:root {
            color-scheme: light;
            --navy: #111827;
            --blue: #3B82F6;
            --blue-hover: #2563EB;
            --green: #10B981;
            --white: #FFFFFF;
            --surface: #F9FAFB;
            --border: #E5E7EB;
            --border-strong: #D1D5DB;
            --muted: #6B7280;
            --text: #111827;
            --error: #DC2626;
        }

        * {
            box-sizing: border-box;
        }

        body {
            margin: 0;
            background: var(--surface);
            color: var(--text);
            font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
            -webkit-font-smoothing: antialiased;
        }

        a {
            color: var(--blue);
            text-underline-offset: 3px;
        }

        a:hover {
            text-decoration-thickness: 2px;
        }

        .checkout-header {
            width: 100%;
            background: var(--navy);
        }

        .checkout-header__inner {
            width: min(100% - 48px, 1180px);
            min-height: 76px;
            margin: 0 auto;
            display: flex;
            align-items: center;
            justify-content: space-between;
            gap: 24px;
        }

        .checkout-header__logo {
            display: inline-flex;
            align-items: center;
        }

        .checkout-header__logo img {
            display: block;
            width: auto;
            height: 36px;
        }

        .checkout-shell {
            width: min(100% - 48px, 1180px);
            margin: 0 auto;
            padding: 72px 0 96px;
            display: grid;
            grid-template-columns: minmax(0, 1fr) minmax(340px, 420px);
            gap: clamp(48px, 7vw, 88px);
            align-items: start;
        }

        .access-panel {
            max-width: 640px;
            padding-top: 8px;
        }

        .access-panel h1 {
            max-width: 620px;
            margin: 0;
            color: var(--text);
            font-size: clamp(2.25rem, 4.2vw, 3.65rem);
            font-weight: 750;
            letter-spacing: -0.045em;
            line-height: 1.08;
        }

        .access-intro {
            max-width: 610px;
            margin: 26px 0 0;
            color: var(--muted);
            font-size: 1.1rem;
            line-height: 1.65;
        }

        .account-prompt {
            margin: 32px 0 0;
            color: #4B5563;
            font-size: 0.95rem;
        }

        .checkout-form {
            max-width: 610px;
            margin-top: 44px;
        }

        .field-label {
            display: block;
            margin-bottom: 10px;
            font-size: 1rem;
            font-weight: 700;
        }

        .email-input {
            width: 100%;
            min-height: 58px;
            padding: 0 16px;
            border: 1px solid var(--border-strong);
            border-radius: 8px;
            background: var(--white);
            color: var(--text);
            font: inherit;
            font-size: 1rem;
            outline: none;
            transition: border-color 0.15s ease, box-shadow 0.15s ease;
        }

        .email-input::placeholder {
            color: #9CA3AF;
        }

        .email-input:hover {
            border-color: #9CA3AF;
        }

        .email-input:focus-visible {
            border-color: var(--blue);
            box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
        }

        .field-note,
        .email-error {
            margin: 10px 0 0;
            font-size: 0.9rem;
            line-height: 1.5;
        }

        .field-note {
            color: var(--muted);
        }

        .email-error {
            display: none;
            color: var(--error);
            font-weight: 600;
        }

        .signed-in-account {
            padding: 16px 0;
            border-top: 1px solid var(--border);
            border-bottom: 1px solid var(--border);
        }

        .signed-in-account__label {
            display: block;
            margin-bottom: 4px;
            color: var(--muted);
            font-size: 0.8rem;
            font-weight: 700;
            letter-spacing: 0.06em;
            text-transform: uppercase;
        }

        .signed-in-account__email {
            font-weight: 700;
            overflow-wrap: anywhere;
        }

        .signed-in-account__switch {
            display: inline-block;
            margin-top: 10px;
            font-size: 0.9rem;
        }

        .terms {
            margin: 36px 0 0;
            display: grid;
            grid-template-columns: 20px minmax(0, 1fr);
            gap: 10px;
            align-items: start;
            color: #4B5563;
            font-size: 0.92rem;
            line-height: 1.5;
        }

        .terms input {
            width: 18px;
            height: 18px;
            margin: 2px 0 0;
            accent-color: var(--blue);
        }

        .checkout-button {
            width: 100%;
            min-height: 58px;
            margin-top: 28px;
            border: 0;
            border-radius: 8px;
            background: var(--blue);
            color: var(--white);
            cursor: pointer;
            font: inherit;
            font-size: 1.05rem;
            font-weight: 750;
            transition: background-color 0.15s ease, transform 0.15s ease;
        }

        .checkout-button:hover {
            background: var(--blue-hover);
        }

        .checkout-button:active {
            transform: translateY(1px);
        }

        .checkout-button:focus-visible,
        .coupon-button:focus-visible,
        .coupon-summary:focus-visible {
            outline: 3px solid rgba(59, 130, 246, 0.3);
            outline-offset: 3px;
        }

