It turns out that for a long time do not do, will forget ah, ah, ah, ah ~
1, merge layers
The combined plurality of layers CTRL + E
2, sliced
3, Export
------ ------- exported file storage format used for web -------- >>>>>>>>>>>>>>>> obtain images folder
4, get css styles for each button is located
Button to get a new layer with the rectangle tool, after all the buttons are new layers into the group, css replication group
5, px turn vw
New less file, copied into all css styles, replace: px ----> / 7.5vw (this is the original width of 7.5 pixels, 720 pixels as compared to 7.2)
6, get the picture size value in ps
Image --------> Image size
