Lint all plain CSS, match coding style and be lint-free

Carry out tests in base theme

1. Go to the Site administration > Plugins > Blocks > Course overview
2. Enable the welcome area
3. Go to your dashboard
4. VERIFY: the 'Welcome <name>' area looks the same alignment before and after the patch

1. Add a database activity to a course
2. 'choose a predefined set to get started.'
3. Select 'image gallery' from use a preset
4. VERIFY: looks the same before and after the patch

1. Add a wiki activity
2. Create a page and add a heading to that page
3. When the page is saved, there should be an [edit] link next to the heading
4. VERIFY: the edit link looks the same before and after the patch

1. Go to course page with blocks
2. VERIFY: the top right +/- icons are aligned the same before and after the patch

1. Message someone
2. Go to your messaging history with that user
3. VERIFY: the user icons in the history look the same before and after the patch

1. Enable mod_assign with file uploads and editpdf/unconv
2. Assign a pdf as a student
3. Go to grade the assignment
4. Press the hide pane buttons on the bottom right of the sceren
5. VERIFY: the animation transitions are smooth and better or the same as before