/* ===== CSS Variables & Reset ===== */
:root {
    --primary: #2563EB;
    --primary-dark: #1D4ED8;
    --primary-light: #3B82F6;
    --secondary: #0EA5E9;
    --bg: #F8FBFF;
    --bg-card: #FFFFFF;
    --text: #1E293B;
    --text-secondary: #64748B;
    --text-muted: #94A3B8;
    --border: #E2E8F0;
    --border-light: #F1F5F9;
    --shadow: 0 4px 16px rgba(37,99,235,0.09);
    --shadow-lg: 0 12px 40px rgba(37,99,235,0.14);
    --radius: 12px;
    --radius-lg: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
    min-height: 100vh;
}

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

.page {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 48px 24px 32px;
    background:
        radial-gradient(ellipse 80% 50% at 50% 0%, rgba(37,99,235,0.1) 0%, transparent 60%),
        radial-gradient(ellipse 60% 40% at 80% 5%, rgba(14,165,233,0.07) 0%, transparent 50%);
}

/* ===== Header / Logo ===== */
.header {
    margin-bottom: 48px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo-icon { display: flex; }

.logo-text {
    font-size: 20px;
    font-weight: 700;
    color: var(--text);
    letter-spacing: -0.3px;
}

/* ===== Hero ===== */
.hero {
    text-align: center;
    margin-bottom: 48px;
    max-width: 560px;
}

.badge {
    display: inline-flex;
    padding: 5px 14px;
    background: linear-gradient(135deg, rgba(37,99,235,0.1), rgba(14,165,233,0.1));
    border: 1px solid rgba(37,99,235,0.18);
    border-radius: 100px;
    font-size: 13px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 20px;
}

.hero h1 {
    font-size: 44px;
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: -1px;
    background: linear-gradient(135deg, var(--text) 0%, var(--primary-dark) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 14px;
}

.hero-subtitle {
    font-size: 18px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 10px;
}

.hero-desc {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ===== Download Section ===== */
.download {
    width: 100%;
    max-width: 960px;
}

.platform-tabs {
    display: flex;
    gap: 6px;
    margin-bottom: 36px;
    background: white;
    padding: 5px;
    border-radius: 14px;
    border: 1px solid var(--border);
    max-width: 320px;
    margin-left: auto;
    margin-right: auto;
    box-shadow: 0 2px 8px rgba(0,0,0,0.04);
}

.platform-tab {
    display: flex;
    align-items: center;
    gap: 7px;
    padding: 10px 24px;
    border: none;
    background: transparent;
    border-radius: 10px;
    font-size: 14px;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    flex: 1;
    justify-content: center;
}

.platform-tab:hover { color: var(--text); }

.platform-tab.active {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(37,99,235,0.28);
}

.platform-tab svg { width: 17px; height: 17px; }

/* Panels */
.download-panel {
    display: none;
    animation: fadeIn 0.3s ease;
}

.download-panel.active { display: block; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Single Card */
.download-cards-win {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    max-width: 760px;
    margin: 0 auto;
}

.download-card-single {
    background: white;
    border: 1.5px solid var(--primary-light);
    border-radius: var(--radius-lg);
    padding: 36px 40px;
    max-width: 440px;
    margin: 0 auto;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.download-card-single:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    display: flex;
    align-items: flex-start;
    gap: 16px;
}

.os-icon {
    width: 52px;
    height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 14px;
    flex-shrink: 0;
}

.win-icon {
    background: linear-gradient(135deg, #0078D4, #00BCF2);
    color: white;
}

.mac-icon-big {
    background: linear-gradient(135deg, #333, #555);
    color: white;
}

.card-header h3 {
    font-size: 18px;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 4px;
}

.version {
    font-size: 13px;
    color: var(--text-muted);
    font-weight: 500;
}

.card-desc {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 11px 20px;
    border-radius: 10px;
    font-size: 14px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    width: 100%;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    box-shadow: 0 4px 14px rgba(99,102,241,0.28);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(99,102,241,0.38);
}

.btn-secondary {
    background: white;
    color: var(--text);
    border: 1.5px solid var(--border);
}

.btn-secondary:hover {
    border-color: var(--primary-light);
    color: var(--primary);
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.btn svg { flex-shrink: 0; }

/* ===== Footer ===== */
.footer {
    margin-top: auto;
    padding-top: 60px;
    text-align: center;
}

.footer p {
    font-size: 13px;
    color: var(--text-muted);
}

/* ===== Responsive ===== */
@media (max-width: 480px) {
    .page { padding: 32px 16px 24px; }
    .hero h1 { font-size: 28px; }
    .logo-text { font-size: 17px; }
    .download-cards-win {
        grid-template-columns: 1fr;
        max-width: 440px;
    }
    .download-card-single { padding: 28px 24px; }
}