/* 品牌介绍页样式 —— 移动优先响应式 */
:root {
  --brand: #e8590c;          /* 品牌橙 */
  --brand-dark: #c2410c;
  --ink: #1f2328;
  --muted: #667085;
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --line: #e5e7eb;
  --radius: 12px;
  --shadow: 0 6px 24px rgba(31, 35, 40, .08);
  --nav-h: 60px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  color: var(--ink);
  line-height: 1.7;
  background: var(--bg);
}
a { color: inherit; text-decoration: none; }
h1, h2, h3 { line-height: 1.3; }

/* ===== 导航 ===== */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  background: rgba(255, 255, 255, .92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
  z-index: 100;
}
.nav-inner {
  max-width: 1080px;
  height: 100%;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.brand { font-size: 20px; font-weight: 800; letter-spacing: 1px; }
.brand span { color: var(--brand); }
.nav-links {
  display: none;
  flex-direction: column;
  position: absolute;
  top: var(--nav-h); left: 0; right: 0;
  background: #fff;
  border-bottom: 1px solid var(--line);
  padding: 8px 20px 16px;
  gap: 4px;
}
.nav-links.open { display: flex; }
.nav-links a { padding: 8px 4px; font-size: 15px; color: var(--muted); }
.nav-links a:hover, .nav-links a.active { color: var(--brand); }
.nav-links .nav-login { color: var(--brand); font-weight: 600; }
.nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px; height: 40px;
  background: none; border: 0; cursor: pointer;
}
.nav-toggle span {
  display: block; height: 2px; width: 22px;
  background: var(--ink); margin: 0 auto;
  transition: .25s;
}
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ===== 通用区块 ===== */
.hero {
  padding: calc(var(--nav-h) + 72px) 20px 72px;
  text-align: center;
  background:
    radial-gradient(1000px 400px at 20% -10%, rgba(232, 89, 12, .14), transparent),
    radial-gradient(800px 360px at 90% 0%, rgba(232, 89, 12, .10), transparent),
    var(--bg-alt);
}
.hero h1 { font-size: 40px; font-weight: 800; }
.hero p { margin: 16px auto 28px; max-width: 560px; color: var(--muted); font-size: 18px; }
.hero-actions { display: flex; justify-content: center; gap: 14px; flex-wrap: wrap; }

.section { padding: 64px 20px; }
.section-alt { background: var(--bg-alt); }
.section-inner { max-width: 1080px; margin: 0 auto; }
.section h2 { text-align: center; font-size: 28px; font-weight: 800; }
.section .lead { text-align: center; color: var(--muted); margin: 12px auto 36px; max-width: 640px; }

/* ===== 按钮 ===== */
.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 600;
  transition: .2s;
}
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); transform: translateY(-1px); }
.btn-ghost { border: 1.5px solid var(--brand); color: var(--brand); }
.btn-ghost:hover { background: rgba(232, 89, 12, .08); }

/* ===== 卡片 ===== */
.about-grid { display: grid; gap: 20px; }
.about-card, .feature-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}
.about-card h3 { margin-bottom: 8px; color: var(--brand-dark); }
.about-card p { color: var(--muted); }

.feature-grid { display: grid; gap: 20px; }
.feature-card { text-align: center; transition: .2s; }
.feature-card:hover { transform: translateY(-4px); border-color: var(--brand); }
.feature-icon { font-size: 40px; margin-bottom: 12px; }
.feature-card h3 { margin-bottom: 8px; }
.feature-card p { color: var(--muted); font-size: 15px; }

/* ===== 商户链路 ===== */
.chain {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 12px;
  margin-bottom: 28px;
}
.chain-node {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
}
.chain-node h3 { color: var(--brand); margin-bottom: 6px; }
.chain-node p { color: var(--muted); font-size: 14px; }
.chain-arrow { text-align: center; color: var(--brand); font-size: 22px; }

.flow { list-style: none; counter-reset: step; }
.flow li {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 0;
  border-bottom: 1px dashed var(--line);
  counter-increment: step;
}
.flow li::before {
  content: counter(step);
  width: 28px; height: 28px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--brand);
  color: #fff;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
}
.flow li span { font-weight: 700; min-width: 88px; color: var(--ink); }

/* ===== 管理后台模块 ===== */
.module-list {
  list-style: none;
  display: grid;
  gap: 12px;
  margin-bottom: 32px;
}
.module-list li {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px 16px;
  font-size: 15px;
}
.module-list li::before { content: "✓ "; color: var(--brand); font-weight: 700; }
#admin .btn { display: inline-block; }

/* ===== 联系 ===== */
.contact-grid { display: grid; gap: 20px; }
.contact-item {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
}
.contact-item h3 { color: var(--brand-dark); margin-bottom: 6px; }
.contact-item p { color: var(--muted); font-size: 14px; margin-bottom: 10px; }
.contact-item a { color: var(--brand); font-weight: 600; word-break: break-all; }

/* ===== 页脚 ===== */
.footer {
  border-top: 1px solid var(--line);
  text-align: center;
  padding: 24px 20px;
  color: var(--muted);
  font-size: 14px;
}

/* ===== 桌面端 ===== */
@media (min-width: 768px) {
  .nav-links {
    display: flex;
    flex-direction: row;
    position: static;
    background: none;
    border: 0;
    padding: 0;
    gap: 24px;
    align-items: center;
  }
  .nav-links a { padding: 0; }
  .nav-toggle { display: none; }

  .hero h1 { font-size: 52px; }
  .hero { padding-top: calc(var(--nav-h) + 96px); }

  .about-grid { grid-template-columns: repeat(3, 1fr); }
  .feature-grid { grid-template-columns: repeat(4, 1fr); }
  .contact-grid { grid-template-columns: repeat(2, 1fr); }

  .chain { flex-direction: row; align-items: center; }
  .chain-node { flex: 1; }
  .chain-arrow { padding: 0 4px; }

  .module-list { grid-template-columns: repeat(2, 1fr); }
}