I experienced a very annoying thing revently. My GMail looked like the top elements (buttons colors etc.) was scrambled together like the CSS was wrong or something. On my other computers and my phone and iPad i had no problems. It turns out that it detected the page as to be shown in "Compact View". Now i changed it to be shown in standard view. Here is how to solve it if you run into this problem:

1. Open the Gmail page

2. Press F12 to access the developer tools

3. Go to the menu "Browser Mode"

4. Change this to IE9 (the one i was using)

Now you are all done and GMail should again look like it should. Hope you find this helpful