* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
        }

        body {
            min-height: 100vh;
            background: #f5f7fa;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 16px;
        }

        .payment-panel {
            width: 100%;
            max-width: 520px;
            background: white;
            border-radius: 24px;
            box-shadow: 0 25px 50px -12px rgba(0,0,0,0.15);
            overflow: hidden;
        }

        /* header */
        .panel-header {
            padding: 20px 20px 16px 20px;
            border-bottom: 1px solid #edf2f7;
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 12px;
        }

        .panel-header h2 {
            font-size: 20px;
            font-weight: 600;
            color: #1e293b;
            letter-spacing: -0.01em;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .panel-header h2 i {
            color: #2563eb;
            font-size: 20px;
        }

        .header-actions {
            display: flex;
            align-items: center;
            gap: 10px;
            flex-wrap: wrap;
        }

        /* amount badge */
        .amount-badge {
            background: #f1f5f9;
            padding: 6px 14px;
            border-radius: 40px;
            font-size: 15px;
            font-weight: 600;
            color: #0f172a;
            display: flex;
            align-items: center;
            gap: 6px;
            white-space: nowrap;
        }

        .amount-badge i {
            color: #2563eb;
            font-size: 14px;
        }

        /* language dropdown */
        .lang-dropdown {
            position: relative;
        }

        .lang-selector-btn {
            background: #f1f5f9;
            border: none;
            padding: 6px 12px 6px 10px;
            border-radius: 40px;
            font-size: 14px;
            font-weight: 500;
            color: #1e293b;
            display: flex;
            align-items: center;
            gap: 6px;
            cursor: pointer;
            transition: background 0.2s;
            border: 1px solid transparent;
            white-space: nowrap;
        }

        .lang-selector-btn:hover {
            background: #e2e8f0;
        }

        .lang-selector-btn .svg-icon {
            width: 18px;
            height: 18px;
        }

        .lang-menu {
            position: absolute;
            top: calc(100% + 8px);
            right: 0;
            background: white;
            border-radius: 16px;
            box-shadow: 0 20px 35px -8px rgba(0,0,0,0.2);
            min-width: 160px;
            padding: 6px;
            z-index: 50;
            display: none;
            border: 1px solid #f0f2f5;
        }

        .lang-menu.show {
            display: block;
        }

        .lang-option {
            padding: 10px 14px;
            font-size: 14px;
            color: #334155;
            border-radius: 12px;
            display: flex;
            align-items: center;
            gap: 10px;
            cursor: pointer;
            transition: background 0.15s;
        }

        .lang-option:hover {
            background: #f8fafc;
        }

        .lang-option .svg-icon {
            width: 18px;
            height: 18px;
        }

        .lang-option.selected {
            background: #eef2ff;
            color: #2563eb;
            font-weight: 500;
        }

        /* transaction details card */
        .transaction-card {
            background: #f8fafc;
            margin: 16px 20px 20px 20px;
            padding: 14px 18px;
            border-radius: 18px;
            border: 1px solid #e9eef2;
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 12px;
        }

        .transaction-info {
            display: flex;
            align-items: center;
            gap: 16px;
            flex-wrap: wrap;
        }

        .transaction-item {
            display: flex;
            align-items: center;
            gap: 8px;
            flex-wrap: wrap;
        }

        .transaction-item .label {
            font-size: 13px;
            color: #64748b;
            display: flex;
            align-items: center;
            gap: 4px;
        }

        .transaction-item .value {
            font-size: 14px;
            font-weight: 600;
            color: #0f172a;
            background: white;
            padding: 4px 12px;
            border-radius: 30px;
            border: 1px solid #e2e8f0;
            word-break: break-word;
        }

        .transaction-item .value.id {
            font-family: 'SF Mono', monospace;
            letter-spacing: 0.3px;
        }

        .copy-btn {
            background: none;
            border: none;
            color: #94a3b8;
            cursor: pointer;
            padding: 6px;
            border-radius: 8px;
            transition: all 0.2s;
        }

        .copy-btn:hover {
            background: #e2e8f0;
            color: #2563eb;
        }

        /* card preview */
        .card-mini-preview {
            background: #0f172a;
            border-radius: 16px;
            margin: 0 20px 20px 20px;
            padding: 16px 18px;
            color: white;
            display: flex;
            align-items: center;
            justify-content: space-between;
            border: 1px solid #334155;
            gap: 10px;
        }

        .preview-left {
            display: flex;
            flex-direction: column;
            gap: 8px;
            flex: 1;
            min-width: 0;
        }

        .preview-number {
            font-family: 'SF Mono', 'Menlo', monospace;
            font-size: clamp(13px, 4vw, 15px);
            letter-spacing: 1px;
            color: #e2e8f0;
            word-break: break-word;
        }

        .preview-details {
            display: flex;
            gap: 16px;
            font-size: 11px;
            color: #94a3b8;
            text-transform: uppercase;
            flex-wrap: wrap;
        }

        .preview-details span {
            color: #f1f5f9;
            font-weight: 500;
            margin-left: 4px;
        }

        .card-type-icon i {
            font-size: 28px;
            color: #e2e8f0;
            opacity: 0.7;
        }

        /* form */
        .payment-form {
            padding: 0 20px 24px 20px;
        }

