/* ========== CSS Variables ========== */
:root {
  --bg-primary: #eef4fb;
  --bg-secondary: #e0ebf7;
  --bg-card: #ffffff;
  --bg-card-hover: #f5f8fc;
  --text-primary: #1a1a2e;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --accent: #06b6d4;
  --accent-light: #0891b2;
  --accent-dark: #0e7490;
  --accent-glow: rgba(6, 182, 212, 0.2);
  --border: #d4e0ee;
  --border-light: #bccde0;
  --gradient-1: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
  --gradient-2: linear-gradient(135deg, #0891b2 0%, #6366f1 100%);
  --gradient-dark: linear-gradient(180deg, #eef4fb 0%, #e0ebf7 50%, #ffffff 100%);
  --radius: 12px;
  --radius-sm: 8px;
  --radius-lg: 20px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.1);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========== Reset & Base ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
ul { list-style: none; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

/* ========== Navbar ========== */
.navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0,0,0,0.06);
  transition: var(--transition);
}
.navbar .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 72px;
}
.logo {
  display: flex; align-items: center; gap: 10px;
  font-size: 1.25rem; font-weight: 700; letter-spacing: 0.5px;
  color: #1a1a2e;
}
.logo img {
  background: rgba(0,0,0,0.04);
  border-radius: 8px; padding: 4px 8px;
}
.logo-icon {
  width: 40px; height: 40px;
  background: var(--gradient-1); border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.2rem; color: #fff;
}
.nav-links { display: flex; gap: 36px; align-items: center; }
.nav-links a {
  font-size: 0.95rem; color: #4a4a6a;
  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(--gradient-1); transition: var(--transition); border-radius: 2px;
}
.nav-links a:hover, .nav-links a.active { color: #1a1a2e; }
.nav-links a:hover::after, .nav-links a.active::after { width: 100%; }
.nav-cta {
  padding: 10px 24px; background: var(--gradient-1);
  border-radius: 50px; color: #fff !important; font-weight: 600;
  font-size: 0.9rem; transition: var(--transition);
}
.nav-cta:hover { box-shadow: 0 0 24px var(--accent-glow); transform: translateY(-1px); }
.nav-cta::after { display: none !important; }

.hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; background: none; border: none; padding: 4px; }
.hamburger span { width: 26px; height: 2px; background: #1a1a2e; border-radius: 2px; transition: var(--transition); }

/* ========== Page Hero (inner pages) ========== */
.page-hero {
  padding: 160px 0 80px;
  text-align: center;
  background: var(--gradient-dark);
  position: relative;
  overflow: hidden;
}
.page-hero::before {
  content: ''; position: absolute; top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: radial-gradient(circle at 50% 0%, var(--accent-glow) 0%, transparent 50%);
  pointer-events: none;
}
.page-hero h1 {
  font-size: 3rem; font-weight: 800; letter-spacing: -0.5px;
  background: var(--gradient-1); -webkit-background-clip: text;
  -webkit-text-fill-color: transparent; background-clip: text;
  position: relative;
}
.page-hero p { font-size: 1.15rem; color: var(--text-secondary); max-width: 600px; margin: 16px auto 0; position: relative; }

/* ========== Buttons ========== */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 32px; border-radius: 50px; font-size: 1rem;
  font-weight: 600; cursor: pointer; border: none;
  transition: var(--transition); white-space: nowrap;
}
.btn-primary { background: var(--gradient-1); color: #fff; box-shadow: 0 4px 16px var(--accent-glow); }
.btn-primary:hover { box-shadow: 0 6px 28px var(--accent-glow); transform: translateY(-2px); }
.btn-outline { background: transparent; color: var(--text-primary); border: 1px solid var(--border-light); }
.btn-outline:hover { border-color: var(--accent); background: rgba(6, 182, 212, 0.05); }
.btn-lg { padding: 18px 40px; font-size: 1.1rem; }

/* ========== Section ========== */
.section { padding: 100px 0; }
.section-header { text-align: center; margin-bottom: 60px; }
.section-tag {
  display: inline-block; padding: 6px 16px;
  background: rgba(6, 182, 212, 0.1); color: var(--accent-light);
  border-radius: 50px; font-size: 0.85rem; font-weight: 600;
  margin-bottom: 16px; letter-spacing: 1px; text-transform: uppercase;
}
.section-header h2 { font-size: 2.5rem; font-weight: 800; letter-spacing: -0.5px; margin-bottom: 12px; }
.section-header p { color: var(--text-secondary); font-size: 1.1rem; max-width: 600px; margin: 0 auto; }

