/* ============================================================
 * AI课程系统官网 — 独立域名 lesson.sissiegao.com
 * 视觉来源: 复用 admin.css 设计令牌,米白工具系风格
 * ============================================================ */

/* 页面专属变量:在 admin.css 令牌基础上微调 */
:root {
  --ls-bg: #f7f5f0;
  --ls-card: #ffffff;
  --ls-line: #e8e5df;
  --ls-ink: #2c2a26;
  --ls-sub: #7a756c;
  --ls-accent: #4f46e5;
  --ls-accent2: #0ea5a4;
  --ls-accent-soft: rgba(79, 70, 229, .07);
  --ls-accent-line: rgba(79, 70, 229, .14);
  --ls-radius: 16px;
  --ls-radius-lg: 24px;
  --ls-shadow: 0 1px 2px rgba(44, 42, 38, .03), 0 4px 16px rgba(44, 42, 38, .05);
  --ls-shadow-md: 0 2px 8px rgba(44, 42, 38, .05), 0 12px 40px rgba(44, 42, 38, .08);
}

body {
  background: var(--ls-bg);
  color: var(--ls-ink);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 15px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* 顶栏 */
.ls-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(247, 245, 240, .88);
  backdrop-filter: blur(20px) saturate(1.6);
  -webkit-backdrop-filter: blur(20px) saturate(1.6);
  border-bottom: 1px solid var(--ls-line);
}
.ls-header-inner {
  max-width: 1200px; margin: 0 auto; padding: 0 24px; height: 64px;
  display: flex; align-items: center; gap: 20px;
}
.ls-logo {
  display: flex; align-items: center; gap: 10px;
}
.ls-logo-mark {
  width: 34px; height: 34px; border-radius: 10px;
  background: linear-gradient(135deg, var(--ls-accent), var(--ls-accent2));
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-size: 16px; font-weight: 800;
}
.ls-logo b { font-size: 17px; font-weight: 700; letter-spacing: -.02em; }
.ls-logo small { font-size: 11px; color: var(--ls-sub); font-weight: 400; margin-left: 2px; }
.ls-nav { display: flex; gap: 4px; margin-left: auto; }
.ls-nav a {
  padding: 8px 16px; border-radius: 999px; font-size: 14px; font-weight: 500;
  color: var(--ls-sub); text-decoration: none; transition: all .15s;
}
.ls-nav a:hover { color: var(--ls-ink); background: var(--ls-accent-soft); }
.ls-nav a.ls-nav-cta {
  color: #fff; background: var(--ls-accent); font-weight: 600;
}
.ls-nav a.ls-nav-cta:hover { background: #4338ca; }

/* Hero */
.ls-hero {
  max-width: 1200px; margin: 0 auto; padding: 60px 24px 60px;
}
.ls-hero-inner {
  display: flex; gap: 48px; align-items: center;
}
.ls-hero-text { flex: 1; }
.ls-hero-badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 14px; border-radius: 999px;
  background: var(--ls-accent-soft); color: var(--ls-accent);
  font-size: 13px; font-weight: 600; margin-bottom: 20px;
}
.ls-hero-badge::before { content: ''; width: 6px; height: 6px; border-radius: 50%; background: currentColor; }
.ls-hero h1 {
  font-size: 42px; font-weight: 800; letter-spacing: -.03em; line-height: 1.2;
  margin-bottom: 20px;
}
.ls-hero h1 em {
  font-style: normal;
  background: linear-gradient(135deg, var(--ls-accent), var(--ls-accent2));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.ls-hero p {
  font-size: 17px; color: var(--ls-sub); max-width: 480px; margin-bottom: 32px;
}
.ls-hero-cta {
  display: flex; gap: 14px; flex-wrap: wrap;
}
.ls-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 28px; border-radius: 999px; font-size: 15px; font-weight: 600;
  text-decoration: none; transition: all .2s; border: none; cursor: pointer;
}
.ls-btn-primary {
  background: var(--ls-accent); color: #fff;
  box-shadow: 0 4px 14px rgba(79, 70, 229, .3);
}
.ls-btn-primary:hover { background: #4338ca; transform: translateY(-1px); box-shadow: 0 6px 20px rgba(79, 70, 229, .4); }
.ls-btn-outline {
  background: transparent; color: var(--ls-ink);
  border: 1.5px solid var(--ls-line);
}
.ls-btn-outline:hover { border-color: var(--ls-accent); color: var(--ls-accent); }

