:root {
            --primary-shade: #e91e63;
            --secondary-shade: #f06292;
            --accent-color: #ff6090;
            --text-dark: #2c3e50;
            --text-light: #7f8c8d;
            --bg-light: #fef5f8;
            --border-tone: #f8bbd0;
            --success-tone: #ff4081;
        }

        html, body {
            margin: 0;
            padding: 0;
            height: 100%;
        }

        body {
            font-family: 'Arial', 'Helvetica', sans-serif;
            background: radial-gradient(circle at top right, #fce4ec, #f8bbd0, #f48fb1);
            min-height: 100vh;
            
            line-height: 1.6;
        }

        .calculator-wrapper {
            background: #ffffff;
            box-shadow: 0 20px 60px rgba(233, 30, 99, 0.15);
            border-radius: 20px;
            overflow: hidden;
            max-width: 650px;
            width: 100%;
            margin: 0 auto;
            animation: slideIn 0.5s ease-out;
        }

        @keyframes slideIn {
            from {
                opacity: 0;
                transform: translateY(30px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .calc-header {
            background: linear-gradient(120deg, var(--primary-shade), var(--secondary-shade));
            color: white;
            padding: 2.5rem 2rem;
            text-align: center;
        }

        .calc-header h1 {
            font-size: 2rem;
            margin: 0 0 0.5rem 0;
            font-weight: 700;
        }

        .calc-header p {
            margin: 0;
            opacity: 0.95;
            font-size: 1rem;
        }

        .calc-body {
            padding: 2rem;
        }

        .instruction-panel {
            background: var(--bg-light);
            border-radius: 12px;
            padding: 1.25rem;
            margin-bottom: 1.75rem;
            border-left: 5px solid var(--primary-shade);
            font-size: 0.9rem;
            color: var(--text-dark);
        }

        .instruction-panel strong {
            color: var(--primary-shade);
            display: block;
            margin-bottom: 0.5rem;
        }

        .instruction-panel ul {
            margin: 0.5rem 0 0 1.5rem;
            padding: 0;
        }

        .instruction-panel li {
            margin-bottom: 0.4rem;
        }

        .measurement-unit-selector {
            margin-bottom: 2rem;
        }

        .measurement-unit-selector label {
            display: block;
            font-weight: 700;
            color: var(--text-dark);
            margin-bottom: 1rem;
            font-size: 0.95rem;
        }

        .unit-buttons-group {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 0.75rem;
        }

        .unit-option {
            padding: 0.9rem;
            border: 2px solid var(--border-tone);
            background: white;
            border-radius: 10px;
            cursor: pointer;
            font-weight: 600;
            font-size: 0.9rem;
            color: var(--text-light);
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            text-align: center;
        }

        .unit-option:hover {
            border-color: var(--secondary-shade);
            background: var(--bg-light);
        }

        .unit-option.selected {
            background: linear-gradient(120deg, var(--primary-shade), var(--secondary-shade));
            color: white;
            border-color: var(--primary-shade);
            transform: scale(1.05);
        }

        .input-field-group {
            margin-bottom: 1.75rem;
        }

        .input-field-group label {
            display: block;
            font-weight: 700;
            color: var(--text-dark);
            margin-bottom: 0.75rem;
            font-size: 0.95rem;
        }

        .input-container {
            position: relative;
            display: flex;
            align-items: stretch;
        }

        .input-container input {
            flex: 1;
            padding: 1rem 1.25rem;
            border: 2px solid var(--border-tone);
            border-radius: 10px;
            font-size: 1rem;
            transition: all 0.3s ease;
            background: white;
            color: var(--text-dark);
        }

        .input-container input:focus {
            outline: none;
            border-color: var(--primary-shade);
            box-shadow: 0 0 0 3px rgba(233, 30, 99, 0.1);
        }

        .input-container .unit-display {
            position: absolute;
            right: 1.25rem;
            top: 50%;
            transform: translateY(-50%);
            font-weight: 600;
            color: var(--text-light);
            font-size: 0.9rem;
            pointer-events: none;
        }

