:root {
    --primary: #000000;
    --accent: #2563eb;
    --bg: #f8fafc;
    --white: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --radius-lg: 20px;
    --radius-md: 12px;
    --radius-sm: 8px;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
    --shadow-premium: 0 20px 25px -5px rgba(0,0,0,0.05), 0 10px 10px -5px rgba(0,0,0,0.04);
}

* {
    box-sizing: border-box;
}

body {
    background-color: var(--bg);
    font-family: 'Plus Jakarta Sans', -apple-system, blinkmacsystemfont, 'Segoe UI', roboto, sans-serif;
    color: var(--text-main);
    margin: 0;
    padding: 0;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

.checkout-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.checkout-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0 40px;
}

.back-link {
    display: flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 600;
    transition: all 0.2s;
}

.back-link:hover {
    color: var(--primary);
    transform: translateX(-2px);
}

.logo-link img {
    height: 28px;
    transition: opacity 0.2s;
}

.logo-link:hover img {
    opacity: 0.8;
}

/* Main Grid */
.checkout-grid {
    display: grid;
    grid-template-columns: 1fr 380px;
    gap: 32px;
    align-items: start;
}

@media (max-width: 1024px) {
    .checkout-grid {
        grid-template-columns: 1fr;
    }
}

/* Card General */
.card {
    background: var(--white);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-premium);
    margin-bottom: 24px;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    box-shadow: 0 25px 50px -12px rgba(0,0,0,0.08);
}

.card-body {
    padding: 32px;
}

@media (max-width: 640px) {
    .card-body {
        padding: 20px;
    }
}

/* Section Header */
.section-header {
    margin-bottom: 24px;
}

.section-title {
    font-size: 20px;
    font-weight: 800;
    margin: 0 0 4px;
    display: flex;
    align-items: center;
    gap: 10px;
    letter-spacing: -0.02em;
}

.section-title i {
    color: var(--accent);
    font-size: 0.9em;
}

.section-subtitle {
    color: var(--text-muted);
    font-size: 14px;
    margin: 0;
}

/* Product Card */
.product-hero {
    display: flex;
    gap: 24px;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.item-visual {
    flex-shrink: 0;
}

.product-image {
    width: 100px;
    height: 100px;
    border-radius: var(--radius-md);
    object-fit: cover;
    background: #f1f5f9;
    border: 1px solid var(--border);
}

.product-info {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.product-tag {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 10px;
    background: #eef2ff;
    color: var(--accent);
    border-radius: 100px;
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    margin-bottom: 8px;
    width: fit-content;
}

.product-title {
    font-size: 22px;
    font-weight: 800;
    margin: 0 0 4px;
    line-height: 1.2;
    letter-spacing: -0.01em;
}

.product-price {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary);
}

.product-description {
    font-size: 14px;
    color: var(--text-muted);
    line-height: 1.6;
}

@media (max-width: 480px) {
    .product-hero {
        flex-direction: column;
        gap: 16px;
    }
    .product-image {
        width: 80px;
        height: 80px;
    }
}

/* Forms */
.form-grid {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    gap: 16px 20px;
}

.form-group {
    grid-column: span 12;
}

.form-group.half { grid-column: span 6; }
.form-group.span-8 { grid-column: span 8; }
.form-group.span-4 { grid-column: span 4; }
.form-group.span-5 { grid-column: span 5; }
.form-group.span-3 { grid-column: span 3; }
.form-group.span-2 { grid-column: span 2; }
.form-group.span-6 { grid-column: span 6; }

@media (max-width: 640px) {
    .form-group.half, 
    .form-group.span-8, 
    .form-group.span-4, 
    .form-group.span-5, 
    .form-group.span-3,
    .form-group.span-2,
    .form-group.span-6 {
        grid-column: span 12;
    }
    
    /* Keep zip/city mini-grid on tablet if possible */
    .form-group.span-5 { grid-column: span 8; }
    .form-group.span-3 { grid-column: span 4; }
}

@media (max-width: 480px) {
    .form-group.span-5, .form-group.span-3 { grid-column: span 12; }
}

.form-label {
    display: block;
    font-size: 13px;
    font-weight: 700;
    margin-bottom: 6px;
    color: var(--text-main);
}