/* 截图区 */
.ls-hero-shots {
  flex: 0 0 520px;
  display: flex; flex-direction: column; gap: 16px;
}
.ls-shot {
  border-radius: var(--ls-radius-lg); overflow: hidden;
  box-shadow: var(--ls-shadow-md); border: 1px solid var(--ls-line);
  background: var(--ls-card);
}
.ls-shot img { width: 100%; display: block; }
.ls-shot-cap {
  padding: 10px 16px; font-size: 12px; color: var(--ls-sub);
  background: var(--ls-card); border-top: 1px solid var(--ls-line);
  text-align: center;
}

/* 通用区块 */
.ls-section {
  max-width: 1200px; margin: 0 auto; padding: 80px 24px;
}
.ls-section-head {
  text-align: center; margin-bottom: 56px;
}
.ls-section-tag {
  display: inline-block; padding: 5px 14px; border-radius: 999px;
  background: var(--ls-accent-soft); color: var(--ls-accent);
  font-size: 13px; font-weight: 600; margin-bottom: 16px;
}
.ls-section h2 {
  font-size: 32px; font-weight: 800; letter-spacing: -.02em; margin-bottom: 12px;
}
.ls-section-head p {
  font-size: 16px; color: var(--ls-sub); max-width: 520px; margin: 0 auto;
}

/* 痛点区 */
.ls-pain-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px;
}
.ls-pain-card {
  background: var(--ls-card); border-radius: var(--ls-radius);
  padding: 28px 24px; border: 1px solid var(--ls-line);
  box-shadow: var(--ls-shadow);
  transition: all .2s;
}
.ls-pain-card:hover { transform: translateY(-2px); box-shadow: var(--ls-shadow-md); }
.ls-pain-icon {
  width: 40px; height: 40px; border-radius: 10px;
  background: #fee2e2; color: #dc2626;
  display: flex; align-items: center; justify-content: center;
  font-size: 18px; margin-bottom: 16px;
}
.ls-pain-card h3 { font-size: 16px; font-weight: 700; margin-bottom: 8px; }
.ls-pain-card p { font-size: 14px; color: var(--ls-sub); line-height: 1.6; }

/* 功能卡片 */
.ls-feat-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px;
}
.ls-feat-card {
  background: var(--ls-card); border-radius: var(--ls-radius);
  padding: 32px 28px; border: 1px solid var(--ls-line);
  box-shadow: var(--ls-shadow);
  transition: all .2s;
}
.ls-feat-card:hover { transform: translateY(-2px); box-shadow: var(--ls-shadow-md); }
.ls-feat-icon {
  width: 44px; height: 44px; border-radius: 12px;
  background: var(--ls-accent-soft); color: var(--ls-accent);
  display: flex; align-items: center; justify-content: center;
  font-size: 20px; margin-bottom: 20px;
}
.ls-feat-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 10px; }
.ls-feat-card p { font-size: 14.5px; color: var(--ls-sub); line-height: 1.7; margin-bottom: 16px; }
.ls-feat-list {
  list-style: none; padding: 0; margin: 0;
}
.ls-feat-list li {
  font-size: 13.5px; color: var(--ls-sub); padding: 4px 0;
  display: flex; align-items: center; gap: 8px;
}
.ls-feat-list li::before {
  content: '✓'; color: var(--ls-accent2); font-weight: 700; flex: none;
}

