:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --text-main: #1f2937;
    --text-muted: #6b7280;
    --bg-main: #f3f4f6;
    --card-bg: #ffffff;
    --border-color: #e5e7eb;
    --error-color: #ef4444;
    --success-color: #10b981;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.5;
    padding: 2rem 1rem;
}

.checkout-container {
    max-width: 600px;
    margin: 0 auto;
}

.checkout-card {
    background-color: var(--card-bg);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
}

.checkout-title {
    font-size: 1.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    text-transform: uppercase;
}

.product-img {
    max-width: 100%;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.product-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    text-align: center;
}

.quantity-control {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.quantity-control .label {
    font-weight: 500;
}

.qty-btn-group {
    display: flex;
    align-items: center;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    overflow: hidden;
}

.qty-btn {
    background: #f9fafb;
    border: none;
    width: 36px;
    height: 36px;
    font-size: 1.2rem;
    cursor: pointer;
    color: var(--text-main);
    transition: background 0.2s;
}

.qty-btn:hover {
    background: #e5e7eb;
}

#quantity {
    width: 50px;
    height: 36px;
    border: none;
    border-left: 1px solid var(--border-color);
    border-right: 1px solid var(--border-color);
    text-align: center;
    font-weight: 600;
    font-size: 1rem;
    color: var(--text-main);
    -moz-appearance: textfield;
}

#quantity::-webkit-outer-spin-button,
#quantity::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.voucher-section {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

.voucher-section input {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.95rem;
    outline: none;
    transition: border-color 0.2s;
}

.voucher-section input:focus {
    border-color: var(--primary-color);
}

.voucher-section button {
    background-color: var(--text-main);
    color: white;
    border: none;
    padding: 0 1.5rem;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

.voucher-section button:hover {
    background-color: #374151;
}

.message {
    font-size: 0.85rem;
    margin-bottom: 1.5rem;
    min-height: 1.2rem;
    font-weight: 500;
}

.msg-error { color: var(--error-color); }
.msg-success { color: var(--success-color); }

.summary-table {
    background: #f9fafb;
    border-radius: 8px;
    padding: 1.25rem;
    margin-bottom: 1.5rem;
}

.summary-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.75rem;
    font-size: 0.95rem;
    color: var(--text-muted);
}

.summary-row:last-child {
    margin-bottom: 0;
}

.total-row {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px dashed var(--border-color);
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-main);
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
}

.required {
    color: var(--error-color);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.95rem;
    font-family: inherit;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.form-checkbox {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.form-checkbox input[type="checkbox"] {
    margin-top: 0.25rem;
    cursor: pointer;
}

.form-checkbox label {
    font-size: 0.9rem;
    color: var(--text-muted);
    cursor: pointer;
    line-height: 1.4;
}

.submit-btn {
    width: 100%;
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
    box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.3);
    margin-bottom: 1rem;
}

.submit-btn:hover {
    background-color: var(--primary-hover);
}

.submit-btn:active {
    transform: scale(0.98);
}

.submit-btn:disabled {
    background-color: #9ca3af;
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}