1. 横幅
hover me
2. properties
hover me
transition-property: width;
transition-duration: 2s;
transition-timing-function: linear;
transition-delay: 1s;
3. 横幅+縦幅 2秒、縦幅1秒
hover me
4. timing
hover me
linear 2s
hover me
ease 2s
hover me
ease-in 2s
hover me
ease-out 2s
hover me
ease-in-out 2s