body {
    text-align: center;
    padding: 60px 20px;
    font-size: 18px;
    background: var(--bg, #f8fafc);
    font-family: system-ui, -apple-system, sans-serif;
    transition: background 0.3s ease;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

/* ── 导航栏 ── */
.nav-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 5vw;
    height: 56px;
    background: var(--bg-card, #ffffff);
    border-bottom: 1px solid var(--border, #e2e8f0);
    z-index: 99;
    transition: background 0.3s ease, border-color 0.3s ease;
}

.logo {
    font-size: 20px;
    font-weight: 800;
    color: var(--primary, #6366f1);
    text-decoration: none;
}

.nav-controls {
    display: flex;
    gap: 8px;
    align-items: center;
}

.theme-toggle {
    background: none;
    border: 1.5px solid var(--border, #e2e8f0);
    border-radius: 50px;
    padding: 5px 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 12px;
    color: var(--text-muted, #64748b);
    transition: all 0.2s ease;
}

.theme-toggle:hover {
    border-color: var(--primary, #6366f1);
    color: var(--primary, #6366f1);
}

.theme-toggle .icon {
    font-size: 13px;
}

.lang-select {
    background: var(--bg-card, #ffffff);
    border: 1.5px solid var(--border, #e2e8f0);
    border-radius: 8px;
    padding: 4px 10px;
    font-size: 12px;
    color: var(--text, #1e293b);
    cursor: pointer;
    transition: all 0.2s ease;
}

.lang-select:hover {
    border-color: var(--primary, #6366f1);
}

.lang-select option {
    background: var(--bg-card, #ffffff);
    color: var(--text, #1e293b);
}

/* ── 下载卡片 ── */
.box {
    max-width: 480px;
    margin: 0 auto;
    background: var(--bg-card, #ffffff);
    padding: 40px 32px;
    border-radius: 20px;
    box-shadow: var(--shadow, 0 4px 24px rgba(0,0,0,0.08));
    border: 1px solid var(--border, #e2e8f0);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.box::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary, #6366f1), var(--accent, #8b5cf6));
}

.version-tag {
    display: inline-block;
    background: rgba(99,102,241,0.1);
    color: var(--primary, #6366f1);
    font-size: 11px;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 99px;
    margin-bottom: 16px;
    letter-spacing: 0.5px;
    border: 1px solid rgba(99,102,241,0.2);
}

h2 {
    color: var(--text, #1e293b);
    margin-bottom: 8px;
    font-size: 22px;
    font-weight: 700;
    transition: color 0.3s ease;
}

.subtitle {
    color: var(--text-muted, #64748b);
    font-size: 14px;
    margin-bottom: 28px;
    transition: color 0.3s ease;
}

/* ── 下载按钮组 ── */
.btn-group {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-top: 20px;
}

.down-btn {
    padding: 14px 24px;
    background: var(--primary, #6366f1);
    color: #fff;
    border-radius: 12px;
    text-decoration: none;
    font-weight: 600;
    font-size: 14px;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    border: none;
    cursor: pointer;
}

.down-btn:hover {
    background: var(--primary-dark, #4f46e5);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(99,102,241,0.3);
}

.down-btn.secondary {
    background: var(--bg, #f8fafc);
    color: var(--text, #1e293b);
    border: 1.5px solid var(--border, #e2e8f0);
}

.down-btn.secondary:hover {
    background: var(--primary-light, #e0e7ff);
    border-color: var(--primary, #6366f1);
    color: var(--primary, #6366f1);
    transform: translateY(-1px);
    box-shadow: none;
}

.down-btn .icon {
    font-size: 16px;
}

/* ── 倒计时提示 ── */
.count-text {
    margin-top: 20px;
    font-size: 13px;
    color: var(--text-muted, #64748b);
    transition: color 0.3s ease;
}

.count-text .timer {
    color: var(--primary, #6366f1);
    font-weight: 700;
    font-size: 18px;
}

/* ── 说明文字 ── */
.tip {
    color: var(--text-muted, #64748b);
    margin-bottom: 24px;
    line-height: 1.7;
    font-size: 13px;
    padding: 12px 16px;
    background: rgba(99,102,241,0.06);
    border-radius: 10px;
    border-left: 3px solid var(--primary, #6366f1);
    text-align: left;
}

/* ── 版本信息 ── */
.version-info {
    margin-top: 24px;
    padding: 16px;
    background: var(--bg, #f8fafc);
    border-radius: 10px;
    border: 1px solid var(--border, #e2e8f0);
    font-size: 12px;
    color: var(--text-muted, #64748b);
    line-height: 1.8;
    transition: all 0.3s ease;
}

.version-info strong {
    color: var(--text, #1e293b);
}

/* ── 暗色主题覆盖 ── */
[data-theme="dark"] body {
    background: #0f172a;
}

[data-theme="dark"] .box {
    background: #1e293b;
    border-color: #334155;
    box-shadow: 0 4px 24px rgba(0,0,0,0.4);
}

[data-theme="dark"] .down-btn.secondary {
    background: #1e293b;
    color: #f1f5f9;
    border-color: #334155;
}

[data-theme="dark"] .down-btn.secondary:hover {
    background: #312e81;
    border-color: #818cf8;
    color: #c7d2fe;
}

[data-theme="dark"] .version-info {
    background: #1e293b;
    border-color: #334155;
    color: #94a3b8;
}

[data-theme="dark"] .tip {
    background: rgba(99,102,241,0.15);
    color: #cbd5e1;
}

/* ── Toast ── */
.toast {
    position: fixed;
    top: 24px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text, #1e293b);
    color: var(--bg, #f8fafc);
    padding: 10px 24px;
    border-radius: 50px;
    font-size: 13px;
    font-weight: 500;
    display: none;
    z-index: 9999;
    box-shadow: 0 4px 16px rgba(0,0,0,0.2);
}

/* ── 响应式 ── */
@media (max-width: 480px) {
    .box {
        padding: 32px 24px;
        margin: 0 12px;
    }
    h2 {
        font-size: 20px;
    }
    .nav-bar {
        padding: 0 4vw;
    }
}