/* ========== Nav User Auth ========== */
.nav-auth { display: flex; align-items: center; gap: 10px; }
.nav-login-btn {
  padding: 8px 20px; border: 1px solid rgba(0,0,0,0.12);
  border-radius: 50px; background: transparent; color: #4a4a6a;
  font-size: 0.88rem; cursor: pointer; transition: var(--transition); font-family: inherit;
  display: flex; align-items: center; gap: 6px;
}
.nav-login-btn:hover { border-color: var(--accent); color: var(--accent-dark); }
.nav-user-menu { position: relative; display: flex; align-items: center; gap: 8px; cursor: pointer; }
.nav-user-avatar {
  width: 34px; height: 34px; border-radius: 50%;
  background: var(--gradient-1); display: flex; align-items: center; justify-content: center;
  font-size: 0.85rem; color: #fff; font-weight: 700;
}
.nav-user-email { font-size: 0.85rem; color: #4a4a6a; max-width: 140px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nav-user-dropdown {
  position: absolute; top: 100%; right: 0; margin-top: 8px;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 8px; min-width: 160px;
  box-shadow: var(--shadow-lg); display: none; z-index: 100;
}
.nav-user-dropdown.show { display: block; }
.nav-user-dropdown a, .nav-user-dropdown button {
  display: block; width: 100%; padding: 10px 14px; text-align: left;
  border: none; background: transparent; color: var(--text-secondary);
  font-size: 0.88rem; cursor: pointer; border-radius: var(--radius-sm);
  transition: var(--transition); font-family: inherit;
}
.nav-user-dropdown a:hover, .nav-user-dropdown button:hover { background: rgba(6,182,212,0.06); color: var(--text-primary); }
.nav-user-dropdown button.logout-btn:hover { background: rgba(239,68,68,0.06); color: #ef4444; }

/* ========== Auth Modal ========== */
.auth-overlay {
  position: fixed; inset: 0; background: rgba(0,0,0,0.7); z-index: 9999;
  display: flex; align-items: center; justify-content: center;
  backdrop-filter: blur(4px);
}
.auth-modal {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-lg); padding: 36px 32px;
  width: 90%; max-width: 420px; position: relative;
}
.auth-modal .am-close {
  position: absolute; top: 14px; right: 18px;
  background: none; border: none; color: var(--text-muted);
  font-size: 1.4rem; cursor: pointer; padding: 4px; line-height: 1;
}
.auth-modal .am-tabs { display: flex; gap: 0; margin-bottom: 28px; border-bottom: 1px solid var(--border); }
.auth-modal .am-tab {
  flex: 1; padding: 12px; text-align: center; background: none;
  border: none; color: var(--text-secondary); font-size: 0.95rem;
  font-weight: 600; cursor: pointer; border-bottom: 2px solid transparent;
  transition: var(--transition); font-family: inherit;
}
.auth-modal .am-tab.active { color: var(--accent-light); border-bottom-color: var(--accent); }
.auth-modal .form-group { margin-bottom: 16px; }
.auth-modal label { display: block; font-size: 0.85rem; font-weight: 600; color: var(--text-primary); margin-bottom: 6px; }
.auth-modal input {
  width: 100%; padding: 11px 14px; background: var(--bg-secondary);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  color: var(--text-primary); font-size: 0.92rem; font-family: inherit;
  outline: none; transition: var(--transition);
}
.auth-modal input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(6,182,212,0.1); }
.auth-modal .btn { width: 100%; justify-content: center; margin-top: 4px; }
.auth-modal .am-msg {
  text-align: center; padding: 8px; border-radius: var(--radius-sm);
  font-size: 0.82rem; margin-top: 12px; display: none;
}
.auth-modal .am-msg.error { display: block; background: rgba(239,68,68,0.1); color: #ef4444; }
.auth-modal .am-msg.success { display: block; background: rgba(16,185,129,0.1); color: #10b981; }

/* ========== Footer ========== */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: 60px 0 30px;
}
.footer-grid {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px; margin-bottom: 40px;
}
.footer-brand p { color: var(--text-secondary); margin-top: 12px; font-size: 0.9rem; max-width: 300px; }
.footer-col h4 { font-size: 1rem; margin-bottom: 16px; color: var(--text-primary); }
.footer-col a { display: block; color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 10px; transition: var(--transition); }
.footer-col a:hover { color: var(--accent-light); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 24px; text-align: center;
  color: var(--text-muted); font-size: 0.85rem;
}

/* ========== Responsive Nav ========== */
@media (max-width: 968px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
  .nav-links.mobile-open {
    display: flex; flex-direction: column;
    position: absolute; top: 72px; left: 0; right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    padding: 24px; gap: 16px;
    border-bottom: 1px solid rgba(0,0,0,0.06);
  }
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
  .page-hero h1 { font-size: 2rem; }
  .section-header h2 { font-size: 1.8rem; }
  .section { padding: 60px 0; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .page-hero h1 { font-size: 1.6rem; }
  .section-header h2 { font-size: 1.5rem; }
  .footer-grid { grid-template-columns: 1fr; }
}