/* ===== 全局重置 & 变量 ===== */
:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #a5b4fc;
  --secondary: #06b6d4;
  --accent: #f59e0b;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --radius: 20px;
  --radius-sm: 12px;
  --shadow: 0 10px 25px -5px rgba(0,0,0,0.08), 0 8px 10px -6px rgba(0,0,0,0.02);
  --shadow-hover: 0 20px 40px -10px rgba(99,102,241,0.25);
  --transition: 0.3s cubic-bezier(.4,0,.2,1);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  padding-top: 64px; /* 为固定导航留空 */
}
a { color: var(--primary); text-decoration: none; }
img { max-width: 100%; display: block; }
button { cursor: pointer; font-family: inherit; }
input, button { outline: none; }

/* ===== 头部导航 (PWA 风格) ===== */
.app-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: rgba(255,255,255,0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}
.app-header.scrolled {
  background: rgba(255,255,255,0.95);
  box-shadow: 0 2px 20px rgba(0,0,0,0.06);
}
.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  font-size: 1.6rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.logo span { font-weight: 400; opacity: 0.8; }
.nav-links {
  display: flex;
  gap: 28px;
}
.nav-links a {
  font-weight: 500;
  color: var(--text-secondary);
  transition: var(--transition);
  position: relative;
  padding: 4px 0;
}
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 0; height: 2px;
  background: var(--primary);
  border-radius: 4px;
  transition: var(--transition);
}
.nav-links a:hover, .nav-links a.active { color: var(--primary); }
.nav-links a.active::after, .nav-links a:hover::after { width: 100%; }
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  padding: 6px;
  border-radius: 8px;
}
.menu-toggle span {
  display: block;
  width: 24px; height: 2.5px;
  background: var(--text);
  border-radius: 4px;
  transition: var(--transition);
}
.menu-toggle.open span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.menu-toggle.open span:nth-child(2) { opacity: 0; }
.menu-toggle.open span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ===== Hero 区域 ===== */
.hero {
  position: relative;
  min-height: 85vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding: 40px 20px 60px;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 40%, #c7d2fe 100%);
  z-index: -1;
}
.hero-bg::before {
  content: '';
  position: absolute;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(99,102,241,0.15) 0%, transparent 70%);
  top: -100px; right: -100px;
  border-radius: 50%;
}
.hero-content {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 60px;
  flex-wrap: wrap;
}
.hero-text { flex: 1 1 400px; }
.hero-text h2 {
  font-size: 2.8rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-text p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 30px;
  max-width: 520px;
}
.hero-buttons { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 30px; }
.hero-stats {
  display: flex;
  gap: 24px;
  font-size: 0.95rem;
  color: var(--text-secondary);
  flex-wrap: wrap;
}
.hero-stats span { background: rgba(99,102,241,0.08); padding: 6px 14px; border-radius: 40px; }

.hero-visual { flex: 1 1 300px; display: flex; justify-content: center; }
.phone-mockup {
  width: 220px;
  height: 440px;
  background: #1e293b;
  border-radius: 40px;
  padding: 12px;
  box-shadow: 0 30px 60px rgba(0,0,0,0.2);
  position: relative;
}
.phone-screen {
  width: 100%; height: 100%;
  background: #f1f5f9;
  border-radius: 30px;
  padding: 16px 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  overflow-y: auto;
}
.chat-bubble {
  max-width: 80%;
  padding: 10px 14px;
  border-radius: 20px;
  font-size: 0.85rem;
  line-height: 1.4;
  animation: fadeUp 0.5s ease;
}
.chat-bubble.me {
  background: var(--primary);
  color: white;
  align-self: flex-end;
  border-bottom-right-radius: 4px;
}
.chat-bubble.ai {
  background: white;
  color: var(--text);
  align-self: flex-start;
  border-bottom-left-radius: 4px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.04);
}
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===== 通用 Section ===== */
.section-header {
  text-align: center;
  margin-bottom: 40px;
  padding: 0 20px;
}
.section-header h2 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 10px;
}
.section-header p { color: var(--text-secondary); font-size: 1.05rem; }

