3 {
            from { transform: scale(1) rotate(0deg); }
            to { transform: scale(1.5) rotate(90deg); }
        }

        /* ------------------- */
        /* --- Header & Theme Toggle --- */
        /* ------------------- */
        .header {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            padding: 1rem 2rem;
            display: flex;
            justify-content: space-between;
            align-items: center;
        