/* AI 亮点区 */
.ls-ai-section {
  background: linear-gradient(180deg, var(--ls-bg) 0%, #eef2ff 50%, var(--ls-bg) 100%);
  border-top: 1px solid var(--ls-line); border-bottom: 1px solid var(--ls-line);
}
.ls-ai-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center;
}
.ls-ai-visual {
  background: var(--ls-card); border-radius: var(--ls-radius-lg);
  border: 1px solid var(--ls-line); box-shadow: var(--ls-shadow-md);
  padding: 32px; position: relative; overflow: hidden;
}
.ls-ai-visual::before {
  content: ''; position: absolute; top: -40%; right: -40%;
  width: 80%; height: 80%; border-radius: 50%;
  background: radial-gradient(circle, rgba(79, 70, 229, .08) 0%, transparent 70%);
}
.ls-ai-chat {
  display: flex; flex-direction: column; gap: 12px;
}
.ls-ai-msg {
  padding: 12px 16px; border-radius: 14px; font-size: 13.5px; line-height: 1.6;
  max-width: 85%;
}
.ls-ai-msg-user {
  background: var(--ls-accent-soft); color: var(--ls-ink); align-self: flex-end;
  border-bottom-right-radius: 4px;
}
.ls-ai-msg-bot {
  background: #f0fdf4; color: #166534; align-self: flex-start;
  border-bottom-left-radius: 4px; border: 1px solid #bbf7d0;
}
.ls-ai-msg-tag {
  display: inline-block; font-size: 11px; color: var(--ls-accent2);
  background: rgba(14, 165, 164, .1); padding: 2px 8px; border-radius: 999px;
  margin-bottom: 6px; font-weight: 600;
}
.ls-ai-content h2 { font-size: 28px; font-weight: 800; margin-bottom: 16px; letter-spacing: -.02em; }
.ls-ai-content > p { font-size: 16px; color: var(--ls-sub); margin-bottom: 24px; line-height: 1.7; }
.ls-ai-points {
  list-style: none; padding: 0; margin: 0;
}
.ls-ai-points li {
  display: flex; gap: 12px; padding: 10px 0; font-size: 15px;
}
.ls-ai-points li .ls-ai-point-icon {
  width: 24px; height: 24px; border-radius: 6px; flex: none;
  background: var(--ls-accent-soft); color: var(--ls-accent);
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 700; margin-top: 2px;
}
.ls-ai-points li div b { display: block; font-size: 15px; font-weight: 600; margin-bottom: 2px; }
.ls-ai-points li div span { font-size: 13.5px; color: var(--ls-sub); }

/* 差异化能力 */
.ls-diff-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px;
}
.ls-diff-card {
  background: var(--ls-card); border-radius: var(--ls-radius);
  padding: 28px 24px; border: 1px solid var(--ls-line);
  box-shadow: var(--ls-shadow); text-align: center;
}
.ls-diff-icon {
  width: 48px; height: 48px; border-radius: 14px; margin: 0 auto 18px;
  display: flex; align-items: center; justify-content: center; font-size: 22px;
}
.ls-diff-icon-1 { background: #dbeafe; color: #2563eb; }
.ls-diff-icon-2 { background: #fef3c7; color: #d97706; }
.ls-diff-icon-3 { background: #d1fae5; color: #059669; }
.ls-diff-card h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.ls-diff-card p { font-size: 14px; color: var(--ls-sub); line-height: 1.6; }

/* 自行改造 */
.ls-diy-section {
  background: linear-gradient(180deg, var(--ls-bg) 0%, #f0fdf4 50%, var(--ls-bg) 100%);
  border-top: 1px solid var(--ls-line); border-bottom: 1px solid var(--ls-line);
}
.ls-diy-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px;
}
.ls-diy-card {
  background: var(--ls-card); border-radius: var(--ls-radius);
  padding: 28px 24px; border: 1px solid var(--ls-line);
  box-shadow: var(--ls-shadow); text-align: center;
  transition: all .2s;
}
.ls-diy-card:hover { transform: translateY(-2px); box-shadow: var(--ls-shadow-md); }
.ls-diy-icon {
  width: 48px; height: 48px; border-radius: 14px; margin: 0 auto 18px;
  background: #d1fae5; color: #059669;
  display: flex; align-items: center; justify-content: center; font-size: 22px;
}
.ls-diy-card h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.ls-diy-card p { font-size: 14px; color: var(--ls-sub); line-height: 1.6; }