/* ===== 下载区域 ===== */
.download-section {
  padding: 80px 20px;
  background: white;
}
.platform-grid {
  max-width: 900px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 24px;
}
.platform-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}
.platform-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  opacity: 0;
  transition: var(--transition);
}
.platform-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary-light);
}
.platform-card:hover::before { opacity: 1; }
.platform-icon { font-size: 3rem; margin-bottom: 12px; }
.platform-card h3 { font-size: 1.3rem; margin-bottom: 6px; }
.platform-card .version { color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 16px; }
.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--primary);
  color: white;
  padding: 12px 28px;
  border-radius: 40px;
  font-weight: 600;
  border: none;
  font-size: 1rem;
  transition: var(--transition);
}
.btn-download:hover { background: var(--primary-dark); transform: scale(1.02); box-shadow: 0 8px 20px rgba(99,102,241,0.3); }
.download-note {
  text-align: center;
  margin-top: 30px;
  color: var(--text-secondary);
  font-size: 0.9rem;
}
.download-note a { text-decoration: underline; }

/* ===== 功能卡片 ===== */
.features-section {
  padding: 80px 20px;
  background: var(--bg);
}
.features-grid {
  max-width: 1000px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 28px;
}
.feature-card {
  background: var(--card-bg);
  padding: 32px 24px;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: var(--transition);
  text-align: center;
  border: 1px solid transparent;
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary-light);
}
.feature-icon { font-size: 2.8rem; margin-bottom: 16px; }
.feature-card h3 { font-size: 1.3rem; margin-bottom: 10px; }
.feature-card p { color: var(--text-secondary); font-size: 0.95rem; }

/* ===== FAQ ===== */
.faq-section {
  padding: 80px 20px;
  background: white;
}
.faq-list {
  max-width: 700px;
  margin: 0 auto;
}
.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 8px 0;
}
.faq-question {
  width: 100%;
  background: none;
  border: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 0;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  text-align: left;
  transition: var(--transition);
}
.faq-question:hover { color: var(--primary); }
.faq-icon {
  font-size: 1.5rem;
  color: var(--primary);
  transition: var(--transition);
  flex-shrink: 0;
  margin-left: 12px;
}
.faq-item.active .faq-icon { transform: rotate(45deg); }
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease, padding 0.3s ease;
  padding: 0 0;
}
.faq-item.active .faq-answer {
  max-height: 300px;
  padding: 0 0 16px 0;
}
.faq-answer p { color: var(--text-secondary); line-height: 1.7; }

/* ===== Footer ===== */
.app-footer {
  background: #1e293b;
  color: #cbd5e1;
  padding: 30px 20px;
  text-align: center;
}
.footer-inner a { color: var(--primary-light); }
.footer-inner a:hover { text-decoration: underline; }
.footer-inner p + p { margin-top: 8px; }

/* ===== 返回顶部 ===== */
.back-to-top {
  position: fixed;
  bottom: 30px; right: 30px;
  width: 48px; height: 48px;
  border-radius: 50%;
  background: var(--primary);
  color: white;
  border: none;
  font-size: 1.4rem;
  box-shadow: 0 4px 16px rgba(99,102,241,0.3);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: var(--transition);
  z-index: 999;
}
.back-to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--primary-dark); transform: scale(1.05); }

/* ===== Toast ===== */
.toast {
  position: fixed;
  bottom: 80px; left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: #1e293b;
  color: white;
  padding: 12px 24px;
  border-radius: 40px;
  font-size: 0.95rem;
  box-shadow: 0 8px 30px rgba(0,0,0,0.2);
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  z-index: 2000;
  white-space: nowrap;
}
.toast.show { opacity: 1; visibility: visible; transform: translateX(-50%) translateY(0); }

/* ===== 按钮通用 ===== */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--primary);
  color: white;
  padding: 14px 32px;
  border-radius: 40px;
  font-weight: 600;
  border: none;
  font-size: 1rem;
  transition: var(--transition);
}
.btn-primary:hover { background: var(--primary-dark); transform: scale(1.02); box-shadow: 0 8px 20px rgba(99,102,241,0.3); }
.btn-outline {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
  padding: 12px 28px;
  border-radius: 40px;
  font-weight: 600;
  font-size: 1rem;
  transition: var(--transition);
}
.btn-outline:hover { background: var(--primary); color: white; }
.btn-block { width: 100%; justify-content: center; }
.btn-sm { padding: 8px 20px; font-size: 0.9rem; }

