css html 渐变按钮

 .btn{background:-webkit-linear-gradient(left, #FF0000 0%, #4d4c4c 0%, #252220 100%);background:linear-gradient(90deg, #FF0000 0%, #FF0000 0%, #FF0000 100%);border-radius:1rem;width:100%;height:2.88rem;display:-webkit-box;display:-ms-flexbox;display:flex;-webkit-box-pack:center;-ms-flex-pack:center;justify-content:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;color:#FFFFFF;font-size:16px;font-weight:500}

      <a href="#" >
	               <div class="btn">购买</div>
	             </a>
	             

效果