        .validation-msg {
            color: #c62828;
            font-size: 0.85rem;
            margin-top: 0.5rem;
            padding: 0.6rem 0.9rem;
            background: #ffebee;
            border-radius: 6px;
            display: none;
        }

        .validation-msg.visible {
            display: block;
            animation: shake 0.3s ease;
        }

        @keyframes shake {
            0%, 100% { transform: translateX(0); }
            25% { transform: translateX(-5px); }
            75% { transform: translateX(5px); }
        }

        .action-buttons {
            display: grid;
            grid-template-columns: 2fr 1fr;
            gap: 1rem;
            margin-top: 2rem;
        }

        .calc-btn {
            padding: 1rem;
            border: none;
            border-radius: 10px;
            font-size: 1rem;
            font-weight: 700;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .calc-btn.primary {
            background: linear-gradient(120deg, var(--primary-shade), var(--secondary-shade));
            color: white;
        }

        .calc-btn.primary:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(233, 30, 99, 0.3);
        }

        .calc-btn.primary:active {
            transform: translateY(-1px);
        }

        .calc-btn.secondary {
            background: #eceff1;
            color: var(--text-dark);
            border: 2px solid #cfd8dc;
        }

        .calc-btn.secondary:hover {
            background: #cfd8dc;
        }

        .output-area {
            display: none;
            margin-top: 2rem;
            border-top: 2px dashed var(--border-tone);
            padding-top: 2rem;
        }

        .output-area.visible {
            display: block;
            animation: fadeInUp 0.5s ease;
        }

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

        .size-display-card {
            background: linear-gradient(135deg, #f50057, #ff4081, #ff6090);
            color: white;
            padding: 2rem;
            border-radius: 15px;
            text-align: center;
            margin-bottom: 1.5rem;
            box-shadow: 0 10px 30px rgba(245, 0, 87, 0.3);
        }

        .size-display-card h3 {
            font-size: 1.1rem;
            margin: 0 0 1rem 0;
            font-weight: 600;
            opacity: 0.95;
        }

        .size-display-card .final-size {
            font-size: 3rem;
            font-weight: 900;
            letter-spacing: 3px;
            text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
        }

        .measurement-summary {
            background: #fafafa;
            border-radius: 12px;
            padding: 1.5rem;
            margin-bottom: 1.5rem;
        }

        .summary-item {
            display: flex;
            justify-content: space-between;
            padding: 0.9rem 0;
            border-bottom: 1px solid #e0e0e0;
        }

        .summary-item:last-child {
            border-bottom: none;
        }

        .summary-item .label {
            color: var(--text-light);
            font-weight: 600;
            font-size: 0.9rem;
        }

        .summary-item .value {
            color: var(--text-dark);
            font-weight: 700;
            font-size: 1rem;
        }

        .international-sizes {
            margin-top: 1.5rem;
        }

        .international-sizes h4 {
            color: var(--text-dark);
            font-size: 1.1rem;
            margin-bottom: 1rem;
            font-weight: 700;
        }

        .sizes-grid {
            display: grid;
            gap: 1rem;
        }

        .size-card {
            display: flex;
            justify-content: space-between;
            align-items: center;
            background: white;
            padding: 1rem 1.25rem;
            border-radius: 10px;
            border: 2px solid var(--border-tone);
            transition: all 0.3s ease;
        }

        .size-card:hover {
            border-color: var(--primary-shade);
            box-shadow: 0 4px 12px rgba(233, 30, 99, 0.1);
            transform: translateX(5px);
        }

        .size-card .region {
            font-weight: 600;
            color: var(--text-light);
            font-size: 0.9rem;
        }

        .size-card .size-value {
            font-weight: 700;
            color: var(--text-dark);
            font-size: 1.1rem;
        }

        @media (max-width: 640px) {
            .calc-header h1 {
                font-size: 1.6rem;
            }

            .calc-body {
                padding: 1.5rem;
            }

            .action-buttons {
                grid-template-columns: 1fr;
            }

            .size-display-card .final-size {
                font-size: 2.5rem;
            }
        }