/* ===== 设计规范:色彩体系 ===== */
:root {
  /* 品牌色(对齐 logo #4A90D9) */
  --primary: #4A90D9;
  --primary-dark: #3A7BC8;
  --primary-light: #EFF6FF;
  --accent: #38BDF8;

  /* 中性色 */
  --text: #1A2B4A;
  --text-secondary: #5A6A85;
  --text-muted: #8B95A7;

  /* 背景 */
  --bg: #FFFFFF;
  --bg-alt: #F7F9FC;
  --bg-dark: #0F172A;

  /* 边框与阴影 */
  --border: #E2E8F0;
  --border-light: #EDF2F7;
  --shadow-sm: 0 1px 3px rgba(26,43,74,0.06);
  --shadow-md: 0 4px 16px rgba(26,43,74,0.08);
  --shadow-lg: 0 12px 32px rgba(26,43,74,0.12);

  /* 圆角 */
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 20px;
  --radius-full: 999px;
}

/* ===== 基础 ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 72px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--text);
  line-height: 1.7;
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

a { color: var(--primary); text-decoration: none; }
a:focus-visible, button:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; }

/* ===== 导航 ===== */
.nav {
  position: sticky; top: 0; z-index: 100; height: 64px;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s, box-shadow 0.3s;
}
.nav.scrolled { border-bottom-color: var(--border); box-shadow: var(--shadow-sm); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { display: flex; align-items: center; }
.logo img { height: 40px; width: auto; display: block; }

.menu { display: flex; gap: 32px; }
.menu a {
  color: var(--text-secondary); font-size: 14px; font-weight: 500;
  position: relative; transition: color 0.2s; padding: 4px 0;
}
.menu a:hover, .menu a.active { color: var(--primary); }
.menu a.active::after {
  content: ''; position: absolute; bottom: -2px; left: 0; right: 0;
  height: 2px; background: var(--primary); border-radius: 1px;
}
.menu-toggle { display: none; background: none; border: none; font-size: 22px; cursor: pointer; color: var(--text); }

/* ===== Hero ===== */
.hero {
  text-align: center;
  padding: 72px 24px 64px;
  position: relative; overflow: hidden;
  background: linear-gradient(180deg, #EBF4FF 0%, #F7F9FC 60%, #FFFFFF 100%);
}
.hero::before {
  content: ''; position: absolute; inset: 0; pointer-events: none;
  background-image:
    radial-gradient(circle at 20% 30%, rgba(74,144,217,0.08) 0%, transparent 50%),
    radial-gradient(circle at 80% 70%, rgba(56,189,248,0.06) 0%, transparent 50%);
}

.avatar {
  width: clamp(110px, 14vw, 160px);
  height: clamp(110px, 14vw, 160px);
  margin: 0 auto 24px;
  border-radius: 50%;
  background: var(--primary) url("../img/avatar.jpg") center / cover no-repeat;
  border: 4px solid #fff;
  box-shadow: 0 8px 24px rgba(74,144,217,0.2);
  position: relative;
}
.hero-name { font-size: 44px; font-weight: 800; letter-spacing: -0.02em; margin-bottom: 8px; }
.hero-title { font-size: 20px; color: var(--primary); font-weight: 600; margin-bottom: 16px; }
.hero-desc { max-width: 560px; margin: 0 auto 32px; color: var(--text-secondary); font-size: 16px; line-height: 1.7; }
.hero-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; margin-bottom: 48px; }

.hero-stats { display: flex; justify-content: center; gap: 48px; flex-wrap: wrap; }
.stat { display: flex; flex-direction: column; align-items: center; }
.stat-num { font-size: 28px; font-weight: 800; color: var(--primary); }
.stat-label { font-size: 13px; color: var(--text-muted); margin-top: 4px; }

/* ===== 按钮 ===== */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 12px 32px; border-radius: var(--radius-full);
  font-size: 15px; font-weight: 600; cursor: pointer;
  border: none; transition: all 0.25s cubic-bezier(0.4,0,0.2,1);
  text-decoration: none; gap: 8px;
}
.btn-primary { background: var(--primary); color: #fff; box-shadow: 0 2px 8px rgba(74,144,217,0.3); }
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-2px); box-shadow: 0 6px 20px rgba(74,144,217,0.35); }
.btn-primary:active { transform: translateY(0); }
.btn-outline { background: transparent; color: var(--primary); border: 1.5px solid var(--primary); }
.btn-outline:hover { background: var(--primary-light); }
.btn-sm { padding: 8px 20px; font-size: 13px; }