        .input-row {
            margin-bottom: 18px;
        }

        .input-label {
            display: flex;
            align-items: center;
            gap: 6px;
            font-size: 13px;
            font-weight: 500;
            color: #475569;
            margin-bottom: 6px;
        }

        .input-label i {
            color: #64748b;
            width: 16px;
            font-size: 14px;
        }

        .field-wrapper {
            position: relative;
        }

        .field-wrapper i.input-icon {
            position: absolute;
            left: 14px;
            top: 50%;
            transform: translateY(-50%);
            color: #94a3b8;
            font-size: 15px;
            pointer-events: none;
        }

        .field-wrapper input {
            width: 100%;
            padding: 14px 16px 14px 44px;
            border: 1px solid #e2e8f0;
            border-radius: 14px;
            font-size: 15px;
            background: #ffffff;
            transition: all 0.15s;
            color: #0f172a;
            -webkit-appearance: none;
        }

        .field-wrapper input:focus {
            outline: none;
            border-color: #2563eb;
            box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
        }

        .field-wrapper input::placeholder {
            color: #a0afbe;
            font-weight: 400;
            font-size: 14px;
        }

        .row-fields {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 12px;
            margin-bottom: 8px;
        }

        .cvv-wrapper {
            position: relative;
        }

        .cvv-wrapper input {
            padding-right: 45px;
        }

        .cvv-toggle {
            position: absolute;
            right: 12px;
            top: 50%;
            transform: translateY(-50%);
            background: none;
            border: none;
            color: #94a3b8;
            cursor: pointer;
            font-size: 16px;
            padding: 6px;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        .cvv-toggle:hover {
            color: #475569;
        }

        .error-message {
            font-size: 12px;
            color: #dc2626;
            margin-top: 5px;
            min-height: 18px;
            display: flex;
            align-items: center;
            gap: 4px;
        }

        /* billing section */
        .billing-section {
            margin: 0 0 20px 0;
            background: #ffffff;
        }

        .billing-title {
            font-size: 15px;
            font-weight: 600;
            color: #1e293b;
            margin-bottom: 16px;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .billing-title i {
            color: #2563eb;
            font-size: 16px;
        }

        .billing-grid {
            display: flex;
            flex-direction: column;
            gap: 16px;
        }

        .billing-row {
            display: flex;
            flex-direction: column;
            gap: 6px;
        }

        .billing-label {
            font-size: 13px;
            font-weight: 500;
            color: #475569;
            display: flex;
            align-items: center;
            gap: 6px;
        }

        .billing-label i {
            color: #64748b;
            width: 16px;
            font-size: 14px;
        }

        .billing-field {
            position: relative;
        }

        .billing-field i {
            position: absolute;
            left: 14px;
            top: 50%;
            transform: translateY(-50%);
            color: #94a3b8;
            font-size: 15px;
            pointer-events: none;
        }

        .billing-field input,
        .billing-field select {
            width: 100%;
            padding: 12px 16px 12px 44px;
            border: 1px solid #e2e8f0;
            border-radius: 14px;
            font-size: 15px;
            background: #ffffff;
            transition: all 0.15s;
            color: #0f172a;
            -webkit-appearance: none;
        }

        .billing-field select {
            cursor: pointer;
            background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
            background-repeat: no-repeat;
            background-position: right 14px center;
            padding-right: 40px;
        }

        .billing-field input:focus,
        .billing-field select:focus {
            outline: none;
            border-color: #2563eb;
            box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
        }

        .billing-field input::placeholder {
            color: #a0afbe;
            font-size: 14px;
        }

        .address-row {
            display: grid;
            grid-template-columns: 2fr 1fr;
            gap: 12px;
        }

        .pay-button {
            width: 100%;
            background: #0f172a;
            border: none;
            border-radius: 16px;
            padding: 16px;
            color: white;
            font-weight: 600;
            font-size: 16px;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            cursor: pointer;
            transition: background 0.2s;
            margin-top: 16px;
            border: 1px solid #1e293b;
            -webkit-tap-highlight-color: transparent;
        }

        .pay-button:hover {
            background: #1e293b;
        }

        .pay-button:active {
            transform: scale(0.98);
        }

        .pay-button i {
            font-size: 16px;
            color: #a5b4fc;
        }

        .secure-note {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            margin-top: 14px;
            color: #64748b;
            font-size: 12px;
            flex-wrap: wrap;
            text-align: center;
        }

        hr {
            border: none;
            border-top: 1px solid #edf2f7;
            margin: 16px 0 18px;
        }

        @media (max-width: 480px) {
            .address-row {
                grid-template-columns: 1fr;
                gap: 16px;
            }
            
            .billing-section {
                padding: 16px;
            }
        }

        @media (max-width: 380px) {
            .panel-header {
                flex-direction: column;
                align-items: flex-start;
            }
            
            .header-actions {
                width: 100%;
                justify-content: space-between;
            }
            
            .transaction-info {
                flex-direction: column;
                align-items: flex-start;
                gap: 8px;
            }
            
            .row-fields {
                grid-template-columns: 1fr;
                gap: 16px;
            }
            
            .card-mini-preview {
                flex-direction: column;
                align-items: flex-start;
            }
            
            .card-type-icon {
                align-self: flex-end;
            }
        }