/* ============ 全局 ============ */
* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif; color: #333; line-height: 1.6; }

/* ============ 导航栏 ============ */
.navbar { background: #fff; border-bottom: 1px solid #eee; position: sticky; top: 0; z-index: 100; }
.nav-container { max-width: 1200px; margin: 0 auto; padding: 0 24px; display: flex; align-items: center; height: 64px; }
.nav-logo { display: flex; align-items: center; gap: 10px; text-decoration: none; color: #333; font-weight: 700; font-size: 20px; }
.logo-img { width: 36px; height: 36px; border-radius: 50%; object-fit: cover; }
.nav-links { margin-left: auto; display: flex; align-items: center; gap: 24px; }
.nav-links a { text-decoration: none; color: #555; font-size: 14px; transition: color 0.2s; }
.nav-links a:hover { color: #667eea; }

.btn-primary { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; padding: 10px 20px; border-radius: 8px; text-decoration: none; font-size: 14px; font-weight: 600; border: none; cursor: pointer; transition: opacity 0.2s, transform 0.2s; display: inline-block; }
.btn-primary:hover { opacity: 0.9; transform: translateY(-1px); }
.btn-lg { padding: 14px 32px; font-size: 16px; border-radius: 10px; }
.btn-outline { border: 2px solid #667eea; color: #667eea; padding: 12px 30px; border-radius: 10px; text-decoration: none; font-size: 16px; font-weight: 600; transition: all 0.2s; display: inline-block; }
.btn-outline:hover { background: #667eea; color: #fff; }

/* ============ Hero ============ */
.hero { max-width: 1200px; margin: 0 auto; padding: 80px 24px; display: flex; align-items: center; gap: 60px; }
.hero-content { flex: 1; }
.hero-content h1 { font-size: 48px; font-weight: 800; line-height: 1.2; margin-bottom: 20px; background: linear-gradient(135deg, #667eea, #764ba2); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero-content p { font-size: 18px; color: #666; margin-bottom: 32px; line-height: 1.8; }
.hero-btns { display: flex; gap: 16px; }
.hero-visual { flex: 0 0 380px; }

/* 聊天预览 */
.chat-preview { background: #fff; border-radius: 16px; box-shadow: 0 20px 60px rgba(0,0,0,0.15); overflow: hidden; width: 100%; }
.cp-header { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; padding: 14px 18px; font-weight: 600; font-size: 14px; }
.cp-msg { padding: 10px 14px; margin: 8px; border-radius: 12px; font-size: 13px; max-width: 80%; }
.cp-msg.bot { background: #f0f0f5; color: #333; border-bottom-left-radius: 4px; }
.cp-msg.user { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; margin-left: auto; border-bottom-right-radius: 4px; }
.cp-input { margin: 12px; padding: 10px 14px; background: #f5f5f5; border-radius: 20px; font-size: 13px; color: #999; }

/* ============ Features ============ */
.features { background: #f8f9fc; padding: 80px 24px; text-align: center; }
.features h2 { font-size: 36px; margin-bottom: 48px; }
.feature-grid { max-width: 1100px; margin: 0 auto; display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feature-card { background: #fff; padding: 32px 24px; border-radius: 16px; text-align: left; transition: transform 0.2s, box-shadow 0.2s; }
.feature-card:hover { transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.1); }
.feature-icon { font-size: 36px; margin-bottom: 16px; }
.feature-card h3 { font-size: 18px; margin-bottom: 8px; }
.feature-card p { font-size: 14px; color: #666; line-height: 1.7; }

