:root {
    --ios-background: #F2F2F7;
    --ios-primary: #ff9900;
    --ios-secondary: #5856D6;
    --ios-success: #34C759;
    --ios-warning: #FF9500;
    --ios-danger: #FF3B30;
    --ios-card-bg: rgba(255,255,255,0.8);
    --ios-card-shadow: 0 4px 12px rgba(0,0,0,0.05);
    --ios-radius: 20px;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Helvetica", "Arial", sans-serif;
    background: var(--ios-background);
    color: #1c1c1e;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background: #fff;
    color: #333;
}

header {
    background: #333;
    color: #fff;
    padding: 1rem 0;
    text-align: center;
}

header h1 {
    margin: 0;
}

nav ul {
    padding: 0;
    list-style: none;
}

nav ul li {
    display: inline;
    margin-right: 20px;
}

nav a {
    color: #fff;
    text-decoration: none;
}

.container {
    padding: 2rem 1rem;
    max-width: 960px;
    margin: 0 auto;
}

#hero {
    display: flex;
    align-items: center;
    padding: 2rem 1rem;
    background: var(--ios-card-bg);
    border-radius: var(--ios-radius);
    box-shadow: var(--ios-card-shadow);
}

.hero-content {
    flex: 1;
    padding-right: 2rem;
}

.hero-image {
    flex: 1;
    text-align: center;
}

.hero-image img {
    max-width: 100%;
    height: auto;
    border-radius: 10px;
}

#hero h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.cta-button {
    display: inline-block;
    background: var(--ios-primary);
    color: #fff;
    padding: 12px 25px;
    text-decoration: none;
    border-radius: var(--ios-radius);
    margin-top: 1rem;
    font-weight: bold;
    transition: background-color 0.3s ease;
    box-shadow: 0 4px 8px rgba(0,122,255,0.25);
    transition: transform 0.2s cubic-bezier(.25,.8,.25,1);
    box-shadow: 0 4px 10px rgba(255,153,0,0.25);
}

.cta-button:hover {
    background: #e68a00;
    transform: translateY(-2px);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.feature-item {
    text-align: center;
}

#how-it-works {
    background: #f9f9f9;
}

.review {
    background: #f4f4f4;
    border-left: 5px solid #ff9900;
    padding: 1.5rem;
    margin-bottom: 1rem;
}

.review span {
    font-style: italic;
    font-weight: bold;
}

.cta-section {
    background: #333;
    color: #fff;
    text-align: center;
    padding: 3rem 1rem;
}

footer {
    text-align: center;
    padding: 1rem 0;
    background: #333;
    color: #fff;
    width: 100%;
}

/* Products Section */
#products {
    text-align: center;
}

.product-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.product-item {
    background: #f9f9f9;
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.product-item img {
    max-width: 100%;
    height: auto;
    border-radius: 10px;
    margin-bottom: 1rem;
}

.product-item h3 {
    margin-bottom: 0.5rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    header nav ul li {
        display: block;
        margin: 10px 0;
    }

    #hero {
        flex-direction: column;
        text-align: center;
    }

    .hero-content {
        padding-right: 0;
        margin-bottom: 2rem;
    }

    .feature-grid {
        grid-template-columns: 1fr;
    }

    .product-grid {
        grid-template-columns: 1fr;
    }
    /* ========== Desktop fixed header ========== */
    @media (min-width: 1024px) {
        header {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            z-index: 999;
            /* 可选：加边框或阴影以增强分隔感 */
            box-shadow: 0 2px 6px rgba(0,0,0,0.08);
        }
    
        /* 为正文留出与 header 相同高度的空隙，避免被遮挡 */
        body {
            padding-top: 80px; /* 若 header 高度不同，请同步修改 */
        }
    }
    /* ========== END Desktop fixed header ========== */
}