When doing WordPress theme development I find it helpful to overlay an image of the approved design on top of the code I’m working on. I use a reduced opacity on the image so I can see the code I’m working on. This helps me match things like font size and spacing.
You can find the code at https://github.com/salcode/development-overlay.
e.g. https://example.test?src=another-image.jpg https://example.test?src=another-image.jpg&left=-20