/* ===== 区块 ===== */
.section { padding: 80px 24px; }
.section-alt { background: var(--bg-alt); }
.section-title {
  text-align: center;
  font-size: 32px; font-weight: 700; letter-spacing: -0.01em;
  margin-bottom: 8px;
}
.section-sub { text-align: center; color: var(--text-secondary); margin-bottom: 40px; }

/* 关于我 */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; max-width: 960px; margin: 0 auto; }
.about-card {
  background: var(--bg);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow-sm);
}
.about-card h3 { margin-bottom: 16px; font-size: 18px; }

.info-list { list-style: none; }
.info-list li { display: flex; padding: 8px 0; border-bottom: 1px solid var(--border-light); }
.info-list li:last-child { border-bottom: none; }
.info-list .label { width: 72px; color: var(--text-secondary); flex-shrink: 0; }

/* 技能标签 */
.tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.tag {
  padding: 4px 14px; border-radius: var(--radius-full); font-size: 13px;
  background: var(--primary-light); color: var(--primary); font-weight: 500;
}

/* 时间线 */
.timeline { position: relative; padding-left: 28px; }.timeline::before {
  content: ''; position: absolute; left: 7px; top: 8px; bottom: 8px;
  width: 2px; background: var(--border);
}
.timeline-item { position: relative; margin-bottom: 24px; }
.timeline-item:last-child { margin-bottom: 0; }
.timeline-item::before {
  content: ''; position: absolute; left: -28px; top: 6px;
  width: 16px; height: 16px; border-radius: 50%; background: #fff;
  border: 3px solid var(--primary); box-shadow: 0 0 0 4px var(--primary-light);
}
.timeline-time { font-size: 13px; color: var(--primary); font-weight: 600; margin-bottom: 4px; }
.timeline-title { font-size: 16px; font-weight: 600; color: var(--text); margin-bottom: 4px; }
.timeline-desc { font-size: 14px; color: var(--text-secondary); line-height: 1.6; }
.timeline-list { margin-top: 4px; padding-left: 18px; }
.timeline-list li { font-size: 14px; color: var(--text-secondary); line-height: 1.8; }

/* 信奥教学 */
.teaching-card {
  max-width: 760px; margin: 0 auto;
  background: var(--bg); border: 1px solid var(--border-light);
  border-radius: var(--radius); padding: 36px 32px;
  box-shadow: var(--shadow-sm); text-align: center;
  font-size: 16px; color: var(--text-secondary); line-height: 1.9;
}

/* 模拟赛出题 */
.contest-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; max-width: 760px; margin: 0 auto; }
.badge {
  display: inline-block; margin-top: 12px; padding: 3px 12px;
  border-radius: var(--radius-full); font-size: 12px; font-weight: 600;
}
.badge-pending { background: var(--primary-light); color: var(--primary); border: 1px solid var(--border); }

@media (max-width: 600px) {
  .contest-grid { grid-template-columns: 1fr; }
}

/* ===== 卡片(服务能力 / toB) ===== */
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.card {
  background: var(--bg); border: 1px solid var(--border-light);
  border-radius: var(--radius); padding: 32px 28px;
  box-shadow: var(--shadow-sm); transition: all 0.3s cubic-bezier(0.4,0,0.2,1);
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--border); }
.card-icon {
  width: 48px; height: 48px; border-radius: 12px;
  background: linear-gradient(135deg, var(--primary-light), #fff);
  color: var(--primary); display: flex; align-items: center; justify-content: center;
  font-size: 20px; font-weight: 700; margin-bottom: 20px;
  border: 1px solid var(--border-light);
}
.card h3 { font-size: 17px; font-weight: 600; margin-bottom: 8px; }
.card p { color: var(--text-secondary); font-size: 14px; }

/* toB 合作方向/优势卡片(左色条区分) */
.coop-grid { grid-template-columns: repeat(3, 1fr); }
.coop-card { border-top: 3px solid var(--primary); }
.coop-badge {
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--primary); color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-size: 15px; font-weight: 700; margin-bottom: 16px;
}

