1.4rem;
  z-index: 900;
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background: var(--navy-700);
  color: #fff;
  font-size: 1.2rem;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 0.3s var(--ease), transform 0.3s var(--ease),
    visibility 0.3s, background 0.25s;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--navy-900);
}

/* ---------- 滚动动画 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}

.reveal[data-visible="true"] {
  opacity: 1;
  transform: none;
}

/* 用户偏好减少动画 */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

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

  .scroll-hint span {
    animation: none;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}

/* ============================================
   响应式断点
   ============================================ */

/* ≥ 640px：小平板 / 大屏手机横屏 */
@media (min-width: 640px) {
  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .books-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .media-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .courses-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .course-item {
    flex-direction: column;
    gap: 0.8rem;
  }

  .hide-mobile {
    display: inline;
  }

  .footer-inner {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

/* ≥ 900px：桌面端 */
@media (min-width: 900px) {
  .hero-inner {
    grid-template-columns: 1.15fr 0.85fr;
    gap: 4rem;
  }

  .hero-visual {
    display: block;
  }

  .visual-card {
    position: relative;
    aspect-ratio: 1;
    max-width: 380px;
    margin-inline: auto;
    width: 100%;
    border-radius: 50%;
    background:
      radial-gradient(circle at 35% 30%, rgba(255, 255, 255, 0.5), transparent 50%),
      linear-gradient(150deg, var(--navy-700), var(--navy-900));
    box-shadow: var(--shadow-lg), inset 0 0 60px rgba(212, 175, 55, 0.12);
    display: grid;
    place-items: center;
    animation: floatCard 7s ease-in-out infinite;
  }

  @keyframes floatCard {
    0%, 100% {
      transform: translateY(0);
    }
    50% {
      transform: translateY(-14px);
    }
  }

  .visual-ring {
    position: absolute;
    border-radius: 50%;
    border: 1px solid rgba(212, 175, 55, 0.35);
  }

  .ring-1 {
    inset: -8%;
    animation: spinSlow 26s linear infinite;
    border-style: dashed;
  }

  .ring-2 {
    inset: -18%;
    border-color: rgba(212, 175, 55, 0.16);
    animation: spinSlow 40s linear infinite reverse;
  }

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

  .visual-quote {
    text-align: center;
    padding: 2rem;
  }

  .visual-quote .quote-mark {
    font-family: var(--font-serif);
    font-size: 3.5rem;
    line-height: 0.6;
    color: var(--gold-400);
    display: block;
    margin-bottom: 1rem;
  }

  .visual-quote p {
    font-family: var(--font-serif);
    font-size: 1.35rem;
    color: #fff;
    letter-spacing: 0.15em;
    line-height: 2;
  }

  .system-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .about-grid {
    grid-template-columns: 1.4fr 1fr;
    gap: 4rem;
    align-items: start;
  }
}

/* 移动端抽屉导航（≤ 899px） */
@media (max-width: 899px) {
  .nav-toggle {
    display: block;
  }

  .nav-menu {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: min(78vw, 320px);
    flex-direction: column;
    align-items: flex-start;
    gap: 0.4rem;
    padding: 6rem 2rem 2rem;
    background: var(--bg-white);
    box-shadow: -12px 0 40px rgba(16, 35, 63, 0.15);
    transform: translateX(100%);
    transition: transform 0.4s var(--ease);
    z-index: 1000;
  }

  .nav-menu.open {
    transform: translateX(0);
  }

  .nav-link {
    width: 100%;
    padding: 0.85rem 1rem;
    font-size: 1.05rem;
    border-radius: 10px;
  }

  .nav-link::after {
    display: none;
  }

  .nav-link:active {
    background: var(--bg-soft);
  }

  .nav-cta {
    margin: 0.8rem 0 0;
    width: 100%;
    text-align: center;
  }

  /* 打开抽屉时锁住背景滚动 */
  body.menu-open {
    overflow: hidden;
  }
}

/* 超大屏 */
@media (min-width: 1400px) {
  .container,
  .nav-container {
    max-width: 1240px;
  }
}