:root {
    /* 黎明动态背景渐变色 */
    --bg-gradient: linear-gradient(-45deg, #a1c4fd, #c2e9fb, #ffecd2, #fcb69f);
    /* 按钮与高亮色 */
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --text-main: #1e293b;
    --text-muted: #64748b;
    /* 玻璃拟态卡片背景 */
    --glass-bg: rgba(255, 255, 255, 0.6);
    --glass-border: rgba(255, 255, 255, 0.8);
    --glass-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.07);
}

body {
    margin: 0;
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    color: var(--text-main);
    /* 动态黎明背景 */
    background: var(--bg-gradient);
    background-size: 400% 400%;
    animation: dawnGradient 15s ease infinite;
    min-height: 100vh;
    overflow-x: hidden;
}

@keyframes dawnGradient {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* 导航栏 */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.2rem 8%;
    background: rgba(255, 255, 255, 0.4);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: #333;
}
.logo .highlight { color: var(--primary-color); }

.nav-links { list-style: none; display: flex; gap: 2rem; margin: 0; padding: 0;}
.nav-links a { text-decoration: none; color: var(--text-main); font-weight: 500; transition: 0.3s; }
.nav-links a:hover { color: var(--primary-color); }

select {
    padding: 0.5rem;
    border-radius: 8px;
    border: 1px solid rgba(255,255,255,0.8);
    background: rgba(255,255,255,0.5);
    color: var(--text-main);
    font-weight: 600;
    outline: none;
    cursor: pointer;
}

/* 页面切换逻辑 */
.content-section {
    display: none;
    padding: 4rem 8%;
    animation: fadeIn 0.4s ease-out forwards;
}
.content-section.active { display: block; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: translateY(0); }
}

/* 首页 Hero */
.hero {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    min-height: 70vh;
}
.hero-text h1 {
    font-size: 4.5rem;
    margin-bottom: 1rem;
    background: linear-gradient(to right, #2563eb, #db2777);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}
.hero-text p {
    font-size: 1.25rem;
    color: var(--text-muted);
    max-width: 600px;
    margin: 0 auto 2.5rem auto;
    line-height: 1.6;
}
.hero-buttons { display: flex; gap: 1rem; justify-content: center; }

/* 按钮通用 */
.btn-primary, .btn-secondary, .btn-download {
    padding: 0.8rem 2.5rem;
    border-radius: 50px;
    border: none;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
}
.btn-primary { background: var(--primary-color); color: white; box-shadow: 0 4px 15px rgba(79, 70, 229, 0.3); }
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-2px); }
.btn-secondary { background: rgba(255,255,255,0.6); color: var(--text-main); border: 1px solid white; }
.btn-secondary:hover { background: white; transform: translateY(-2px); }

/* 下载页 */
.section-header { text-align: center; margin-bottom: 3rem; }
.section-header h2 { font-size: 2.5rem; color: #1e293b; margin-bottom: 0.5rem; }
.section-header p { color: var(--text-muted); font-size: 1.1rem; }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 2rem;
}

/* 玻璃拟态卡片 */
.card {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 2.5rem 1.5rem;
    text-align: center;
    box-shadow: var(--glass-shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.card:hover { transform: translateY(-10px); box-shadow: 0 12px 40px 0 rgba(31, 38, 135, 0.15); }

.card-icon {
    width: 70px;
    height: 70px;
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    margin: 0 auto 1.5rem auto;
    color: white;
}
.win { background: linear-gradient(135deg, #0078D7, #00b4ff); }
.mac { background: linear-gradient(135deg, #555, #222); }
.and { background: linear-gradient(135deg, #3DDC84, #1b9e54); }
.lin { background: linear-gradient(135deg, #F5A900, #d48e00); }

.card h3 { margin: 0 0 0.5rem 0; font-size: 1.5rem; }
.version { color: var(--text-muted); font-size: 0.9rem; margin-bottom: 1.5rem; }

.btn-download {
    display: block;
    background: var(--primary-color);
    color: white;
    padding: 0.7rem;
    font-size: 1rem;
    margin-bottom: 1rem;
}
.btn-download:hover { background: var(--primary-hover); color: white; }

.link-alt {
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
}
.link-alt:hover { text-decoration: underline; }

/* 教程步骤 */
.tutorial-container { max-width: 800px; margin: 0 auto; }
.step {
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    backdrop-filter: blur(12px);
    padding: 2rem;
    border-radius: 20px;
    margin-bottom: 1.5rem;
    box-shadow: var(--glass-shadow);
}
.step-num {
    background: var(--primary-color);
    color: white;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: bold;
    flex-shrink: 0;
}
.step-content h4 { margin: 0 0 0.5rem 0; font-size: 1.25rem; color: #1e293b; }
.step-content p { margin: 0; color: var(--text-muted); line-height: 1.5; }