<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
input {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
text-transform: uppercase;
width: 200px;
height: 40px;
border: 1px solid #000;
background: -webkit-linear-gradient(90deg, #fff, #fff, #000, #000);
background: -moz-linear-gradient(90deg, #fff, #fff, #000, #000);
background: -o-linear-gradient(90deg, #fff, #fff, #000, #000);
background: linear-gradient(90deg, #fff, #fff, #000, #000);
background-size: 300% 300%;
background-position: 1% 50%;
transition: all 1s ease;
-webkit-transition: background 0.3s ease;
-moz-transition: background 0.3s ease;
-o-transition: background 0.3s ease;
outline: none;
cursor: pointer;
}
input:hover {
color: #fff;
background-position: 99% 50%;
}
</style>
</head>
<body>
<input type="button" value="button">
</body>
</html>
这个是利用background-position属性的变化实现的渐变效果
还可以通过box-shadow属性来实现这种动画效果，只是颜色不会有一个平滑的过度
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
}
body {
font: 14px/1.5 Arial;
box-sizing: border-box;
}
.btn {
display: block;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
text-transform: uppercase;
width: 200px;
height: 40px;
text-decoration: none;
color: #fff;
text-align: center;
line-height: 40px;
border: 1px solid #d91222;
-moz-box-shadow: 200px 0 #d91222 inset; /*通过正负值调整变化方向*/
box-shadow: 200px 0 #d91222 inset;
-webkit-transition: all 0.3s;
-moz-transition: all 0.3s;
-o-transition: all 0.3s;
transition: all 0.3s;
}
.btn:hover {
box-shadow: 0 0 #d91222 inset;
color: #d91222;
}
</style>
</head>
<body>
<div><a href="javascript:void(0)" class="btn">Hover me</a></div>
</body>
</html>