/* 合作流程步骤条 */
.coop-block { max-width: 960px; margin: 0 auto 48px; }
.coop-block h3 { font-size: 20px; margin-bottom: 20px; padding-left: 12px; border-left: 4px solid var(--primary); }
.steps { display: flex; justify-content: space-between; gap: 16px; position: relative; flex-wrap: wrap; }
.step { flex: 1; min-width: 140px; text-align: center; position: relative; }
.step-num {
  width: 40px; height: 40px; border-radius: 50%; background: var(--primary);
  color: #fff; display: flex; align-items: center; justify-content: center;
  font-size: 16px; font-weight: 700; margin: 0 auto 12px; position: relative; z-index: 1;
}
.step:not(:last-child)::after {
  content: ''; position: absolute; top: 20px; left: calc(50% + 24px);
  right: calc(-50% + 24px); height: 2px; background: var(--border);
}
.step-title { font-size: 15px; font-weight: 600; color: var(--text); margin-bottom: 4px; }
.step-desc { font-size: 13px; color: var(--text-muted); line-height: 1.5; }

/* ===== 联系 ===== */
.contact-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; max-width: 860px; margin: 0 auto; }
.contact-item {
  display: block; text-align: center;
  background: var(--bg); border: 1px solid var(--border-light);
  border-radius: var(--radius); padding: 28px 16px;
  color: var(--text); box-shadow: var(--shadow-sm);
  transition: transform 0.2s, box-shadow 0.2s;
}
.contact-item:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); color: var(--primary); }
.contact-icon { font-size: 24px; display: block; margin-bottom: 8px; }
.contact-item h4 { font-size: 16px; font-weight: 600; margin-bottom: 8px; }
.contact-value { color: var(--text-secondary); font-size: 14px; }
.qr-placeholder {
  width: 120px; height: 120px; margin: 8px auto;
  border: 1px dashed var(--border); border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  color: var(--text-muted); font-size: 12px;
  background: var(--bg-alt);
}

/* ===== 页脚 ===== */
.footer { background: var(--bg-dark); color: #94A3B8; padding: 48px 24px 0; }
.footer-grid {
  display: grid; grid-template-columns: 1.5fr 1fr 1fr;
  gap: 40px; max-width: 1120px; margin: 0 auto; padding-bottom: 40px;
}
.footer-brand img { height: 32px; width: auto; display: block; margin-bottom: 12px; }
.footer-brand p { font-size: 14px; color: #94A3B8; max-width: 280px; }
.footer-links h5, .footer-contact h5 { color: #E2E8F0; font-size: 14px; font-weight: 600; margin-bottom: 12px; }
.footer-links a, .footer-contact a { display: block; color: #94A3B8; font-size: 14px; margin-bottom: 8px; transition: color 0.2s; }
.footer-links a:hover, .footer-contact a:hover { color: #fff; }
.footer-contact p { font-size: 14px; margin-bottom: 8px; }
.footer-bottom {
  border-top: 1px solid rgba(148,163,184,0.15);
  text-align: center; padding: 20px 0; font-size: 13px; color: #64748B;
}

/* 回到顶部 */
.back-to-top {
  position: fixed; right: 24px; bottom: 24px; z-index: 99;
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--primary); color: #fff; border: none;
  font-size: 18px; cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0; visibility: hidden; transform: translateY(8px);
  transition: all 0.3s;
}
.back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--primary-dark); }

/* ===== 滚动入场动画 ===== */
.fade-in-up {
  opacity: 0; transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in-up.visible { opacity: 1; transform: translateY(0); }

/* ===== 响应式断点 ===== */
@media (max-width: 900px) {
  .card-grid, .coop-grid { grid-template-columns: repeat(2, 1fr); }
  .contact-grid { grid-template-columns: repeat(2, 1fr); }
  .about-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .hero { padding: 56px 20px 48px; }
  .hero-name { font-size: 30px; }
  .hero-stats { gap: 32px; }
  .stat-num { font-size: 24px; }
  .section { padding: 56px 20px; }

  .menu {
    display: none; position: absolute; top: 64px; left: 0; right: 0;
    background: #fff; flex-direction: column; padding: 16px 24px; gap: 16px;
    border-bottom: 1px solid var(--border); box-shadow: var(--shadow-md);
  }
  .menu.open { display: flex; }
  .menu-toggle { display: block; }
  .menu a.active::after { display: none; }

  .card-grid, .coop-grid, .contact-grid { grid-template-columns: 1fr; }
  .steps { flex-direction: column; align-items: flex-start; }
  .step { text-align: left; display: flex; align-items: flex-start; gap: 16px; }
  .step-num { margin: 0; flex-shrink: 0; }
  .step:not(:last-child)::after { display: none; }
  .step-title, .step-desc { text-align: left; }
  .footer-grid { grid-template-columns: 1fr; gap: 24px; }
}