How to fix header css issues after log in to wordpress.

Step 1: Go to wp-content/plugins folder.

Step 2: Rename the plugins folder to anything you want .let say plugin1.

Step 3: Refresh your wp-admin dashboard page.

Step 5: press Ctrl F5.

Step 6: CSS issues will almost gone away now.

Step 7: Now Rename your plugins folder as it was.

Step 8: If renaming plugins doesn't work try renaming themes.it will work.