使用filter方式将图片设置为灰色
普通图片使用：
filter: saturate(0);纯白图片使用：
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
img {
width: 100px;
height: 100px;
}
.box1 .img2 {
filter: saturate(0);
}
.box2 .img4 {
filter: brightness(0.6);
}
</style>
</head>
<body>
<div class="box1">
<img class="img1" src="./img/图标-放大.svg" alt="">
<img class="img2" src="./img/图标-放大.svg" alt="">
</div>
<!-- 纯白 -->
<div class="box2">
<img class="img3" src="./img/图标-缩小.svg" alt="">
<img class="img4" src="./img/图标-缩小.svg" alt="">
</div>
</html>