/* ============================================
   麻豆tv在线表演艺术培训学院 - 主样式表
   版本: 1.0.0
   描述: 基于"深红+象牙白"色彩方案的学院官网样式
   ============================================ */

/* === CSS变量定义（全局主题色） === */
:root {
  --primary: #8B0000;       /* 深红色 - 主导航、核心按钮、重要标题 */
  --secondary: #DAA520;     /* 金色 - 星级评价、荣誉展示、次要按钮 */
  --bg: #FFFFF0;            /* 象牙白 - 全局背景 */
  --card-bg: #FFF8F0;       /* 浅暖色 - 卡片背景 */
  --accent: #B22222;        /* 火砖红 - 悬停效果、通知提示 */
  --text: #2C2C2C;          /* 深灰色 - 正文内容 */
  --text-light: #666666;    /* 浅灰色 - 辅助说明 */
  --border: #E0D8D0;        /* 边框颜色 */
  
  /* 字体变量 */
  --font-heading: 'Noto Serif SC', 'SimSun', serif;
  --font-body: 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
  --font-number: 'Roboto', 'Open Sans', sans-serif;
  
  /* 间距变量 */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-xxl: 5rem;
  
  /* 圆角 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  /* 阴影 */
  --shadow-sm: 0 2px 4px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.12);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.16);
  
  /* 过渡 */
  --transition: 0.3s ease;
  
  /* 容器宽度 */
  --container-max: 1200px;
}

/* === 全局重置（Reset） === */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  background-color: var(--bg);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--accent);
}

ul, ol {
  list-style: none;
}

button {
  cursor: pointer;
  border: none;
  outline: none;
  font-family: inherit;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

/* === 排版样式 === */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: var(--text);
  line-height: 1.4;
  margin-bottom: var(--spacing-sm);
}

h1 { font-size: 2.5rem; font-weight: 700; }
h2 { font-size: 2rem; font-weight: 700; }
h3 { font-size: 1.5rem; font-weight: 600; }
h4 { font-size: 1.25rem; font-weight: 600; }
h5 { font-size: 1.125rem; font-weight: 500; }
h6 { font-size: 1rem; font-weight: 500; }

p {
  margin-bottom: var(--spacing-sm);
  line-height: 1.8;
}

/* === 容器布局 === */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.section {
  padding: var(--spacing-xxl) 0;
}

.section__title {
  text-align: center;
  margin-bottom: var(--spacing-xl);
  color: var(--primary);
}

.section__title::after {
  content: '';
  display: block;
  width: 60px;
  height: 3px;
  background: var(--secondary);
  margin: var(--spacing-sm) auto 0;
}

.section__subtitle {
  text-align: center;
  color: var(--text-light);
  font-size: 1.1rem;
  margin-top: -1.5rem;
  margin-bottom: var(--spacing-xl);
}

/* === 顶部导航栏（Header） === */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(255, 255, 240, 0.98);
  transition: box-shadow var(--transition);
}

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

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-sm) var(--spacing-md);
  max-width: var(--container-max);
  margin: 0 auto;
}

.header__logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.header__logo img {
  height: 40px;
  width: auto;
}

.header__logo-text {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: var(--primary);
  font-weight: 700;
}

.nav__list {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
}

.nav__link {
  font-size: 0.95rem;
  color: var(--text);
  font-weight: 500;
  position: relative;
  padding: var(--spacing-xs) 0;
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: width var(--transition);
}

.nav__link:hover::after,
.nav__link--active::after {
  width: 100%;
}

.nav__link:hover {
  color: var(--primary);
}

.header__actions {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.header__search {
  position: relative;
}

.header__search-input {
  padding: 6px 32px 6px 12px;
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.875rem;
  width: 160px;
  transition: all var(--transition);
}

.header__search-input:focus {
  border-color: var(--primary);
  width: 200px;
  outline: none;
}

.header__search-btn {
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  color: var(--text-light);
}

/* 汉堡菜单按钮 */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  padding: 5px;
}

.hamburger__line {
  width: 24px;
  height: 2px;
  background: var(--text);
  transition: all var(--transition);
}

/* === 按钮样式 === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 500;
  transition: all var(--transition);
  text-align: center;
}

.btn--primary {
  background: var(--primary);
  color: #fff;
}

.btn--primary:hover {
  background: var(--accent);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn--secondary {
  background: var(--secondary);
  color: #fff;
}

.btn--secondary:hover {
  background: #C4941A;
  color: #fff;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn--outline {
  background: transparent;
  border: 2px solid var(--primary);
  color: var(--primary);
}

