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

        :root {
            --text: #0a0a0a;
            --muted: #666;
            --bg: #ffffff;
            --bg-subtle: #fafafa;
            --border: #f0f0f0;
            --accent: #0a0a0a;
            --success: #2e7d32;
        }

        body {
            font-family: 'Inter', sans-serif;
            background: var(--bg);
            color: var(--text);
            line-height: 1.6;
            font-weight: 300;
        }

        /* Header */
        header {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(20px);
            padding: 2rem 5%;
            border-bottom: 1px solid var(--border);
        }

        nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
            max-width: 1400px;
            margin: 0 auto;
        }

        .logo {
            font-size: 1.1rem;
            font-weight: 600;
            letter-spacing: 3px;
            text-transform: uppercase;
        }

        .back-link {
            color: var(--text);
            text-decoration: none;
            font-weight: 400;
            transition: opacity 0.3s;
        }

        .back-link:hover {
            opacity: 0.6;
        }

        /* Container */
        .checkout-container {
            max-width: 1400px;
            margin: 0 auto;
            padding: 4rem 5%;
        }

        /* Progress Steps */
        .progress-steps {
            display: flex;
            justify-content: center;
            align-items: center;
            gap: 2rem;
            margin-bottom: 4rem;
        }

        .step {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            color: var(--muted);
            font-size: 0.9rem;
            font-weight: 400;
        }

        .step-number {
            width: 36px;
            height: 36px;
            border-radius: 50%;
            border: 2px solid var(--border);
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 500;
        }

        .step.active {
            color: var(--text);
        }

        .step.active .step-number {
            background: var(--accent);
            color: white;
            border-color: var(--accent);
        }

        .step.completed .step-number {
            background: var(--success);
            color: white;
            border-color: var(--success);
        }

        .step-arrow {
            color: var(--border);
            font-size: 1.5rem;
        }

        /* Main Grid */
        .checkout-grid {
            display: grid;
            grid-template-columns: 1.5fr 1fr;
            gap: 4rem;
            align-items: start;
        }

        /* Left Column - Forms */
        .checkout-main {
            display: flex;
            flex-direction: column;
            gap: 2rem;
        }

        .section {
            background: var(--bg-subtle);
            padding: 2.5rem;
            border-radius: 12px;
        }

        .section.hidden {
            display: none;
        }

        .section-title {
            font-size: 1.5rem;
            font-weight: 500;
            margin-bottom: 1.5rem;
            letter-spacing: 0.3px;
        }

        /* Form Fields */
        .field {
            margin-bottom: 1.25rem;
        }

        .field label {
            display: block;
            font-size: 0.9rem;
            margin-bottom: 0.5rem;
            color: var(--muted);
            font-weight: 400;
        }

        .field input,
        .field textarea {
            width: 100%;
            padding: 1rem;
            border: 1px solid var(--border);
            border-radius: 8px;
            font-size: 1rem;
            font-family: inherit;
            background: white;
            transition: border-color 0.3s;
        }

        .field input:focus,
        .field textarea:focus {
            outline: none;
            border-color: var(--accent);
        }

        .field-row {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1rem;
        }

        /* Cart Items in Step 1 */
        .cart-items-list {
            display: flex;
            flex-direction: column;
            gap: 1rem;
            margin-bottom: 2rem;
        }

        .cart-item-mini {
            display: flex;
            align-items: center;
            gap: 1rem;
            padding: 1rem;
            background: white;
            border-radius: 8px;
        }

        .cart-item-mini img {
            width: 60px;
            height: 60px;
            object-fit: cover;
            border-radius: 6px;
            background: #e8e8e8;
        }

        .cart-item-mini .info {
            flex: 1;
        }

        .cart-item-mini .info h4 {
            font-size: 1rem;
            font-weight: 500;
            margin-bottom: 0.25rem;
        }

        .cart-item-mini .info .details {
            font-size: 0.85rem;
            color: var(--muted);
        }