        .payment-note {
            margin: 22px 0 0;
            padding-top: 22px;
            border-top: 1px solid var(--border);
            color: var(--muted);
            font-size: 0.9rem;
            text-align: center;
        }

        .order-summary {
            position: sticky;
            top: 24px;
            padding: 26px;
            border: 1px solid var(--border);
            border-radius: 14px;
            background: var(--white);
            box-shadow: 0 12px 32px rgba(17, 24, 39, 0.06);
        }

        .order-summary h2 {
            margin: 0 0 20px;
            font-size: 1.35rem;
            letter-spacing: -0.02em;
        }

        .product-cover {
            display: block;
            width: 100%;
            aspect-ratio: 4 / 3;
            border-radius: 10px;
            background: var(--navy);
            object-fit: contain;
            object-position: center;
        }

        .product-title {
            margin: 20px 0 0;
            font-size: 1.08rem;
            font-weight: 750;
            line-height: 1.35;
        }

        .purchase-type {
            margin: 5px 0 0;
            color: var(--muted);
            font-size: 0.92rem;
        }

        .price-breakdown {
            margin-top: 22px;
            padding-top: 18px;
            border-top: 1px solid var(--border);
        }

        .price-row {
            display: flex;
            justify-content: space-between;
            gap: 24px;
            padding: 8px 0;
            color: #4B5563;
            font-size: 0.95rem;
        }

        .price-row span:last-child {
            color: var(--text);
            font-variant-numeric: tabular-nums;
        }

        .price-row--discount span:last-child {
            color: var(--green);
            font-weight: 700;
        }

        .price-row--total {
            margin-top: 8px;
            padding-top: 16px;
            border-top: 1px solid var(--border);
            color: var(--text);
            font-size: 1.05rem;
            font-weight: 750;
        }

        .tax-note {
            margin: 2px 0 0;
            color: var(--muted);
            font-size: 0.78rem;
        }

        .coupon-details {
            margin-top: 22px;
            padding-top: 20px;
            border-top: 1px dashed var(--border);
        }

        .coupon-summary {
            color: var(--blue);
            cursor: pointer;
            font-size: 0.92rem;
            font-weight: 650;
            list-style: none;
        }

        .coupon-summary::-webkit-details-marker {
            display: none;
        }

        .coupon-summary::after {
            content: "+";
            margin-left: 7px;
            color: var(--muted);
        }

        .coupon-details[open] .coupon-summary::after {
            content: "−";
        }

        .coupon-form {
            margin-top: 14px;
            display: grid;
            grid-template-columns: minmax(0, 1fr) auto;
            gap: 8px;
        }

        .coupon-input {
            min-width: 0;
            min-height: 44px;
            padding: 0 12px;
            border: 1px solid var(--border-strong);
            border-radius: 7px;
            color: var(--text);
            font: inherit;
            font-size: 0.9rem;
            outline: none;
        }

        .coupon-input:focus-visible {
            border-color: var(--blue);
            box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.16);
        }

        .coupon-button {
            min-height: 44px;
            padding: 0 14px;
            border: 1px solid var(--border-strong);
            border-radius: 7px;
            background: var(--surface);
            color: var(--text);
            cursor: pointer;
            font: inherit;
            font-size: 0.88rem;
            font-weight: 700;
        }

        .coupon-button:hover {
            background: var(--border);
        }

        .coupon-error {
            grid-column: 1 / -1;
            margin: 0;
            color: var(--error);
            font-size: 0.85rem;
            font-weight: 600;
        }

        @media (max-width: 900px) {
            .checkout-shell {
                grid-template-columns: 1fr;
                gap: 48px;
                padding-top: 48px;
            }

            .access-panel,
            .checkout-form {
                max-width: none;
            }

            .order-summary {
                position: static;
            }
        }

        @media (max-width: 600px) {
            .checkout-header__inner,
            .checkout-shell {
                width: min(100% - 32px, 1180px);
            }

            .checkout-header__inner {
                min-height: 68px;
            }

            .checkout-header__logo img {
                height: 30px;
            }

            .checkout-shell {
                padding: 40px 0 64px;
                gap: 40px;
            }

            .access-panel h1 {
                font-size: 2.25rem;
            }

            .access-intro {
                margin-top: 20px;
                font-size: 1rem;
            }

            .account-prompt {
                margin-top: 26px;
            }

            .checkout-form {
                margin-top: 34px;
            }

            .terms {
                margin-top: 30px;
            }

            .order-summary {
                padding: 20px;
                border-radius: 12px;
            }

            .coupon-form {
                grid-template-columns: 1fr;
            }
        }

        @media (prefers-reduced-motion: reduce) {
            *,
            *::before,
            *::after {
                scroll-behavior: auto !important;
                transition: none !important;
            }
        }