*{box-sizing:border-box;margin:0}body{background:#fff}.container{background:#303030;height:650px;width:500px;margin:auto;margin-top:50px;border-radius:30px;padding:50px 30px}.display{width:100%;height:100px;background:#969696;border:none;border-bottom:solid 5px #000;padding:20px;font-size:40px;text-align:right}.display::-moz-placeholder{color:#000}.display:-ms-input-placeholder{color:#000}.display::placeholder{color:#000}.buttons{display:inline-grid;grid-template-columns:80px 80px 80px 150px;grid-gap:20px 16px;padding-top:20px}input[type=button]{font-family:Arial,Helvetica,sans-serif;color:#000;background:#fff;border:none;outline:none;font-size:30px;padding:20px;border-radius:20px;cursor:pointer}input[type=button]:first-child{background:red;color:#fff}input[type=button]:nth-child(2){background-color:#ffc96e}input[type=button]:nth-child(16){grid-row:4;grid-row-end:6;grid-column:4;background-color:#9380ff;color:#fff;font-size:50px}input[type=button]:nth-child(16):hover{background-color:#3d3377;transition:background .5s}.sample{color:#fff}