html-css-review: Add `alt` to completion `<img>` for accessibility
html-css-review: Switch from `em`/`strong` elements to classes

LMS base styles can't be relied upon to provide the generally related styles, bolded and italicized text respectively, for these elements
html-css-review: Avoid styling with HTML elements as selectors
html-css-review: Consistently use pixels, do not mix relative sizes