/* 乐学星球官网 — 公共样式（全站共享：基础 / 导航 / 内页横幅 / 页脚）
 * 设计目标：1920×1080 全屏浏览器内整页可见，不出现滚动条
 * （内容区 max-width 1120px 居中，≥1120 宽度下布局一致，高度恒定）
 */
* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
  font-size: 14px;
  color: #1f2937;
  background: #ffffff;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; }

/* ===== Header ===== */
header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,0.95);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid #eef0f3;
}
.nav {
  max-width: 1120px; margin: 0 auto;
  padding: 6px 24px;
  display: flex; align-items: center; justify-content: space-between;
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand img { width: 32px; height: 32px; border-radius: 8px; box-shadow: 0 4px 10px rgba(99,102,241,.25); }
.brand-name { font-size: 16px; font-weight: 700; color: #111827; line-height: 1.3; }
.brand-sub { font-size: 11px; color: #6b7280; line-height: 1.3; }
nav ul { list-style: none; display: flex; gap: 22px; }
nav a { font-size: 13.5px; color: #4b5563; padding: 2px 0; transition: color .2s; }
nav a:hover { color: #6366f1; }
nav a.active { color: #6366f1; font-weight: 600; }

/* ===== 内页横幅 ===== */
.page-hero {
  background: linear-gradient(135deg, #eef2ff 0%, #f5f3ff 55%, #fdf4ff 100%);
  padding: 18px 24px 20px;
}
.page-hero-inner { max-width: 1120px; margin: 0 auto; }
.page-hero h1 { font-size: 25px; font-weight: 800; color: #111827; letter-spacing: -0.3px; line-height: 1.3; }
.page-hero p { margin-top: 3px; font-size: 13.5px; color: #4b5563; line-height: 1.5; }

/* ===== 浅灰底区块（contact 使用） ===== */
.gray-bg { background: #fafafa; }
.gray-bg .block { padding-top: 12px; padding-bottom: 14px; }

/* ===== 内容区 ===== */
.block { max-width: 1120px; margin: 0 auto; padding: 15px 24px; }
.section-title { margin-bottom: 12px; }
.section-title h2 { font-size: 20px; color: #111827; font-weight: 700; line-height: 1.3; }
.section-title p { margin-top: 2px; color: #6b7280; font-size: 13px; line-height: 1.5; }

/* ===== 正文双栏（协议 / 政策页，充分利用 1080P 横向空间） ===== */
.prose { column-count: 2; column-gap: 48px; }
.prose h2 {
  font-size: 14px; color: #111827; font-weight: 700;
  margin: 10px 0 4px; break-inside: avoid;
}
.prose h2:first-child { margin-top: 0; }
.prose p, .prose li { font-size: 13px; color: #4b5563; line-height: 1.55; margin-bottom: 4px; break-inside: avoid; }
.prose ul { padding-left: 17px; margin-bottom: 4px; }
.prose strong { color: #111827; }

/* ===== 卡片 ===== */
.card-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.card {
  padding: 13px 16px; background: #fff;
  border: 1px solid #eef0f3; border-radius: 13px;
  transition: transform .25s, box-shadow .25s, border-color .25s;
}
.card:hover { transform: translateY(-4px); box-shadow: 0 12px 32px rgba(0,0,0,.06); border-color: #e0e7ff; }
.card .icon {
  width: 32px; height: 32px; border-radius: 9px;
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, #eef2ff, #ede9fe);
  font-size: 16px; margin-bottom: 8px;
}
.card h3 { font-size: 14.5px; color: #111827; margin-bottom: 3px; line-height: 1.4; }
.card p { font-size: 12px; color: #6b7280; line-height: 1.55; }

/* ===== 联系我们卡片 ===== */
.contact-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.contact-card { padding: 10px 16px; background: #fff; border: 1px solid #eef0f3; border-radius: 11px; }
.contact-card h4 { font-size: 12px; color: #6b7280; margin-bottom: 1px; font-weight: 500; line-height: 1.4; }
.contact-card p { font-size: 13.5px; color: #111827; word-break: break-all; line-height: 1.5; }

/* ===== Footer ===== */
footer { background: #111827; color: #9ca3af; padding: 16px 24px 10px; }
.footer-inner { max-width: 1120px; margin: 0 auto; }
.footer-top {
  display: grid; grid-template-columns: 1.2fr 1fr 1fr; gap: 32px;
  padding-bottom: 10px; border-bottom: 1px solid #1f2937;
}
.footer-top h5 { color: #fff; font-size: 13px; margin-bottom: 6px; line-height: 1.4; }
.footer-top p, .footer-top li { font-size: 12px; line-height: 1.7; }
.footer-top ul { list-style: none; }
.footer-top a:hover { color: #fff; }
.footer-bottom { padding-top: 8px; text-align: center; font-size: 11.5px; color: #6b7280; }
.footer-bottom a { color: #9ca3af; }
.footer-bottom a:hover { color: #fff; }
.footer-bottom p { margin: 1px 0; }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .nav { flex-wrap: wrap; gap: 6px; }
  nav ul { gap: 14px; }
  .card-grid { grid-template-columns: repeat(2, 1fr); }
  .contact-grid { grid-template-columns: 1fr; }
  .prose { column-count: 1; }
  .footer-top { grid-template-columns: 1fr; gap: 14px; }
  .page-hero h1 { font-size: 21px; }
}