/* ===== 基础变量 ===== */
:root {
    --color-primary: #212121;
    --color-bg: #F5F5F5;
    --color-divider: #E8E8E8;
    --color-text-secondary: #888;
    --color-text-muted: #999;
    --color-hover: #424242;
    --radius: 12px;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}

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

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

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

/* ===== 导航栏 ===== */
.navbar {
    background: #fff;
    border-bottom: 1px solid var(--color-divider);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-inner {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: 1px;
}

.nav-menu {
    display: flex;
    gap: 28px;
}

.nav-menu a {
    font-size: 15px;
    color: var(--color-text-secondary);
    transition: color 0.2s;
}

.nav-menu a:hover {
    color: var(--color-primary);
}

/* ===== Hero 区 ===== */
.hero {
    background: var(--color-primary);
    color: #fff;
    text-align: center;
    padding: 96px 24px 88px;
}

.hero h1 {
    font-size: 56px;
    font-weight: 800;
    letter-spacing: 4px;
    margin-bottom: 16px;
}

.hero-sub {
    font-size: 20px;
    color: #cfcfcf;
    margin-bottom: 40px;
}

.hero-cta {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ===== 按钮 ===== */
.btn {
    display: inline-block;
    padding: 12px 32px;
    border-radius: var(--radius);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: background 0.2s, color 0.2s;
}

.btn-primary {
    background: var(--color-primary);
    color: #fff;
}

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

.btn-outline {
    background: transparent;
    color: #fff;
    border: 1px solid #fff;
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.12);
}

/* ===== 区块标题 ===== */
.section-title {
    text-align: center;
    margin-bottom: 48px;
}

.section-title h2 {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 8px;
}

.section-title p {
    color: var(--color-text-secondary);
    font-size: 15px;
}

/* ===== 功能介绍 ===== */
.features {
    max-width: 1100px;
    margin: 0 auto;
    padding: 80px 24px;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.card {
    background: #fff;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 36px 28px;
    text-align: center;
}

.card-icon {
    font-size: 40px;
    margin-bottom: 16px;
}

.card h3 {
    font-size: 19px;
    margin-bottom: 12px;
}

.card p {
    color: var(--color-text-secondary);
    font-size: 14px;
}

/* ===== 下载区 ===== */
.download {
    max-width: 1100px;
    margin: 0 auto;
    padding: 40px 24px 96px;
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    max-width: 720px;
    margin: 0 auto;
}

.download-card h3 {
    font-size: 22px;
    margin-bottom: 16px;
}

.dl-meta {
    color: var(--color-text-secondary);
    font-size: 14px;
    margin-bottom: 6px;
}

.dl-version {
    color: var(--color-text-muted);
    font-size: 14px;
    margin-bottom: 24px;
}

.dl-hint {
    color: var(--color-text-muted);
    font-size: 13px;
    margin-top: 12px;
}

/* ===== 页脚 ===== */
.footer {
    background: #fff;
    border-top: 1px solid var(--color-divider);
    padding: 28px 24px;
}

.footer-inner {
    max-width: 1100px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    font-size: 14px;
    color: var(--color-text-secondary);
}

.footer-left {
    text-align: left;
}

.footer-center {
    text-align: center;
}

.footer-center a {
    color: var(--color-text-secondary);
    border-bottom: 1px solid var(--color-divider);
    padding-bottom: 2px;
}

.footer-center a:hover {
    color: var(--color-primary);
}

.footer-right {
    text-align: right;
    color: var(--color-text-muted);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 40px;
    }
    .hero-sub {
        font-size: 16px;
    }
    .feature-grid {
        grid-template-columns: 1fr;
    }
    .download-grid {
        grid-template-columns: 1fr;
    }
    .nav-menu {
        gap: 16px;
        font-size: 13px;
    }
    .footer-inner {
        grid-template-columns: 1fr;
        gap: 8px;
        text-align: center;
    }
    .footer-left,
    .footer-right {
        text-align: center;
    }
}