.btn--outline:hover {
  background: var(--primary);
  color: #fff;
  transform: translateY(-2px);
}

.btn--sm {
  padding: 8px 18px;
  font-size: 0.875rem;
}

.btn--lg {
  padding: 16px 36px;
  font-size: 1.125rem;
}

/* === 英雄区域（Hero Section） === */
.hero {
  position: relative;
  height: 100vh;
  min-height: 600px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  margin-top: 0;
}

.hero__bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: -2;
}

.hero__overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, rgba(139,0,0,0.7) 0%, rgba(0,0,0,0.5) 100%);
  z-index: -1;
}

.hero__content {
  text-align: center;
  color: #fff;
  padding: var(--spacing-lg);
  max-width: 800px;
}

.hero__title {
  font-size: 3rem;
  font-family: var(--font-heading);
  color: #fff;
  margin-bottom: var(--spacing-md);
  text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
  animation: fadeInUp 1s ease;
}

.hero__subtitle {
  font-size: 1.25rem;
  color: rgba(255,255,255,0.9);
  margin-bottom: var(--spacing-xl);
  animation: fadeInUp 1s ease 0.2s both;
}

.hero__actions {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeInUp 1s ease 0.4s both;
}

/* === 学院优势区 === */
.advantages {
  background: var(--card-bg);
}

.advantages__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-lg);
}

.advantage-card {
  text-align: center;
  padding: var(--spacing-xl) var(--spacing-md);
  background: #fff;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}

.advantage-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.advantage-card__icon {
  width: 64px;
  height: 64px;
  margin: 0 auto var(--spacing-md);
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 50%;
  color: #fff;
  font-size: 1.5rem;
}

.advantage-card__title {
  font-size: 1.125rem;
  margin-bottom: var(--spacing-xs);
  color: var(--primary);
}

.advantage-card__desc {
  color: var(--text-light);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* === 课程卡片网格 === */
.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.course-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  border: 1px solid var(--border);
}

.course-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.course-card__image {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16/9;
}

.course-card__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition);
}

.course-card:hover .course-card__image img {
  transform: scale(1.05);
}

.course-card__badge {
  position: absolute;
  top: 12px;
  left: 12px;
  padding: 4px 12px;
  background: var(--primary);
  color: #fff;
  font-size: 0.75rem;
  border-radius: 20px;
}

.course-card__body {
  padding: var(--spacing-md);
}

.course-card__title {
  font-size: 1.1rem;
  margin-bottom: var(--spacing-xs);
  font-family: var(--font-heading);
}

.course-card__meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  color: var(--text-light);
  font-size: 0.85rem;
  margin-bottom: var(--spacing-sm);
}

.course-card__rating {
  color: var(--secondary);
  font-family: var(--font-number);
}

.course-card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-sm) var(--spacing-md);
  border-top: 1px solid var(--border);
}

.course-card__price {
  font-family: var(--font-number);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
}

.course-card__price span {
  font-size: 0.8rem;
  color: var(--text-light);
  font-weight: 400;
}

/* === 师资卡片轮播 === */
.faculty-carousel {
  position: relative;
  overflow: hidden;
}

.faculty-carousel__track {
  display: flex;
  gap: var(--spacing-lg);
  transition: transform 0.5s ease;
}

.faculty-card {
  min-width: 280px;
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  border: 1px solid var(--border);
}

.faculty-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
}

.faculty-card__image {
  aspect-ratio: 3/4;
  overflow: hidden;
}

.faculty-card__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition);
}

.faculty-card:hover .faculty-card__image img {
  transform: scale(1.03);
}

.faculty-card__info {
  padding: var(--spacing-md);
  text-align: center;
}

.faculty-card__name {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: var(--primary);
  margin-bottom: 4px;
}

.faculty-card__title {
  color: var(--text-light);
  font-size: 0.9rem;
  margin-bottom: var(--spacing-xs);
}

.faculty-card__desc {
  font-size: 0.85rem;
  color: var(--text-light);
  line-height: 1.5;
}

.faculty-carousel__nav {
  display: flex;
  justify-content: center;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-lg);
}

.faculty-carousel__btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}

.faculty-carousel__btn:hover {
  background: var(--accent);
  transform: scale(1.1);
}

/* === 学习路径时间轴 === */
.timeline {
  position: relative;
  padding: var(--spacing-lg) 0;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--border);
  transform: translateX(-50%);
}

.timeline__item {
  display: flex;
  align-items: center;
  margin-bottom: var(--spacing-xl);
  position: relative;
}

.timeline__item:nth-child(odd) {
  flex-direction: row;
}

.timeline__item:nth-child(even) {
  flex-direction: row-reverse;
}

.timeline__content {
  width: 45%;
  padding: var(--spacing-md);
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border);
}

