.container{max-width:240px;display:block;margin-inline:auto;border:1px solid #000}button{border:none;width:54px;height:54px;text-align:center;text-decoration:none;display:inline-block;font-size:20px;cursor:pointer;margin:0}button.number{background-color:#485461;color:#fff}button.operator{background-color:#4357692d;color:#000}button.special{background-color:#f33d1d;color:#fff}button:hover,button:active{opacity:.8}#value{width:100%;height:54px;font-size:36px;background-color:#fff;color:#000;text-align:right}#result{width:100%;height:36px;font-size:24px;background-color:#fff;color:#3f3f3f;text-align:right}*{margin:0;padding:0;box-sizing:border-box}body{background-color:#f5f5f5;font-family:Roboto,sans-serif;height:100vh;width:100vw;display:grid;place-items:center}