:root {
    --primary-color: #007fff;
    --primary-dark: #0056b3;
    --secondary-color: #333;
    --bg-light: #f8f9fa;
    --text-color: #444;
    --text-muted: #666;
    --white: #ffffff;
    --shadow: 0 4px 20px rgba(0,0,0,0.08);
}

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

body {
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background: #fff;
    padding-bottom: 70px; /* Space for sticky footer on mobile */
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* Header & Nav */
header {
    background: var(--white);
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

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

.logo { font-size: 24px; font-weight: 800; color: var(--primary-color); letter-spacing: -1px; }

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

.nav-links li { margin-left: 30px; }

.nav-links li a {
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: 500;
    transition: color 0.3s;
}

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

/* Breadcrumb */
.breadcrumb { padding: 20px 0; font-size: 14px; color: var(--text-muted); }
.breadcrumb a { color: var(--text-muted); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }

/* Hero Section */
.hero {
    background: linear-gradient(rgba(0,127,255,0.8), rgba(0,127,255,0.9)), url('assets/hero-bg.jpg');
    background-size: cover;
    background-position: center;
    color: #fff;
    padding: 100px 0;
    text-align: center;
}

.hero h1 { font-size: 56px; margin-bottom: 20px; font-weight: 800; }

.subtitle { font-size: 22px; margin-bottom: 40px; opacity: 0.9; font-weight: 300; }

.cta-buttons .btn { margin: 0 10px; padding: 15px 40px; font-size: 18px; }

.btn {
    display: inline-block;
    border-radius: 8px;
    text-decoration: none;
    font-weight: bold;
    transition: all 0.3s ease;
    cursor: pointer;
}

.btn-primary { background: var(--white); color: var(--primary-color); box-shadow: 0 4px 15px rgba(0,0,0,0.1); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(0,0,0,0.15); }

.btn-secondary { background: transparent; border: 2px solid var(--white); color: var(--white); }
.btn-secondary:hover { background: rgba(255,255,255,0.1); }

.version-tag { margin-top: 30px; font-size: 14px; opacity: 0.7; }

/* Section Common */
.section-title { text-align: center; font-size: 36px; margin-bottom: 50px; position: relative; padding-bottom: 15px; }
.section-title::after { content: ''; position: absolute; bottom: 0; left: 50%; transform: translateX(-50%); width: 60px; height: 4px; background: var(--primary-color); }

.section-desc { text-align: center; color: var(--text-muted); margin-top: -40px; margin-bottom: 50px; font-size: 18px; }

/* News Section */
.news-section { padding: 100px 0; }
.news-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; }
.news-item { background: #fff; padding: 30px; border-radius: 10px; box-shadow: 0 5px 15px rgba(0,0,0,0.05); }
.news-date { font-size: 14px; color: var(--primary-color); font-weight: bold; }
.news-item h3 { margin: 10px 0; font-size: 20px; }
.news-item p { color: var(--text-muted); }

/* Download Grid */
.download-section { padding: 100px 0; }
.download-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(350px, 1fr)); gap: 40px; }

.card {
    background: var(--white);
    padding: 50px;
    border-radius: 15px;
    box-shadow: var(--shadow);
    text-align: center;
    border: 1px solid #eee;
    transition: transform 0.3s;
}
.card:hover { transform: translateY(-10px); }

.card-icon { font-size: 50px; margin-bottom: 20px; }

.card h3 { font-size: 24px; margin-bottom: 15px; }

.card-features { list-style: none; margin: 25px 0; text-align: left; padding-left: 20px; }
.card-features li { margin-bottom: 10px; position: relative; color: var(--text-muted); }
.card-features li::before { content: '✓'; position: absolute; left: -25px; color: var(--primary-color); font-weight: bold; }

.btn-dl { background: var(--primary-color); color: var(--white); width: 100%; margin-top: 10px; }
.btn-dl:hover { background: var(--primary-dark); }

