/* ============================================================
   RESET & BASE
   ============================================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: #f8fafc;
    color: #0f172a;
    line-height: 1.6;
}

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

a {
    text-decoration: none;
    color: inherit;
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
    display: inline-block;
    padding: 12px 32px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 2px solid transparent;
    text-align: center;
}

.btn-primary {
    background: #1e293b;
    color: #ffffff;
    border-color: #1e293b;
}

.btn-primary:hover {
    background: #0f172a;
    border-color: #0f172a;
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(30, 41, 59, 0.2);
}

.btn-outline {
    background: transparent;
    color: #1e293b;
    border-color: #1e293b;
}

.btn-outline:hover {
    background: #1e293b;
    color: #ffffff;
}

.btn-sm {
    padding: 8px 20px;
    font-size: 14px;
}

.btn-download {
    padding: 16px 48px;
    font-size: 18px;
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.navbar {
    background: #ffffff;
    border-bottom: 1px solid #e2e8f0;
    padding: 16px 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(8px);
    background: rgba(255, 255, 255, 0.9);
}

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

.logo {
    font-size: 24px;
    font-weight: 700;
    color: #0f172a;
}

.logo span {
    color: #3b82f6;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 32px;
}

.nav-links a {
    font-size: 15px;
    font-weight: 500;
    color: #475569;
    transition: color 0.2s;
    padding: 4px 0;
}

.nav-links a:hover,
.nav-links a.active {
    color: #0f172a;
    border-bottom: 2px solid #3b82f6;
}

/* ============================================================
   语言切换器
   ============================================================ */
.lang-switcher {
    margin-left: 20px;
}

.lang-switcher select {
    padding: 4px 8px;
    border: 1px solid #e2e8f0;
    border-radius: 6px;
    background: #ffffff;
    font-size: 13px;
    color: #475569;
    cursor: pointer;
    outline: none;
}

.lang-switcher select:hover {
    border-color: #3b82f6;
}

.lang-switcher select:focus {
    border-color: #3b82f6;
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
}

/* ============================================================
   HERO
   ============================================================ */
.hero {
    padding: 80px 0 60px;
    background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 100%);
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: start;
}

.hero-title {
    font-size: 48px;
    font-weight: 800;
    color: #0f172a;
    margin-bottom: 16px;
}

.hero-title span {
    color: #3b82f6;
}

.hero-subtitle {
    font-size: 22px;
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 12px;
}

.hero-desc {
    font-size: 17px;
    color: #475569;
    margin-bottom: 32px;
    max-width: 480px;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.hero-features {
    display: grid;
    gap: 24px;
}

.feature-card {
    background: #ffffff;
    padding: 24px 28px;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
    border: 1px solid #e2e8f0;
    transition: transform 0.2s, box-shadow 0.2s;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

.feature-icon {
    font-size: 28px;
    margin-bottom: 8px;
}

.feature-card h3 {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 4px;
    color: #0f172a;
}

.feature-card p {
    font-size: 14px;
    color: #64748b;
}

/* ============================================================
   DOWNLOAD PAGE
   ============================================================ */
.download-hero {
    padding: 60px 0 32px;
    text-align: center;
    background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 100%);
}

.download-hero h1 {
    font-size: 40px;
    font-weight: 800;
    margin-bottom: 8px;
}

.download-hero .subtitle {
    font-size: 18px;
    color: #475569;
}

.download-main {
    padding: 32px 0 48px;
}

.download-card {
    background: #ffffff;
    border-radius: 16px;
    border: 1px solid #e2e8f0;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
    padding: 48px 40px;
    text-align: center;
    max-width: 720px;
    margin: 0 auto;
}

.download-card-content .os-icon {
    font-size: 48px;
    margin-bottom: 12px;
}

.download-card-content h2 {
    font-size: 24px;
    font-weight: 500;
    color: #0f172a;
    margin-bottom: 8px;
}

.download-card-content h2 strong {
    font-weight: 700;
}

.system-requirement {
    font-size: 15px;
    color: #475569;
    margin-bottom: 24px;
}

.versions-hint {
    margin-top: 16px;
    font-size: 14px;
    color: #94a3b8;
}

/* ============================================================
   ALL VERSIONS
   ============================================================ */
.all-versions {
    padding: 40px 0 80px;
}

.section-title {
    font-size: 28px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 32px;
}

.version-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 32px;
    max-width: 820px;
    margin: 0 auto;
}

.version-card {
    background: #ffffff;
    padding: 32px 24px;
    border-radius: 12px;
    border: 1px solid #e2e8f0;
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
}

.version-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

.version-card .version-icon {
    font-size: 36px;
    margin-bottom: 8px;
}

.version-card h3 {
    font-size: 18px;
    font-weight: 700;
}

.version-number {
    font-size: 14px;
    color: #94a3b8;
    margin-bottom: 12px;
}

.tag {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 12px;
}

.tag-warning {
    background: #fef3c7;
    color: #92400e;
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
    background: #ffffff;
    border-top: 1px solid #e2e8f0;
    padding: 24px 0;
    text-align: center;
    font-size: 14px;
    color: #94a3b8;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 992px) {
    .hero-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    .hero-title {
        font-size: 36px;
    }
    .hero-desc {
        max-width: 100%;
    }
}

@media (max-width: 640px) {
    .nav-container {
        flex-direction: column;
        gap: 12px;
    }
    .nav-links {
        gap: 16px;
        flex-wrap: wrap;
        justify-content: center;
    }
    .lang-switcher {
        margin-left: 0;
        margin-top: 8px;
    }
    .hero {
        padding: 48px 0 40px;
    }
    .hero-title {
        font-size: 28px;
    }
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    .hero-buttons .btn {
        width: 100%;
        text-align: center;
        justify-content: center;
    }
    .download-card {
        padding: 32px 20px;
    }
    .download-card-content h2 {
        font-size: 20px;
    }
    .version-grid {
        grid-template-columns: 1fr;
    }
    .download-hero h1 {
        font-size: 28px;
    }
}