.form-label small {
    font-weight: 400;
    color: var(--text-muted);
}

.form-input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    color: var(--text-main);
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    background: #ffffff;
    font-family: inherit;
}

.form-input::placeholder {
    color: #94a3b8;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(0, 0, 0, 0.05);
}

.form-input.is-invalid {
    border-color: #ef4444;
    background-color: #fef2f2;
}

/* Autocomplete */
.form-group.full {
    position: relative;
}

.autocomplete-suggestions {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    margin-top: 5px;
    max-height: 240px;
    overflow-y: auto;
    display: none;
}

.autocomplete-suggestion {
    padding: 12px 16px;
    font-size: 14px;
    cursor: pointer;
    border-bottom: 1px solid #f1f5f9;
    transition: background 0.15s;
}

.autocomplete-suggestion:hover {
    background: #f8fafc;
}

.autocomplete-suggestion strong {
    color: var(--primary);
    font-weight: 700;
}

/* Toggle and Checkboxes */
.shipping-toggle-wrapper {
    margin: 24px 0;
    padding: 16px;
    background: #f8fafc;
    border-radius: var(--radius-md);
    border: 1px dashed var(--border);
}

.custom-checkbox {
    display: flex;
    align-items: center;
    position: relative;
    padding-left: 32px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    user-select: none;
}

.custom-checkbox input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    height: 20px;
    width: 20px;
    background-color: #fff;
    border: 2px solid var(--border);
    border-radius: 6px;
    transition: all 0.2s;
}

.custom-checkbox:hover input ~ .checkmark {
    border-color: var(--primary);
}

.custom-checkbox input:checked ~ .checkmark {
    background-color: var(--primary);
    border-color: var(--primary);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.custom-checkbox input:checked ~ .checkmark:after {
    display: block;
}

.checkbox-text {
    line-height: 1.4;
}

/* Sidebar Summary */
.summary-card {
    position: sticky;
    top: 20px;
}

.summary-details {
    padding: 10px 0;
}

.summary-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
    font-size: 15px;
    color: var(--text-muted);
}

.summary-row.total {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 2px solid #f1f5f9;
    color: var(--text-main);
    font-size: 26px;
    font-weight: 900;
    letter-spacing: -0.03em;
}

.summary-row .italic {
    font-style: italic;
    font-size: 0.85em;
    opacity: 0.7;
}

/* Actions */
.checkout-actions {
    margin-top: 24px;
}

.terms-checkbox {
    margin-bottom: 20px;
}

.terms-checkbox .checkbox-text {
    font-weight: 400;
    color: var(--text-muted);
}

.terms-checkbox a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}

.btn-submit {
    width: 100%;
    padding: 18px 24px;
    background: var(--primary);
    color: var(--white);
    border: none;
    border-radius: var(--radius-md);
    font-size: 16px;
    font-weight: 800;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 12px;
    box-shadow: 0 4px 14px rgba(0,0,0,0.15);
}

.btn-submit:hover {
    background: #1e293b;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.2);
}

.btn-submit:active {
    transform: translateY(0);
}

.btn-submit:disabled {
    background: #cbd5e1;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* Security Evidence */
.security-evidence {
    margin-top: 32px;
    text-align: center;
}

.security-text {
    font-size: 12px;
    color: var(--text-muted);
    margin-bottom: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 6px;
}

.payment-badges {
    display: flex;
    justify-content: center;
    gap: 16px;
    opacity: 0.6;
    filter: grayscale(1);
    transition: opacity 0.3s;
}

.payment-badges:hover {
    opacity: 0.9;
}

.payment-badges img {
    height: 20px;
}

.sidebar-help {
    margin-top: 20px;
    text-align: center;
}

.sidebar-help p {
    font-size: 13px;
    color: var(--text-muted);
}

.sidebar-help a {
    color: var(--primary);
    font-weight: 700;
    text-decoration: none;
}

/* Utils */
.italic { font-style: italic; }
.bold { font-weight: 700; }

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.checkout-main, .checkout-sidebar {
    animation: fadeInUp 0.6s cubic-bezier(0.2, 0.8, 0.2, 1) forwards;
}

.checkout-sidebar {
    animation-delay: 0.1s;
}