:root {
    /* 全局深色科技主题变量 */
    --canvas-bg: #0b0e14;
    --surface-bg: rgba(18, 22, 28, 0.82);
    --surface-border: rgba(255, 255, 255, 0.08);
    --stroke-color: rgba(255, 255, 255, 0.06);
    --accent-glow: linear-gradient(135deg, rgba(99, 102, 241, 0.25) 0%, rgba(6, 182, 212, 0.18) 100%);
    --text-main: #eef2f6;
    --text-muted: #94a3b8;
    --text-accent: #38bdf8;
    --brand-gradient: linear-gradient(135deg, #6366f1 0%, #06b6d4 50%, #a855f7 100%);
    --card-radius: 20px;
    --section-gap: 100px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--canvas-bg);
    color: var(--text-main);
    line-height: 1.7;
    overflow-x: hidden;
    position: relative;
}

/* 全局氛围光 */
body::before,
body::after {
    content: "";
    position: fixed;
    z-index: -1;
    pointer-events: none;
    border-radius: 50%;
}
body::before {
    top: -10%;
    left: -6%;
    width: 58vw;
    height: 58vw;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.18) 0%, rgba(11, 14, 20, 0) 70%);
}
body::after {
    bottom: -6%;
    right: -6%;
    width: 48vw;
    height: 48vw;
    background: radial-gradient(circle, rgba(6, 182, 212, 0.13) 0%, rgba(11, 14, 20, 0) 70%);
}

/* ========== 导航栏 ========== */
.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(11, 14, 20, 0.82);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    height: 72px;
    animation: fadeIn 0.7s ease both;
}
.navbar-container {
    max-width: 1400px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 48px;
}
.nav-brand a {
    text-decoration: none;
    color: var(--text-main);
    font-size: 19px;
    font-weight: 800;
    display: flex;
    align-items: center;
    gap: 10px;
    letter-spacing: -0.4px;
}
.nav-brand img {
    width: 30px;
    height: 30px;
    object-fit: contain;
}
.nav-right-zone {
    display: flex;
    align-items: center;
    gap: 20px;
}
.nav-menu {
    display: flex;
    gap: 4px;
}
.nav-item {
    text-decoration: none;
    color: var(--text-muted);
    font-size: 13.5px;
    font-weight: 600;
    padding: 7px 16px;
    border-radius: 9px;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}
.nav-item:hover {
    color: var(--text-accent);
    background: rgba(56, 189, 248, 0.08);
}
.nav-item.active {
    color: #fff;
    background: #1e293b;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.3);
}
.btn-github {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    padding: 7px 15px;
    border-radius: 9px;
    background: #1e293b;
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-main);
    text-decoration: none;
    font-size: 13px;
    font-weight: 600;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
    transition: all 0.25s ease;
}
.btn-github:hover {
    background: #334155;
    border-color: rgba(255, 255, 255, 0.18);
    transform: translateY(-1px);
}
.btn-github svg {
    width: 15px;
    height: 15px;
    fill: currentColor;
}

/* ========== 按钮系统 ========== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 13px 28px;
    border-radius: 11px;
    font-size: 14.5px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    white-space: nowrap;
}
.btn-primary {
    background: var(--brand-gradient);
    color: #fff;
    box-shadow: 0 7px 26px rgba(99, 102, 241, 0.4);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 11px 32px rgba(99, 102, 241, 0.55);
}
.btn-secondary {
    background: #1e293b;
    color: var(--text-main);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 3px 16px rgba(0, 0, 0, 0.3);
}
.btn-secondary:hover {
    background: #334155;
    transform: translateY(-2px);
}

/* ========== 通用标题组件 ========== */
.section-header {
    text-align: center;
    margin-bottom: 48px;
}
.section-eyebrow {
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1.6px;
    color: var(--text-accent);
    margin-bottom: 10px;
    display: block;
}
.section-title {
    font-size: 34px;
    font-weight: 900;
    letter-spacing: -1px;
    color: var(--text-main);
    margin-bottom: 14px;
}
.section-desc {
    font-size: 15px;
    color: var(--text-muted);
    max-width: 680px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ========== 下载页 Hero ========== */
.download-hero {
    padding: 48px 48px 0;
    text-align: center;
    max-width: 1400px;
    margin: 0 auto;
}
.download-hero .hero-title {
    font-size: 44px;
    font-weight: 900;
    letter-spacing: -1.5px;
    background: linear-gradient(135deg, #eef2f6 20%, #6366f1 50%, #06b6d4 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 12px;
}
.download-hero .hero-subtitle {
    font-size: 16px;
    max-width: 680px;
    margin: 0 auto 28px;
    color: var(--text-muted);
    line-height: 1.75;
}

