:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --text-color: #111827;
    --muted-text: #4b5563;
    --background: #ffffff;
    --alt-background: #f9fafb;
    --border-color: #e5e7eb;
    --max-width: 1180px;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    color: var(--text-color);
    background-color: var(--background);
    line-height: 1.6;
}

a {
    color: var(--primary-color);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.container {
    width: min(92%, var(--max-width));
    margin: 0 auto;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.98);
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 0;
}

.logo {
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--text-color);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-links a {
    color: var(--text-color);
    font-weight: 500;
}

.nav-cta {
    font-weight: 600;
    color: var(--primary-color);
}

.nav-toggle {
    display: none;
    background: none;
    border: 1px solid var(--border-color);
    padding: 6px 10px;
    border-radius: 4px;
}

main {
    margin-top: 64px;
}

.hero {
    padding: 120px 0 60px;
    background-color: var(--alt-background);
}

.hero-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2.5rem;
}

.hero-text h1 {
    font-size: clamp(2rem, 3vw, 2.8rem);
    margin-bottom: 1rem;
}

.hero-text p {
    color: var(--muted-text);
    margin-bottom: 1.5rem;
}

.hero-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    color: var(--muted-text);
    font-size: 0.95rem;
}

.download-btn-primary {
    display: inline-block;
    background-color: var(--primary-color);
    color: #ffffff;
    padding: 16px 48px;
    font-size: 18px;
    font-weight: 600;
    border-radius: 6px;
    text-align: center;
}

.download-btn-primary:hover {
    background-color: var(--primary-dark);
}

.section {
    padding: 80px 0;
    border-bottom: 1px solid var(--border-color);
}

.section-title {
    font-size: 1.9rem;
    margin-bottom: 1rem;
}

.section-intro {
    color: var(--muted-text);
    margin-bottom: 2rem;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
}

.feature-card {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    background-color: #fff;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.info-card {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    background-color: #fff;
}

.list {
    list-style: disc;
    margin-left: 1.5rem;
    color: var(--muted-text);
}

.steps {
    counter-reset: step;
}

.steps li {
    list-style: none;
    margin-bottom: 0.8rem;
    padding-left: 2.5rem;
    position: relative;
}

.steps li::before {
    counter-increment: step;
    content: counter(step);
    position: absolute;
    left: 0;
    top: 0;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background-color: var(--primary-color);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
}

.quick-links {
    margin-top: 1rem;
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.error-page {
    padding: 140px 0 80px;
    text-align: center;
}

.footer {
    background-color: #fff;
    padding: 30px 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
    margin-top: 60px;
}

@media (max-width: 768px) {
    .nav-container {
        flex-wrap: wrap;
        gap: 1rem;
    }

    .nav-toggle {
        display: block;
    }

    .nav-links {
        width: 100%;
        flex-direction: column;
        display: none;
        border-top: 1px solid var(--border-color);
        padding-top: 1rem;
    }

    .site-nav.is-open .nav-links {
        display: flex;
    }

    .download-btn-primary {
        display: block;
        width: 100%;
    }

    .hero {
        padding-top: 100px;
    }
}