/* ============================================
   博雅公益视频站 · bycm1122.cn
   风格：暖灰 + 生命绿 · 衬线标题 · 视频大封面 · 移动优先
   ============================================ */

/* CSS 变量 */
:root {
  --color-bg: #F5F2ED;          /* 米白背景 */
  --color-bg-alt: #FAF7F2;       /* 浅米白 */
  --color-text: #2C2C2C;         /* 主文字 */
  --color-text-soft: #5A5A5A;    /* 次要文字 */
  --color-text-muted: #8B8680;   /* 辅助文字 */
  --color-primary: #3A3A3A;      /* 暖灰主色 */
  --color-accent: #5B7553;       /* 生命绿 */
  --color-accent-dark: #3F5A40;  /* 深绿 */
  --color-accent-light: #7A9471; /* 浅绿 */
  --color-border: #E5E0D8;       /* 边框 */
  --color-dark: #2C2C2C;         /* 深色块 */

  --font-serif: 'Noto Serif SC', 'Source Han Serif SC', 'Songti SC', 'STSong', serif;
  --font-sans: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;

  --space-xs: 8px;
  --space-sm: 16px;
  --space-md: 32px;
  --space-lg: 64px;
  --space-xl: 120px;

  --max-width: 1280px;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-primary);
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(2.5rem, 5vw, 4rem); }
h2 { font-size: clamp(2rem, 4vw, 3rem); }
h3 { font-size: clamp(1.4rem, 2.5vw, 1.8rem); }
h4 { font-size: 1.15rem; }

p {
  color: var(--color-text-soft);
}

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

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

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

ul, ol {
  list-style: none;
}

/* 容器 */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ============================================
   导航
   ============================================ */
.nav {
  position: sticky;
  top: 0;
  background: rgba(245, 242, 237, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: 100;
  border-bottom: 1px solid var(--color-border);
}

.nav-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 72px;
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--color-accent-dark);
  letter-spacing: 0.02em;
  display: flex;
  align-items: center;
  gap: 10px;
}

.nav-logo-mark {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-accent-light), var(--color-accent-dark));
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.85rem;
  font-weight: 600;
}

.nav-menu {
  display: flex;
  gap: 36px;
}

.nav-menu a {
  font-size: 0.95rem;
  color: var(--color-text-soft);
  font-weight: 500;
  position: relative;
  padding: 8px 0;
  transition: color var(--transition);
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--color-accent);
}

.nav-menu a.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-accent);
}

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--color-primary);
}

/* ============================================
   Hero
   ============================================ */
.hero {
  min-height: 82vh;
  display: flex;
  align-items: center;
  padding: var(--space-xl) 0;
  position: relative;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #F5F2ED 0%, #E8E2D5 100%);
  z-index: -1;
}

.hero-bg::before {
  content: '';
  position: absolute;
  top: 10%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(91, 117, 83, 0.12) 0%, transparent 70%);
  border-radius: 50%;
}

.hero-bg::after {
  content: '';
  position: absolute;
  bottom: -20%;
  left: -5%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(168, 192, 154, 0.15) 0%, transparent 70%);
  border-radius: 50%;
}

.hero-content {
  max-width: 820px;
  position: relative;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-accent-dark);
  letter-spacing: 0.1em;
  margin-bottom: var(--space-md);
  padding: 6px 14px;
  background: rgba(91, 117, 83, 0.1);
  border-radius: 999px;
}

.hero-eyebrow::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
}

.hero-slogan {
  font-size: clamp(2.8rem, 6.5vw, 5rem);
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.15;
  color: var(--color-primary);
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
}

.hero-slogan em {
  font-style: normal;
  color: var(--color-accent-dark);
  position: relative;
  display: inline-block;
}

.hero-slogan em::after {
  content: '';
  position: absolute;
  bottom: 0.08em;
  left: 0;
  right: 0;
  height: 0.15em;
  background: rgba(91, 117, 83, 0.22);
  z-index: -1;
  border-radius: 4px;
}

.hero-sub {
  font-size: 1.2rem;
  color: var(--color-text-soft);
  margin-bottom: var(--space-lg);
  max-width: 620px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  border-radius: 999px;
  font-weight: 500;
  font-size: 1rem;
  transition: all var(--transition);
  cursor: pointer;
}

.btn-primary {
  background: var(--color-accent-dark);
  color: white;
}

.btn-primary:hover {
  background: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(63, 90, 64, 0.25);
}

.btn-secondary {
  background: transparent;
  color: var(--color-primary);
  border: 1.5px solid var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent-dark);
}

