:root {
    --bg-color: #f4f5f7;
    --card-bg: #ffffff;
    --text-main: #1d1d1f;
    --text-muted: #86868b;
    --primary: #0071e3;
    --primary-hover: #0077ed;
    --border: #d2d2d7;
    --card-shadow: 0 4px 24px rgba(0,0,0,0.06);
    --radius: 16px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #000000;
        --card-bg: #1c1c1e;
        --text-main: #f5f5f7;
        --text-muted: #86868b;
        --primary: #2997ff;
        --primary-hover: #147ce5;
        --border: #38383a;
        --card-shadow: 0 4px 24px rgba(0,0,0,0.4);
    }
}

* {
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

a {
    text-decoration: none;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes modalPop {
    0% { opacity: 0; transform: scale(0.95); }
    100% { opacity: 1; transform: scale(1); }
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}
.header h2 {
    margin: 0;
    font-size: 24px;
}
.header a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    margin-left: 15px;
}
.announcement {
    background-color: var(--card-bg);
    padding: 20px;
    border-radius: var(--radius);
    margin-bottom: 20px;
    border: 1px solid var(--border);
    box-shadow: var(--card-shadow);
}
.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 24px;
    margin-bottom: 24px;
    box-shadow: var(--card-shadow);
    transition: background-color 0.3s, box-shadow 0.3s;
    animation: fadeIn 0.4s ease-out;
}

.modal-content {
    animation: modalPop 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.category-list {
    margin-bottom: 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}
.category-btn {
    display: inline-block;
    padding: 10px 20px;
    background: var(--card-bg);
    color: var(--text-main);
    text-decoration: none;
    border-radius: 24px;
    border: 1px solid var(--border);
    transition: all 0.2s;
    font-weight: 500;
}
.category-btn:hover, .category-btn.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}
.product-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 14px;
}
.card.product {
    background-color: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    transition: transform 0.2s, box-shadow 0.2s;
    text-decoration: none;
    color: var(--text-main);
    display: block;
    box-shadow: var(--card-shadow);
}
.card.product:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 32px rgba(0,0,0,0.1);
}
@media (prefers-color-scheme: dark) {
    .card.product:hover {
        box-shadow: 0 8px 32px rgba(0,0,0,0.6);
    }
}
.card h3 {
    margin: 0 0 10px 0;
    font-size: 20px;
}
.card .info {
    color: var(--text-muted);
    font-size: 14px;
    margin-bottom: 5px;
}
.card .price {
    color: #ff3b30;
    font-size: 20px;
    font-weight: bold;
    margin-top: 15px;
}
.form-group {
    margin-bottom: 20px;
}
.form-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-muted);
    font-weight: 500;
    text-align: left;
}

/* Payment Type UI */
.pay-methods {
    display: flex;
    gap: 15px;
    margin-bottom: 10px;
}
.pay-method-btn {
    flex: 1;
    background: var(--bg-color);
    border: 2px solid var(--border);
    border-radius: 12px;
    padding: 15px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 500;
    color: var(--text-main);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}
.pay-method-btn img, .pay-method-btn svg {
    width: 32px;
    height: 32px;
}
.pay-method-btn:hover {
    border-color: rgba(0,113,227,0.5);
    background: rgba(0,113,227,0.05);
}
.pay-method-btn.active {
    border-color: var(--primary);
    background: rgba(0,113,227,0.1);
    color: var(--primary);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    background-color: var(--bg-color);
    border: 1px solid var(--border);
    color: var(--text-main);
    border-radius: 12px;
    font-size: 16px;
    transition: border-color 0.2s;
}
.form-control:focus {
    border-color: var(--primary);
    outline: none;
    box-shadow: 0 0 0 3px rgba(0, 113, 227, 0.2);
}

textarea.form-control {
    resize: vertical;
}

.btn {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    text-align: center;
    transition: background-color 0.2s, transform 0.1s;
}
.btn:hover {
    background-color: #005bb5;
    transform: scale(1.02);
}
.btn:active {
    transform: scale(0.98);
}
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 20px;
}
table, th, td {
    border: 1px solid var(--border);
}
th, td {
    padding: 12px;
    text-align: left;
}
th {
    background-color: var(--bg-color);
}
.nav {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 20px;
}
.nav a {
    color: var(--text-main);
    text-decoration: none;
    padding: 10px 16px;
    background: var(--card-bg);
    border-radius: 12px;
    border: 1px solid var(--border);
    font-weight: 500;
    box-shadow: var(--card-shadow);
}
.nav a.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}
@media (max-width: 600px) {
    .container {
        padding: 15px;
    }
    .header {
        flex-direction: column;
        align-items: flex-start;
        gap: 15px;
    }
    .header div {
        margin-left: 0;
    }
    .header a {
        margin-left: 0;
        margin-right: 15px;
    }
    .product-grid {
        grid-template-columns: 1fr;
    }
}