* {
    box-sizing: border-box;
}

body {
    font-family: "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
    margin: 0;
    color: #1f2937;
    min-height: 100vh;
    background:
        radial-gradient(circle at top left, rgba(102,126,234,0.18), transparent 30%),
        radial-gradient(circle at top right, rgba(118,75,162,0.15), transparent 28%),
        linear-gradient(180deg, #f7f9ff 0%, #ffffff 50%, #f6f7fb 100%);
}

a {
    text-decoration: none;
}

.navbar {
    width: 100%;
    min-height: 74px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 20px;
    background: rgba(255,255,255,0.78);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #eef2f7;
    position: sticky;
    top: 0;
    z-index: 50;
}

.nav-inner {
    width: 100%;
    max-width: 1180px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    color: #111827;
    font-size: 22px;
    font-weight: 800;
    flex-shrink: 0;
}

.brand-icon {
    width: 44px;
    height: 44px;
    border-radius: 16px;
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 12px 28px rgba(102,126,234,0.26);
    font-size: 18px;
    flex-shrink: 0;
}

.nav-links {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.nav-link {
    color: #4b5563;
    font-size: 14px;
    padding: 10px 14px;
    border-radius: 999px;
    transition: all .2s ease;
}

.nav-link:hover {
    background: rgba(102,126,234,0.10);
    color: #4f46e5;
}

.nav-link.active {
    background: #111827;
    color: #fff;
}

.page-wrap {
    max-width: 1180px;
    margin: 0 auto;
    padding: 34px 20px 44px;
}

.hero {
    text-align: center;
    margin-bottom: 28px;
}

.hero h1 {
    margin: 0 0 12px;
    font-size: 48px;
    font-weight: 900;
    color: #111827;
    letter-spacing: -1px;
}

.hero p {
    margin: 0 auto;
    color: #667085;
    font-size: 16px;
    line-height: 1.9;
    max-width: 860px;
}

.tip {
    background: #eef6ff;
    border: 1px solid #cfe3ff;
    color: #1d4ed8;
    border-radius: 18px;
    padding: 16px 18px;
    font-size: 14px;
    line-height: 1.8;
    margin-bottom: 20px;
}

.card {
    background: rgba(255,255,255,0.92);
    border: 1px solid rgba(226,232,240,0.95);
    border-radius: 28px;
    box-shadow: 0 20px 50px rgba(15,23,42,0.08);
    overflow: hidden;
}

.card-head {
    padding: 22px 24px;
    border-bottom: 1px solid #eef2f7;
    background: linear-gradient(180deg, rgba(102,126,234,0.05), rgba(255,255,255,0));
}

.card-title {
    font-size: 20px;
    font-weight: 800;
    color: #111827;
    margin-bottom: 6px;
}

.card-desc {
    font-size: 14px;
    color: #6b7280;
    line-height: 1.8;
}

.card-body {
    padding: 24px;
}

.footer {
    text-align: center;
    color: #8a94a6;
    font-size: 14px;
    padding: 28px 20px 40px;
}

@media (max-width: 860px) {
    .nav-links {
        display: none;
    }

    .hero h1 {
        font-size: 34px;
    }

    .page-wrap {
        padding-top: 24px;
    }
}