/* Specs Section */
.specs-section { padding: 100px 0; }
.specs-table-wrapper { overflow-x: auto; background: #fff; border-radius: 10px; box-shadow: var(--shadow); }
.specs-table { width: 100%; border-collapse: collapse; min-width: 600px; }
.specs-table th, .specs-table td { padding: 20px; text-align: left; border-bottom: 1px solid #eee; }
.specs-table th { background: #f0f7ff; color: var(--primary-color); }

/* Security Section */
.bg-light { background: var(--bg-light); }
.security-section { padding: 100px 0; }
.security-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; }

.security-item { background: #fff; padding: 40px; border-radius: 10px; text-align: center; box-shadow: 0 5px 15px rgba(0,0,0,0.03); }
.security-icon { font-size: 40px; margin-bottom: 15px; }
.security-item h3 { color: var(--primary-color); margin-bottom: 15px; }

/* Partners */
.partners { padding: 100px 0; }
.partner-logos { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 20px; }

.logo-item {
    background: #f0f4f8;
    padding: 20px;
    text-align: center;
    border-radius: 8px;
    color: #94a3b8;
    font-weight: bold;
    font-size: 14px;
}

/* Floating Sidebar */
.floating-sidebar {
    position: fixed;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    flex-direction: column;
    gap: 10px;
    z-index: 1001;
}

.side-item {
    background: var(--white);
    color: var(--primary-color);
    padding: 15px;
    border-radius: 50%;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    font-size: 12px;
    font-weight: bold;
    text-decoration: none;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.3s;
    line-height: 1.2;
}

.side-item:hover { background: var(--primary-color); color: var(--white); }
.back-to-top { font-size: 24px; }

/* Sticky Footer */
.sticky-footer {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background: var(--white);
    box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
    padding: 10px 20px;
    z-index: 1002;
}

.sticky-wrap { display: flex; justify-content: space-between; align-items: center; }
.sticky-wrap span { font-weight: bold; color: var(--secondary-color); }
.btn-sticky { background: var(--primary-color); color: var(--white); padding: 10px 25px; border-radius: 50px; text-decoration: none; font-weight: bold; }

/* Footer */
footer { background: #1a202c; color: #a0aec0; padding: 80px 0 30px; }
.footer-content { display: grid; grid-template-columns: 2fr 1fr; gap: 50px; }
.footer-info h3 { color: #fff; margin-bottom: 20px; }
.footer-links h4, .footer-hub h4 { color: #fff; margin-bottom: 15px; font-size: 16px; }
.footer-links { display: flex; flex-direction: column; gap: 10px; }
.hub-links { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.hub-links a, .footer-links a { color: #a0aec0; text-decoration: none; transition: color 0.3s; font-size: 14px; }
.hub-links a:hover, .footer-links a:hover { color: #fff; }
.copyright { grid-column: 1 / -1; text-align: center; padding-top: 50px; margin-top: 50px; border-top: 1px solid #2d3748; font-size: 12px; }
.copyright time { color: var(--primary-color); font-weight: bold; }

/* 404 & Download Specific Styles */
.status-page { padding: 150px 0; text-align: center; }
.status-page h1 { font-size: 120px; color: var(--primary-color); margin-bottom: 20px; }
.status-page p { font-size: 24px; margin-bottom: 40px; color: var(--text-muted); }

.download-page { padding: 100px 0; }
.dl-options { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 30px; margin-top: 50px; }
.dl-card { background: #fff; padding: 40px; border-radius: 12px; box-shadow: var(--shadow); text-align: center; }
.dl-card h3 { margin-bottom: 20px; }
.dl-card .btn { width: 100%; margin-top: 20px; }

@media (max-width: 768px) {
    .hero h1 { font-size: 36px; }
    .nav-links { display: none; }
    .footer-content { grid-template-columns: 1fr; }
    .floating-sidebar { display: none; }
    .sticky-footer { display: block; }
}