/* ============================================
   Section 通用
   ============================================ */
.section {
  padding: var(--space-xl) 0;
}

.section-header {
  margin-bottom: var(--space-lg);
  max-width: 720px;
}

.section-eyebrow {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-sm);
}

.section-title {
  margin-bottom: var(--space-sm);
}

.section-sub {
  color: var(--color-text-soft);
  font-size: 1.1rem;
  line-height: 1.7;
}

/* ============================================
   使命愿景
   ============================================ */

/* ============================================
   项目卡片
   ============================================ */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-lg);
}

.project-card {
  position: relative;
  background: white;
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--transition);
  cursor: pointer;
  border: 1px solid var(--color-border);
}

.project-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.08);
  border-color: var(--color-accent-light);
}

.project-cover {
  aspect-ratio: 4 / 3;
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, #C9D4B8 0%, #5B7553 100%);
}

.project-cover::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 40%, rgba(0,0,0,0.5) 100%);
}

.project-cover-char {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-size: 5rem;
  color: rgba(255, 255, 255, 0.35);
  font-weight: 600;
}

.project-tag {
  position: absolute;
  top: 16px;
  left: 16px;
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-accent-dark);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  background: rgba(255, 255, 255, 0.95);
  padding: 6px 12px;
  border-radius: 999px;
  z-index: 2;
}

.project-info {
  padding: var(--space-md);
}

.project-title {
  font-size: 1.4rem;
  margin-bottom: 12px;
}

.project-desc {
  color: var(--color-text-soft);
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: var(--space-sm);
}

.project-stats {
  display: flex;
  gap: var(--space-md);
  padding-top: var(--space-sm);
  border-top: 1px solid var(--color-border);
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.project-stats strong {
  color: var(--color-accent-dark);
  font-weight: 600;
  margin-right: 4px;
}

/* ============================================
   视频墙
   ============================================ */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-md);
}

.video-card {
  cursor: pointer;
  transition: all var(--transition);
}

.video-thumb {
  aspect-ratio: 16 / 9;
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-sm);
  background: var(--color-dark);
}

.video-thumb-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #3A3A3A 0%, #5B7553 100%);
  transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.video-card:hover .video-thumb-bg {
  transform: scale(1.05);
}

.video-play {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2;
}

.video-play-icon {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.95);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-accent-dark);
  font-size: 1.4rem;
  transition: all var(--transition);
  padding-left: 4px;
}

.video-card:hover .video-play-icon {
  transform: scale(1.1);
  background: white;
}

.video-duration {
  position: absolute;
  bottom: 12px;
  right: 12px;
  background: rgba(0, 0, 0, 0.75);
  color: white;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 500;
  z-index: 2;
  font-variant-numeric: tabular-nums;
}

.video-meta {
  padding: var(--space-sm) 0;
}

.video-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.video-info {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  display: flex;
  gap: 12px;
}

.video-info span:not(:last-child)::after {
  content: '·';
  margin-left: 12px;
}

/* ============================================
   使命愿景（特色块）
   ============================================ */
.mission {
  background: linear-gradient(135deg, #3F5A40 0%, #2F4431 100%);
  color: white;
  padding: var(--space-xl) 0;
  position: relative;
  overflow: hidden;
}

.mission::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 700px;
  height: 700px;
  background: radial-gradient(circle, rgba(255,255,255,0.04) 0%, transparent 70%);
  border-radius: 50%;
}

.mission-quote {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 500;
  line-height: 1.4;
  color: white;
  max-width: 880px;
  margin-bottom: var(--space-md);
}

.mission-quote::before {
  content: '"';
  display: block;
  font-size: 4rem;
  color: var(--color-accent-light);
  line-height: 0.5;
  margin-bottom: var(--space-sm);
}

.mission-sub {
  color: rgba(255, 255, 255, 0.75);
  font-size: 1.1rem;
  max-width: 640px;
  line-height: 1.8;
}

/* ============================================
   CTA Section
   ============================================ */
.cta-section {
  background: var(--color-accent-dark);
  color: white;
  padding: var(--space-xl) 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.cta-section::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -10%;
  width: 700px;
  height: 700px;
  background: radial-gradient(circle, rgba(255,255,255,0.06) 0%, transparent 70%);
  border-radius: 50%;
}

.cta-title {
  color: white;
  font-size: clamp(2rem, 4vw, 3rem);
  margin-bottom: var(--space-md);
}

.cta-sub {
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: var(--space-lg);
  font-size: 1.1rem;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

.cta-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.cta-section .btn-primary {
  background: white;
  color: var(--color-accent-dark);
}

