.card {
            perspective: 1000px;
            transform-style: preserve-3d;
            transition: transform 0.6s;
            aspect-ratio: 1 / 1;
        }
        .card.flipped {
            transform: rotateY(180deg);
        }
        .card-face {
            position: absolute;
            width: 100%;
            height: 100%;
            backface-visibility: hidden;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 2rem;
            border-radius: 0.5rem;
        }
        .card-back {
            transform: rotateY(180deg);
        }
        .custom-select {
            appearance: none;
            background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='white' viewBox='0 0 24 24'%3E%3Cpath d='M7 10l5 5 5-5z'/%3E%3C/svg%3E");
            background-repeat: no-repeat;
            background-position: right 0.5rem center;
            background-size: 1.5em;
        }
        @media (max-width: 640px) {
            .card-face {
                font-size: 1.5rem;
            }
        }
        
        .copy-alert {
            position: fixed;
            top: 20px;
            right: 20px;
            padding: 1rem 1.5rem;
            border-radius: 8px;
            background: #ff4757;
            color: white;
            font-weight: 500;
            box-shadow: 0 4px 15px rgba(255, 71, 87, 0.3);
            display: flex;
            align-items: center;
            gap: 10px;
            transform: translateX(150%);
            transition: transform 0.3s ease-in-out;
            z-index: 1000;
        }

        .copy-alert.show {
            transform: translateX(0);
        }

        .copy-alert i {
            font-size: 1.25rem;
        }

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

        .copy-alert i {
            animation: shake 0.5s ease-in-out;
        }
        
        .highlight-effect {
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: rgba(255, 71, 87, 0.1);
            opacity: 0;
            transition: opacity 0.3s ease;
        }

        .highlight-effect.active {
            opacity: 1;
        }