Inline Element Changes Parent Size
The height of parent elements can change when an inline-level element has the default value for vertical-align, which is baseline. This is because baseline may result in the browser adding extra space above and below the element to align the baselines of the inline-level element and its parent element, which can cause the parent to be larger than expected. 1
Changing vertical-align from the default value of baseline to top or bottom both fix the issue. 1