        .cart-item-mini .price {
            font-weight: 500;
        }

        /* Buttons */
        .btn {
            padding: 1.2rem 2.5rem;
            background: var(--accent);
            color: white;
            border: 2px solid var(--accent);
            border-radius: 8px;
            font-size: 0.9rem;
            font-weight: 500;
            letter-spacing: 1px;
            text-transform: uppercase;
            cursor: pointer;
            transition: all 0.4s;
        }

        .btn:hover {
            background: white;
            color: var(--accent);
        }

        .btn-secondary {
            background: white;
            color: var(--accent);
            border: 2px solid var(--border);
        }

        .btn-secondary:hover {
            border-color: var(--accent);
        }

        /* Right Column - Summary */
        .checkout-summary {
            position: sticky;
            top: 120px;
            background: var(--bg-subtle);
            padding: 2.5rem;
            border-radius: 12px;
        }

        .summary-title {
            font-size: 1.3rem;
            font-weight: 500;
            margin-bottom: 2rem;
            letter-spacing: 0.3px;
        }

        .summary-items {
            margin-bottom: 2rem;
            padding-bottom: 1.5rem;
            border-bottom: 1px solid var(--border);
        }

        .summary-item {
            display: flex;
            justify-content: space-between;
            margin-bottom: 1rem;
            font-size: 0.95rem;
        }

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

        .summary-row.total {
            font-size: 1.8rem;
            font-weight: 500;
            color: var(--text);
            margin-top: 1.5rem;
            padding-top: 1.5rem;
            border-top: 1px solid var(--border);
        }

        /* Student discount row styling */
        #studentDiscount {
            display: flex !important;
            justify-content: space-between;
            margin-bottom: 0.75rem;
            color: #2e7d32;
            font-weight: 500;
            font-size: 0.95rem;
        }

        #studentDiscount.hidden {
            display: none !important;
        }

        .student-badge {
            display: inline-block;
            padding: 0.4rem 1rem;
            background: var(--success);
            color: white;
            border-radius: 20px;
            font-size: 0.8rem;
            font-weight: 500;
            margin-top: 1rem;
        }

        /* Stripe Card Element */
        .card-element {
            padding: 1rem;
            border: 1px solid var(--border);
            border-radius: 8px;
            background: white;
        }

        /* Success Modal */
        .modal-overlay {
            position: fixed;
            inset: 0;
            background: rgba(0, 0, 0, 0.5);
            display: none;
            align-items: center;
            justify-content: center;
            z-index: 9999;
        }

        .modal-overlay.show {
            display: flex;
        }

        .modal {
            background: white;
            padding: 3rem;
            border-radius: 12px;
            max-width: 500px;
            text-align: center;
        }

        .modal h2 {
            font-size: 2rem;
            font-weight: 500;
            margin-bottom: 1rem;
        }

        .modal p {
            color: var(--muted);
            margin-bottom: 2rem;
        }

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

            .checkout-summary {
                position: static;
            }
        }

        @media (max-width: 768px) {
            .progress-steps {
                flex-direction: column;
                gap: 0.5rem;
            }

            .step-arrow {
                display: none;
            }

            .field-row {
                grid-template-columns: 1fr;
            }
        }

        /* Extra small: tighten paddings and make actions full-width */
        @media (max-width: 480px) {
            .checkout-container { padding: 1.5rem; }
            .section { padding: 1rem; border-radius: 10px; }
            .btn { width: 100%; padding: 0.9rem; }
            .field input, .field textarea { padding: 0.85rem; }
            .cart-item-mini { padding: 0.75rem; gap: 0.6rem; }
            .cart-item-mini img { width: 48px; height: 48px; }
            .summary-title { font-size: 1.1rem; }
            .summary-row.total { font-size: 1.35rem; }
            .modal { padding: 2rem; margin: 1rem; max-width: calc(100% - 2rem); }
        }