使用 object-fit: contain;
官方说明: https://developer.mozilla.org/zh-CN/docs/Web/CSS/object-fit
<html>
<head>
<title></title>
<meta charset="UTF-8">
</head>
<style>
.container {
border: 1px solid red;
width: 60%;
}
img {
object-fit: contain;
width: 100%;
height: 100%;
}
</style>
<body>
<div>
<div class="container"><img src="1.png" /></div>
<div class="container"><img src="2.png" /></div>
</div>
</body>
</html>