/* 体验区 */
.ls-demo-section {
  background: var(--ls-card); border-top: 1px solid var(--ls-line); border-bottom: 1px solid var(--ls-line);
}
.ls-demo-inner {
  max-width: 800px; margin: 0 auto; text-align: center;
}
.ls-demo-inner h2 { font-size: 28px; font-weight: 800; margin-bottom: 12px; }
.ls-demo-inner > p { font-size: 16px; color: var(--ls-sub); margin-bottom: 32px; }
.ls-demo-links {
  display: flex; gap: 16px; justify-content: center; flex-wrap: wrap;
}
.ls-demo-link {
  display: flex; align-items: center; gap: 10px;
  padding: 16px 24px; border-radius: var(--ls-radius);
  border: 1.5px solid var(--ls-line); background: var(--ls-bg);
  text-decoration: none; color: var(--ls-ink); font-weight: 600; font-size: 15px;
  transition: all .2s;
}
.ls-demo-link:hover { border-color: var(--ls-accent); color: var(--ls-accent); transform: translateY(-1px); }
.ls-demo-link .ls-demo-arrow { color: var(--ls-sub); font-size: 13px; }

/* 底部 CTA */
.ls-cta-section {
  text-align: center; padding: 80px 24px;
}
.ls-cta-inner {
  max-width: 560px; margin: 0 auto;
  background: var(--ls-card); border-radius: var(--ls-radius-lg);
  border: 1px solid var(--ls-line); box-shadow: var(--ls-shadow-md);
  padding: 48px 40px;
}
.ls-cta-inner h2 { font-size: 28px; font-weight: 800; margin-bottom: 12px; }
.ls-cta-inner > p { font-size: 15px; color: var(--ls-sub); margin-bottom: 32px; }
.ls-cta-wechat {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 14px 32px; border-radius: 999px;
  background: #07c160; color: #fff; font-size: 16px; font-weight: 600;
  text-decoration: none; transition: all .2s; border: none; cursor: pointer;
}
.ls-cta-wechat:hover { background: #06a050; transform: translateY(-1px); }

/* 微信弹窗 */
.ls-modal-mask {
  position: fixed; inset: 0; background: rgba(0,0,0,.5);
  display: none; align-items: center; justify-content: center; z-index: 100;
  backdrop-filter: blur(4px);
}
.ls-modal-mask.on { display: flex; }
.ls-modal {
  background: var(--ls-card); border-radius: var(--ls-radius-lg);
  padding: 40px; text-align: center; max-width: 360px; width: 90%;
  box-shadow: 0 24px 60px rgba(0,0,0,.2);
}
.ls-modal h3 { font-size: 20px; font-weight: 700; margin-bottom: 8px; }
.ls-modal p { font-size: 14px; color: var(--ls-sub); margin-bottom: 24px; }
.ls-modal-qr {
  width: 200px; height: 200px; margin: 0 auto 24px;
  background: #f0f0f0; border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  color: var(--ls-sub); font-size: 13px;
}
.ls-modal-qr img { width: 100%; height: 100%; object-fit: contain; border-radius: 12px; }
.ls-modal-close {
  padding: 10px 24px; border-radius: 999px;
  border: 1px solid var(--ls-line); background: transparent;
  color: var(--ls-sub); font-size: 14px; cursor: pointer;
}

/* 页脚 */
.ls-footer {
  border-top: 1px solid var(--ls-line); padding: 32px 24px;
  text-align: center; font-size: 13px; color: var(--ls-sub);
}
.ls-footer a { color: var(--ls-sub); text-decoration: none; }
.ls-footer a:hover { color: var(--ls-ink); }

/* 响应式 */
@media (max-width: 900px) {
  .ls-hero h1 { font-size: 32px; }
  .ls-pain-grid { grid-template-columns: repeat(2, 1fr); }
  .ls-feat-grid { grid-template-columns: 1fr; }
  .ls-ai-grid { grid-template-columns: 1fr; }
  .ls-diff-grid { grid-template-columns: 1fr; }
  .ls-diy-grid { grid-template-columns: 1fr; }
  .ls-hero-inner { flex-direction: column; }
  .ls-hero-shots { flex: 0 0 auto; width: 100%; max-width: 480px; }
}
@media (max-width: 640px) {
  .ls-nav { display: none; }
  .ls-hero h1 { font-size: 28px; }
  .ls-hero p { font-size: 15px; }
  .ls-pain-grid { grid-template-columns: 1fr; }
  .ls-section h2 { font-size: 24px; }
  .ls-hero-cta { flex-direction: column; align-items: center; }
  .ls-btn { width: 100%; max-width: 280px; justify-content: center; }
}