/* ============ 定价 ============ */
.pricing-preview, .pricing-page { padding: 80px 24px; text-align: center; }
.pricing-preview h2, .pricing-page h1 { font-size: 36px; margin-bottom: 16px; }
.pricing-subtitle { color: #666; margin-bottom: 48px; }
.plan-grid { max-width: 1100px; margin: 0 auto; display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.plan-card { background: #fff; border: 2px solid #eee; border-radius: 16px; padding: 32px 24px; text-align: center; position: relative; transition: transform 0.2s; }
.plan-card:hover { transform: translateY(-4px); }
.plan-popular { border-color: #667eea; box-shadow: 0 8px 30px rgba(102,126,234,0.2); }
.plan-badge { position: absolute; top: -12px; left: 50%; transform: translateX(-50%); background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; padding: 4px 16px; border-radius: 20px; font-size: 12px; font-weight: 600; }
.plan-card h3 { font-size: 20px; margin-bottom: 16px; }
.plan-price { margin-bottom: 8px; }
.price-symbol { font-size: 24px; font-weight: 600; }
.price-num { font-size: 48px; font-weight: 800; }
.price-unit { font-size: 16px; color: #999; }
.plan-tokens { color: #667eea; font-weight: 600; margin-bottom: 20px; font-size: 14px; }
.plan-features { list-style: none; text-align: left; margin-bottom: 24px; }
.plan-features li { padding: 8px 0; font-size: 14px; color: #555; }
.plan-btn { width: 100%; text-align: center; }

/* ============ 使用流程 ============ */
.how-it-works { padding: 80px 24px; text-align: center; background: #fff; }
.how-it-works h2 { font-size: 36px; margin-bottom: 48px; }
.steps { display: flex; align-items: center; justify-content: center; gap: 16px; max-width: 800px; margin: 0 auto; }
.step { flex: 1; }
.step-num { width: 56px; height: 56px; border-radius: 50%; background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; font-size: 24px; font-weight: 700; display: flex; align-items: center; justify-content: center; margin: 0 auto 16px; }
.step h3 { font-size: 18px; margin-bottom: 8px; }
.step p { font-size: 14px; color: #666; }
.step-arrow { font-size: 32px; color: #ccc; }

/* ============ 认证页面 ============ */
.auth-page { min-height: calc(100vh - 64px); display: flex; align-items: center; justify-content: center; padding: 40px 24px; background: #f8f9fc; }
.auth-card { background: #fff; padding: 40px; border-radius: 16px; box-shadow: 0 4px 20px rgba(0,0,0,0.08); width: 100%; max-width: 420px; }
.auth-card h1 { font-size: 28px; margin-bottom: 8px; }
.auth-sub { color: #666; font-size: 14px; margin-bottom: 24px; }
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 6px; color: #555; }
.form-group input { width: 100%; padding: 12px 14px; border: 1px solid #e0e0e0; border-radius: 8px; font-size: 14px; outline: none; transition: border-color 0.2s; }
.form-group input:focus { border-color: #667eea; }
.auth-btn { width: 100%; padding: 14px; font-size: 16px; margin-top: 8px; }
.auth-footer { text-align: center; margin-top: 16px; font-size: 14px; color: #666; }
.auth-footer a { color: #667eea; text-decoration: none; font-weight: 600; }

.msg-box { padding: 12px 16px; border-radius: 8px; font-size: 14px; margin-top: 16px; text-align: center; }
.msg-success { background: #e8f5e9; color: #2e7d32; }
.msg-error { background: #fce4ec; color: #c62828; }
.msg-loading { background: #e3f2fd; color: #1565c0; }
.msg-box code { background: #f5f5f5; padding: 2px 6px; border-radius: 4px; font-size: 12px; word-break: break-all; }

/* ============ 页脚 ============ */
.footer { background: #1a1a2e; color: #ccc; padding: 48px 24px 24px; }
.footer-content { max-width: 1100px; margin: 0 auto; display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 40px; }
.footer-col h4 { color: #fff; margin-bottom: 16px; font-size: 16px; }
.footer-col p, .footer-col a { display: block; font-size: 14px; color: #999; text-decoration: none; margin-bottom: 8px; }
.footer-col a:hover { color: #fff; }
.footer-bottom { max-width: 1100px; margin: 32px auto 0; padding-top: 16px; border-top: 1px solid #333; text-align: center; font-size: 13px; }

/* ============ 响应式 ============ */
@media (max-width: 768px) {
    .hero { flex-direction: column; padding: 40px 20px; gap: 40px; }
    .hero-content h1 { font-size: 32px; }
    .hero-visual { flex: 0 0 auto; width: 100%; }
    .feature-grid { grid-template-columns: 1fr; }
    .plan-grid { grid-template-columns: 1fr; max-width: 400px; }
    .steps { flex-direction: column; }
    .step-arrow { transform: rotate(90deg); }
    .footer-content { grid-template-columns: 1fr; }
    .hero-btns { flex-direction: column; }
}