.timeline__dot {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 20px;
  background: var(--primary);
  border-radius: 50%;
  border: 4px solid var(--bg);
  box-shadow: var(--shadow-sm);
  z-index: 1;
}

.timeline__title {
  color: var(--primary);
  font-family: var(--font-heading);
  margin-bottom: var(--spacing-xs);
}

/* === 学员作品展示墙（瀑布流） === */
.masonry-gallery {
  columns: 3;
  column-gap: var(--spacing-md);
}

.masonry-gallery__item {
  break-inside: avoid;
  margin-bottom: var(--spacing-md);
  position: relative;
  border-radius: var(--radius-md);
  overflow: hidden;
}

.masonry-gallery__item img {
  width: 100%;
  display: block;
  transition: transform var(--transition);
}

.masonry-gallery__overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(139, 0, 0, 0.7);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition);
  color: #fff;
}

.masonry-gallery__item:hover .masonry-gallery__overlay {
  opacity: 1;
}

.masonry-gallery__item:hover img {
  transform: scale(1.05);
}

/* === 免费试听引导区（CTA横幅） === */
.cta-banner {
  background: linear-gradient(135deg, var(--primary) 0%, #5C0000 100%);
  color: #fff;
  padding: var(--spacing-xxl) 0;
  text-align: center;
}

.cta-banner__title {
  font-size: 1.8rem;
  color: #fff;
  margin-bottom: var(--spacing-md);
  font-family: var(--font-heading);
}

.cta-banner__desc {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.9);
  margin-bottom: var(--spacing-lg);
}

.cta-banner__form {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
  max-width: 500px;
  margin: 0 auto;
}

.cta-banner__input {
  flex: 1;
  padding: 14px 20px;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1rem;
}

.cta-banner__input:focus {
  outline: 2px solid var(--secondary);
}

/* === FAQ手风琴 === */
.faq__list {
  max-width: 800px;
  margin: 0 auto;
}

.faq__item {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-sm);
  overflow: hidden;
}

.faq__question {
  width: 100%;
  padding: var(--spacing-md);
  background: var(--card-bg);
  text-align: left;
  font-size: 1rem;
  font-weight: 500;
  color: var(--text);
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all var(--transition);
}

.faq__question:hover {
  background: #FFF0E0;
}

.faq__question--active {
  color: var(--primary);
  background: #FFF0E0;
}

.faq__icon {
  transition: transform var(--transition);
  font-size: 1.2rem;
}

.faq__question--active .faq__icon {
  transform: rotate(180deg);
}

.faq__answer {
  padding: 0 var(--spacing-md);
  max-height: 0;
  overflow: hidden;
  transition: all 0.4s ease;
  color: var(--text-light);
  line-height: 1.8;
}

.faq__answer--open {
  padding: var(--spacing-md);
  max-height: 500px;
}

/* === 试听视频弹窗 === */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 9999;
  display: none;
  align-items: center;
  justify-content: center;
}

.modal--active {
  display: flex;
}

.modal__overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.7);
  backdrop-filter: blur(4px);
}

.modal__content {
  position: relative;
  background: #000;
  border-radius: var(--radius-lg);
  overflow: hidden;
  max-width: 800px;
  width: 90%;
  animation: scaleIn 0.3s ease;
}

.modal__close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 36px;
  height: 36px;
  background: rgba(255,255,255,0.2);
  border-radius: 50%;
  color: #fff;
  font-size: 1.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1;
  transition: all var(--transition);
}

.modal__close:hover {
  background: rgba(255,255,255,0.4);
}

/* === 在线报名表单 === */
.enroll-form {
  max-width: 600px;
  margin: 0 auto;
  background: #fff;
  padding: var(--spacing-xl);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.enroll-form__progress {
  display: flex;
  justify-content: space-between;
  margin-bottom: var(--spacing-xl);
  position: relative;
}

.enroll-form__progress::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--border);
  transform: translateY(-50%);
  z-index: 0;
}

.enroll-form__step {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--border);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  font-weight: 600;
  position: relative;
  z-index: 1;
}

.enroll-form__step--active {
  background: var(--primary);
}

.enroll-form__step--completed {
  background: var(--secondary);
}

.form-group {
  margin-bottom: var(--spacing-md);
  position: relative;
}

.form-group__label {
  display: block;
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 6px;
  transition: all var(--transition);
}

.form-group__input {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 1rem;
  transition: all var(--transition);
}

