body{margin:0;padding:0;background:linear-gradient(135deg,#3d3b3b,#353333,#333232);background-size:400% 400%;animation:gradientShift 15s ease infinite;min-height:100vh;color:#fff}@keyframes gradientShift{0%{background-position:0% 0%}50%{background-position:100% 100%}to{background-position:0% 0%}}h1,button,div{position:relative;z-index:10}