.cta-section .btn-primary:hover {
  background: var(--color-bg);
  transform: translateY(-2px);
}

.cta-section .btn-secondary {
  background: transparent;
  color: white;
  border-color: rgba(255, 255, 255, 0.35);
}

.cta-section .btn-secondary:hover {
  background: rgba(255,255,255,0.1);
  border-color: white;
  color: white;
}

/* ============================================
   合作伙伴 logo 墙
   ============================================ */
.logos {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--space-md);
}

.logo-item {
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: white;
  border-radius: var(--radius-sm);
  color: var(--color-text-soft);
  font-size: 0.95rem;
  font-weight: 500;
  border: 1px solid var(--color-border);
  transition: all var(--transition);
  padding: 0 16px;
  text-align: center;
}

.logo-item:hover {
  color: var(--color-accent);
  border-color: var(--color-accent-light);
  transform: translateY(-2px);
}

/* ============================================
   表单
   ============================================ */
.form-card {
  max-width: 640px;
  margin: 0 auto;
  background: white;
  padding: var(--space-lg);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

.form-row {
  margin-bottom: var(--space-md);
}

.form-label {
  display: block;
  font-size: 0.95rem;
  font-weight: 500;
  margin-bottom: 8px;
  color: var(--color-primary);
}

.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 1rem;
  color: var(--color-text);
  background: var(--color-bg);
  transition: all var(--transition);
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--color-accent);
  background: white;
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
  font-family: inherit;
}

.form-submit {
  width: 100%;
  padding: 14px;
  background: var(--color-accent-dark);
  color: white;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 500;
  transition: all var(--transition);
}

.form-submit:hover {
  background: var(--color-accent);
}

/* ============================================
   Footer
   ============================================ */
.footer {
  background: var(--color-dark);
  color: rgba(255,255,255,0.65);
  padding: var(--space-xl) 0 var(--space-md);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.footer-brand {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  color: white;
  margin-bottom: var(--space-sm);
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-desc {
  font-size: 0.95rem;
  line-height: 1.8;
  max-width: 320px;
  color: rgba(255,255,255,0.6);
}

.footer-title {
  color: white;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  font-family: var(--font-sans);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.footer-list li {
  margin-bottom: 10px;
}

.footer-list a {
  color: rgba(255,255,255,0.65);
  font-size: 0.95rem;
}

.footer-list a:hover {
  color: white;
}

.footer-bottom {
  padding-top: var(--space-md);
  border-top: 1px solid rgba(255,255,255,0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-sm);
  font-size: 0.85rem;
  color: rgba(255,255,255,0.5);
}

.footer-bottom a {
  color: rgba(255,255,255,0.7);
}

.footer-bottom a:hover {
  color: white;
}

/* ============================================
   移动端
   ============================================ */
@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    flex-direction: column;
    padding: var(--space-md) 24px;
    border-bottom: 1px solid var(--color-border);
    gap: 4px;
  }

  .nav-menu.open {
    display: flex;
  }

  .nav-menu a {
    padding: 12px 0;
    border-bottom: 1px solid var(--color-border);
  }

  .nav-menu a.active::after {
    display: none;
  }

  .nav-toggle {
    display: flex;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }

  .section {
    padding: var(--space-lg) 0;
  }

  .hero {
    min-height: 70vh;
  }

  .hero-actions {
    width: 100%;
  }

  .hero-actions .btn {
    flex: 1;
    justify-content: center;
  }

  .cta-buttons .btn {
    width: 100%;
    justify-content: center;
  }
}

/* ============================================
   动画
   ============================================ */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 视频详情页 */
.video-detail {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: var(--space-lg);
  margin-top: var(--space-lg);
}

@media (max-width: 900px) {
  .video-detail {
    grid-template-columns: 1fr;
  }
}

.video-player {
  aspect-ratio: 16 / 9;
  background: var(--color-dark);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  position: relative;
  overflow: hidden;
}

.video-sidebar {
  background: white;
  padding: var(--space-md);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

/* 公益项目详情 */
.article-content {
  max-width: 760px;
  margin: 0 auto;
  font-size: 1.05rem;
  line-height: 1.9;
  color: var(--color-text-soft);
}

.article-content h2 {
  margin-top: var(--space-lg);
  margin-bottom: var(--space-sm);
  font-size: 1.6rem;
}

.article-content p {
  margin-bottom: var(--space-md);
}

.article-content blockquote {
  border-left: 3px solid var(--color-accent);
  padding-left: var(--space-md);
  margin: var(--space-md) 0;
  color: var(--color-primary);
  font-family: var(--font-serif);
  font-style: italic;
}