.header{background:linear-gradient(135deg,#3498db,#2a5298);color:#fff;text-align:center;position:relative;overflow:hidden;height:120px;display:flex;align-items:center;justify-content:center}.header:before{content:"";position:absolute;top:-50%;left:-50%;width:200%;height:200%;background:radial-gradient(circle,hsla(0,0%,100%,.1) 0,transparent 70%);animation:float 6s ease-in-out infinite}@keyframes float{0%,to{transform:translateY(0) rotate(0deg)}50%{transform:translateY(-20px) rotate(180deg)}}