Why I set up the item2, right, and bottom and item2 width is high, it can stretch upwards, rather than stretching down based on the right, and bottom?
<meta charset="utf-8" & gt;
<meta name="viewport" content="width=device - width" & gt;
JS Bin
<style>
The box {
position: relative;
width: 300px;
Height: 100 px;
Border: 10 px solid red;
box-sizing: border-box;
}
The item2 {
position: absolute;
right: -10px;
bottom: -10px;
Width: 0 px;
height: 0px;
box-sizing: border-box;
Border: 10 px solid transparent;
}
Box: hover. Item2 {
box-sizing: border-box;
width: 300px;
Height: 100 px;
Border - color: black.
The transition: all 1 s;
}
</style>
<body>