/* ========== 平台下载卡片网格 ========== */
.platform-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    max-width: 1200px;
    margin: 0 auto 80px;
    padding: 0 48px;
}
.platform-card {
    background: #1e293b;
    border: 1px solid rgba(255,255,255,0.06);
    border-radius: var(--card-radius);
    padding: 32px 24px;
    text-align: center;
    box-shadow: 0 8px 24px rgba(0,0,0,0.4);
    transition: transform 0.3s ease, border-color 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
}
.platform-card:hover {
    transform: translateY(-6px);
    border-color: rgba(56,189,248,0.3);
}
.platform-icon {
    width: 64px;
    height: 64px;
    border-radius: 18px;
    background: rgba(99,102,241,0.15);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-accent);
}
.platform-name {
    font-size: 20px;
    font-weight: 800;
    color: var(--text-main);
}
.platform-arch {
    font-size: 13px;
    color: var(--text-muted);
    margin-bottom: 8px;
}
.platform-meta {
    font-size: 12px;
    color: #94a3b8;
    display: flex;
    flex-direction: column;
    gap: 4px;
}
.btn-download {
    margin-top: 8px;
    background: var(--brand-gradient);
    color: #fff;
    padding: 12px 26px;
    border-radius: 10px;
    font-weight: 700;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 6px 20px rgba(99,102,241,0.35);
    transition: all 0.3s ease;
}
.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 28px rgba(99,102,241,0.5);
}
.checksum-box {
    background: #0f172a;
    border: 1px solid rgba(255,255,255,0.08);
    border-radius: 16px;
    padding: 20px 24px;
    margin-top: 16px;
    font-size: 12px;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
    width: 100%;
    box-sizing: border-box;
}
.checksum-box code {
    background: #1e293b;
    padding: 4px 10px;
    border-radius: 6px;
    color: var(--text-accent);
    font-family: monospace;
    font-size: 12px;
}

/* ========== 安装步骤 ========== */
.install-steps {
    max-width: 1000px;
    margin: 0 auto 80px;
    padding: 0 48px;
    display: flex;
    flex-direction: column;
    gap: 28px;
}
.install-step {
    display: flex;
    align-items: flex-start;
    gap: 20px;
}
.step-num {
    width: 40px;
    height: 40px;
    background: var(--brand-gradient);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 900;
    color: #fff;
    flex-shrink: 0;
}
.step-content h3 {
    font-size: 18px;
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 6px;
}
.step-content p {
    font-size: 14px;
    color: var(--text-muted);
    line-height: 1.6;
}
.step-content code {
    background: #334155;
    padding: 2px 8px;
    border-radius: 5px;
    font-family: monospace;
    font-size: 13px;
}

/* ========== 下载 FAQ ========== */
.faq-inline {
    max-width: 900px;
    margin: 0 auto 80px;
    padding: 0 48px;
}
.faq-item {
    background: #1e293b;
    border: 1px solid rgba(255,255,255,0.05);
    border-radius: 16px;
    padding: 22px 24px;
    margin-bottom: 16px;
}
.faq-item h3 {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: 8px;
}
.faq-item p {
    font-size: 13.5px;
    color: var(--text-muted);
    line-height: 1.65;
}
.faq-item code {
    background: #334155;
    padding: 2px 8px;
    border-radius: 5px;
    font-family: monospace;
    font-size: 12.5px;
}

/* ========== 底部 CTA ========== */
.bottom-cta {
    max-width: 1400px;
    margin: 0 auto 100px;
    padding: 0 48px;
    text-align: center;
}
.cta-bottom-title {
    font-size: 30px;
    font-weight: 900;
    letter-spacing: -0.8px;
    color: var(--text-main);
    margin-bottom: 12px;
}
.cta-bottom-text {
    font-size: 15px;
    color: var(--text-muted);
    margin-bottom: 28px;
}
.cta-group {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 14px;
    flex-wrap: wrap;
}

/* ========== Footer ========== */
.footer {
    background-color: #0f172a;
    color: var(--text-muted);
    padding: 64px 48px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    position: relative;
    z-index: 2;
}
.footer-container {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.6fr 1fr 1fr;
    gap: 52px;
}
.footer-brand-side {
    display: flex;
    flex-direction: column;
    gap: 14px;
}
.footer-brand-title {
    font-size: 15px;
    font-weight: 800;
    color: var(--text-main);
}
.footer-text {
    font-size: 12.5px;
    color: var(--text-muted);
    line-height: 1.6;
}
.footer-nav-col {
    display: flex;
    flex-direction: column;
    gap: 14px;
}
.footer-col-title {
    font-size: 13px;
    font-weight: 700;
    color: var(--text-main);
    letter-spacing: 0.4px;
}
.footer-links-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
    list-style: none;
}
.footer-links-list a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 12.5px;
    font-weight: 500;
    transition: color 0.2s ease;
}
.footer-links-list a:hover {
    color: var(--text-accent);
}

/* ========== 动画 ========== */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(28px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
    .download-hero .hero-title { font-size: 36px; }
    .section-title { font-size: 28px; }
    .footer-container { grid-template-columns: 1fr 1fr; gap: 36px; }
}

@media (max-width: 768px) {
    .navbar-container { padding: 0 20px; }
    .nav-menu { display: none; }
    .platform-grid { padding: 0 20px; grid-template-columns: 1fr; }
    .install-steps { padding: 0 20px; }
    .faq-inline { padding: 0 20px; }
    .download-hero { padding: 32px 20px 0; }
    .download-hero .hero-title { font-size: 30px; }
    .section-title { font-size: 24px; }
    .bottom-cta { padding: 0 20px; margin-bottom: 60px; }
    .footer-container { grid-template-columns: 1fr; gap: 28px; }
    .footer { padding: 48px 24px; }
    .btn { padding: 12px 22px; font-size: 13.5px; }
    .platform-card { padding: 24px 20px; }
    .checksum-box { flex-direction: column; text-align: center; }
}