/* ===== 管理后台样式 ===== */
.admin-page {
  background: #0f172a;
  padding-top: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}
.admin-container {
  width: 100%;
  max-width: 960px;
  padding: 20px;
}
.login-screen {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 80vh;
}
.login-card {
  background: #1e293b;
  padding: 40px 32px;
  border-radius: var(--radius);
  width: 100%;
  max-width: 400px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.4);
}
.login-card h2 { color: white; text-align: center; margin-bottom: 28px; }
.input-group {
  margin-bottom: 20px;
}
.input-group label {
  display: block;
  color: #94a3b8;
  font-size: 0.9rem;
  margin-bottom: 6px;
}
.input-group input {
  width: 100%;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid #334155;
  background: #0f172a;
  color: white;
  font-size: 1rem;
  transition: var(--transition);
}
.input-group input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(99,102,241,0.2); }
.login-error { color: #f87171; font-size: 0.9rem; margin-top: 12px; text-align: center; }
.admin-panel { display: none; }
.admin-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 12px;
}
.admin-header h2 { color: white; }
.admin-user { color: #94a3b8; margin-right: 16px; }
.admin-actions { display: flex; align-items: center; gap: 12px; }
.admin-toolbar { margin-bottom: 20px; }
.table-wrapper { overflow-x: auto; }
table {
  width: 100%;
  border-collapse: collapse;
  background: #1e293b;
  border-radius: var(--radius-sm);
  overflow: hidden;
}
th, td {
  padding: 14px 16px;
  text-align: left;
  border-bottom: 1px solid #334155;
  color: #e2e8f0;
}
th { background: #0f172a; font-weight: 600; color: #94a3b8; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.5px; }
td { font-size: 0.95rem; }
td a { color: var(--primary-light); word-break: break-all; }
.table-tip { color: #64748b; margin-top: 12px; font-size: 0.9rem; }
.btn-edit, .btn-delete {
  background: none; border: none;
  padding: 6px 12px;
  border-radius: 8px;
  font-weight: 500;
  transition: var(--transition);
}
.btn-edit { color: #38bdf8; }
.btn-edit:hover { background: rgba(56,189,248,0.1); }
.btn-delete { color: #f87171; }
.btn-delete:hover { background: rgba(248,113,113,0.1); }

/* 模态框 */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 3000;
  padding: 20px;
}
.modal-card {
  background: #1e293b;
  padding: 36px 32px;
  border-radius: var(--radius);
  width: 100%;
  max-width: 480px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.5);
}
.modal-card h3 { color: white; margin-bottom: 24px; }
.modal-actions {
  display: flex;
  gap: 12px;
  margin-top: 24px;
  justify-content: flex-end;
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  body { padding-top: 60px; }
  .header-inner { height: 60px; }
  .nav-links {
    position: fixed;
    top: 60px; left: 0; right: 0;
    background: rgba(255,255,255,0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    gap: 0;
    padding: 16px 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    transform: translateY(-120%);
    transition: transform 0.4s ease;
    border-bottom: 1px solid var(--border);
    z-index: 999;
  }
  .nav-links.open { transform: translateY(0); }
  .nav-links a { padding: 14px 0; border-bottom: 1px solid var(--border); }
  .nav-links a:last-child { border-bottom: none; }
  .menu-toggle { display: flex; }
  .hero-content { flex-direction: column; gap: 40px; text-align: center; }
  .hero-text h2 { font-size: 2rem; }
  .hero-text p { margin-left: auto; margin-right: auto; }
  .hero-buttons { justify-content: center; }
  .hero-stats { justify-content: center; }
  .phone-mockup { width: 180px; height: 360px; }
  .platform-grid { grid-template-columns: 1fr 1fr; }
  .features-grid { grid-template-columns: 1fr; }
  .section-header h2 { font-size: 1.6rem; }
  .back-to-top { bottom: 20px; right: 20px; width: 44px; height: 44px; font-size: 1.2rem; }
  .admin-header { flex-direction: column; align-items: flex-start; }
  th, td { padding: 10px 8px; font-size: 0.85rem; }
  .modal-card { padding: 24px 20px; }
}

@media (max-width: 480px) {
  .platform-grid { grid-template-columns: 1fr; }
  .hero-text h2 { font-size: 1.7rem; }
  .btn-primary, .btn-outline { padding: 12px 24px; font-size: 0.95rem; }
}