.form-group__input:focus {
  border-color: var(--primary);
  outline: none;
  box-shadow: 0 0 0 3px rgba(139, 0, 0, 0.1);
}

.form-group__error {
  font-size: 0.8rem;
  color: var(--accent);
  margin-top: 4px;
  display: none;
}

/* === 课程进度环形图 === */
.progress-ring {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.progress-ring__svg {
  transform: rotate(-90deg);
}

.progress-ring__circle-bg {
  fill: none;
  stroke: var(--border);
  stroke-width: 8;
}

.progress-ring__circle {
  fill: none;
  stroke: var(--accent);
  stroke-width: 8;
  stroke-linecap: round;
  transition: stroke-dashoffset 1s ease;
}

.progress-ring__text {
  position: absolute;
  font-family: var(--font-number);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
}

/* === 底部区域（Footer） === */
.footer {
  background: #1a1a1a;
  color: #ccc;
  padding: var(--spacing-xxl) 0 var(--spacing-lg);
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}

.footer__brand {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.footer__logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.footer__logo img {
  height: 36px;
}

.footer__logo-text {
  color: #fff;
  font-family: var(--font-heading);
  font-size: 1.1rem;
}

.footer__desc {
  font-size: 0.9rem;
  line-height: 1.7;
  color: #999;
}

.footer__title {
  color: #fff;
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
}

.footer__links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.footer__link {
  color: #999;
  font-size: 0.9rem;
  transition: color var(--transition);
}

.footer__link:hover {
  color: var(--secondary);
}

.footer__bottom {
  border-top: 1px solid #333;
  padding-top: var(--spacing-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: #666;
}

.footer__social {
  display: flex;
  gap: var(--spacing-sm);
}

.footer__social-link {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: #333;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #999;
  transition: all var(--transition);
}

.footer__social-link:hover {
  background: var(--primary);
  color: #fff;
}

/* === 面包屑导航 === */
.breadcrumb {
  padding: var(--spacing-sm) 0;
  font-size: 0.875rem;
}

.breadcrumb__list {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.breadcrumb__item {
  color: var(--text-light);
}

.breadcrumb__item a {
  color: var(--text-light);
}

.breadcrumb__item a:hover {
  color: var(--primary);
}

.breadcrumb__separator {
  color: var(--border);
}

/* === 分页器 === */
.pagination {
  display: flex;
  justify-content: center;
  gap: var(--spacing-xs);
  margin-top: var(--spacing-xl);
}

.pagination__item {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--font-number);
  transition: all var(--transition);
}

.pagination__item:hover,
.pagination__item--active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

/* === 动画关键帧 === */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* 滚动触发动画类 */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.6s ease;
}

.animate-on-scroll--visible {
  opacity: 1;
  transform: translateY(0);
}

/* === 响应式设计（移动优先） === */

/* 平板端 (768px以下) */
@media (max-width: 768px) {
  html { font-size: 14px; }
  
  .nav__list { display: none; }
  .hamburger { display: flex; }
  
  /* 移动端导航菜单 */
  .nav--mobile {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    background: var(--bg);
    padding: var(--spacing-xxl) var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    transition: right var(--transition);
    z-index: 9998;
  }
  
  .nav--mobile.active {
    right: 0;
  }
  
  .nav--mobile .nav__list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
  }
  
  .hero__title { font-size: 2rem; }
  .hero__subtitle { font-size: 1rem; }
  
  .advantages__grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .courses-grid {
    grid-template-columns: 1fr;
  }
  
  .footer__grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
  }
  
  .footer__bottom {
    flex-direction: column;
    gap: var(--spacing-sm);
    text-align: center;
  }
  
  .timeline::before { left: 20px; }
  .timeline__item { flex-direction: column !important; align-items: flex-start; padding-left: 50px; }
  .timeline__content { width: 100%; }
  .timeline__dot { left: 20px; }
  
  .masonry-gallery { columns: 2; }
  
  .cta-banner__form {
    flex-direction: column;
  }
  
  .header__search { display: none; }
}

/* 小屏手机 (480px以下) */
@media (max-width: 480px) {
  .advantages__grid {
    grid-template-columns: 1fr;
  }
  
  .masonry-gallery { columns: 1; }
  
  .hero__actions {
    flex-direction: column;
    align-items: center;
  }
  
  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.5rem; }
}

/* 大屏桌面 (1400px以上) */
@media (min-width: 1400px) {
  .container {
    max-width: 1320px;
  }
}

/* === 工具类 === */
.text-center { text-align: center; }
.text-primary { color: var(--primary); }
.text-secondary { color: var(--secondary); }
.text-light { color: var(--text-light); }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.hidden { display: none; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}