/* Shared Variables & Reset */
:root {
    --primary: #0ea5e9;
    --primary-dark: #0284c7;
    --secondary: #6366f1;
    --accent: #06b6d4;
    --dark-bg: #0f172a;
    --section-bg: #1e293b;
    --card-bg: rgba(30, 41, 59, 0.6);
    --text-light: #f8fafc;
    --text-dim: #cbd5e1;
    --text-gray: #94a3b8;
    --gradient-main: linear-gradient(135deg, #0ea5e9 0%, #6366f1 100%);
    --glass: rgba(15, 23, 42, 0.85);
    --glass-border: rgba(255, 255, 255, 0.08);
    --container-width: 1200px;
}

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

body {
    font-family: 'Inter', 'Noto Sans TC', sans-serif;
    background-color: var(--dark-bg);
    color: var(--text-light);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

ul {
    list-style: none;
}

/* Layout Utilities */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header (Consistent with other pages) */
header {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    padding: 1rem 0;
    background: var(--glass);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--glass-border);
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    background: var(--gradient-main);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo::before {
    content: '';
    display: block;
    width: 28px;
    height: 28px;
    background: var(--gradient-main);
    border-radius: 6px;
    transform: rotate(45deg);
}

nav ul {
    display: flex;
    gap: 2.5rem;
}

nav a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-dim);
    position: relative;
}

nav a:hover,
nav a.active {
    color: var(--text-light);
}

/* Active underline indicator */
nav a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary);
    box-shadow: 0 0 10px var(--primary);
}

/* Page Hero */
.page-hero {
    padding: 160px 0 60px;
    background: radial-gradient(circle at 50% 0%, rgba(14, 165, 233, 0.15), transparent 60%);
    text-align: center;
    margin-bottom: 4rem;
}

.page-hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.page-hero p {
    font-size: 1.2rem;
    color: var(--text-dim);
    max-width: 600px;
    margin: 0 auto;
}

/* Filter Categories */
.filter-section {
    margin-bottom: 4rem;
}

.filter-list {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.filter-btn {
    padding: 0.75rem 1.5rem;
    background: rgba(30, 41, 59, 0.5);
    border: 1px solid var(--glass-border);
    border-radius: 50px;
    color: var(--text-dim);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
    box-shadow: 0 0 15px rgba(14, 165, 233, 0.3);
    transform: translateY(-2px);
}

/* Product Grid (Card Wall) */
.product-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
    margin-bottom: 6rem;
}

.product-card {
    background: var(--card-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    overflow: hidden;
    transition: all 0.4s ease;
    display: flex;
    flex-direction: column;
    position: relative;
}

.product-card:hover {
    transform: translateY(-10px);
    border-color: var(--primary);
    box-shadow: 0 20px 40px -10px rgba(0, 0, 0, 0.5);
    background: rgba(30, 41, 59, 0.9);
}

.product-img-wrapper {
    width: 100%;
    height: 200px;
    background: #020617;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    position: relative;
}

/* Placeholder graphic for products */
.product-placeholder {
    width: 80px;
    height: 80px;
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: rgba(255, 255, 255, 0.2);
    transition: 0.3s;
}

.product-card:hover .product-placeholder {
    border-color: var(--accent);
    color: var(--accent);
    transform: scale(1.1);
}

.product-content {
    padding: 1.5rem;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.product-category {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--accent);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.product-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-light);
    line-height: 1.4;
}

.product-specs {
    margin-bottom: 1rem;
    padding-left: 1.2rem;
}

.product-specs li {
    font-size: 0.9rem;
    color: var(--text-dim);
    margin-bottom: 0.4rem;
    list-style-type: disc;
}

.usage-scenario {
    font-size: 0.9rem;
    color: var(--text-gray);
    margin-bottom: 1.5rem;
    padding: 0.75rem;
    background: rgba(15, 23, 42, 0.6);
    border-radius: 8px;
    border-left: 3px solid var(--secondary);
    font-style: italic;
    flex-grow: 1;
}

.btn-card {
    display: inline-block;
    width: 100%;
    padding: 0.8rem 0;
    text-align: center;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    border-radius: 10px;
    color: var(--text-light);
    font-weight: 600;
    font-size: 0.95rem;
    transition: 0.3s;
}

.btn-card:hover {
    background: var(--gradient-main);
    border-color: transparent;
    color: white;
}

/* Footer (Consistent) */
footer {
    background: #020617;
    padding: 5rem 0 2rem;
    border-top: 1px solid var(--glass-border);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1.5fr;
    gap: 3rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    padding-bottom: 3rem;
    margin-bottom: 2rem;
}

.footer-col h4 {
    color: var(--text-light);
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.contact-list li {
    margin-bottom: 1rem;
    color: var(--text-gray);
    display: flex;
    gap: 12px;
    align-items: flex-start;
}

.copyright {
    text-align: center;
    color: #475569;
    font-size: 0.875rem;
}

/* Responsive Breakpoints */
@media (max-width: 1200px) {
    .product-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 900px) {
    .product-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .page-hero h1 {
        font-size: 2.5rem;
    }
}

@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }

    nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1.5rem;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 2.5rem;
    }

    .product-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
}