How to override A tag CSS in base.css

Hi, Need to meet WCAG 2.0 AA accessibility requirements.

I have accessibility issues created by the CSS at:
enfold/css/base.css?ver=2 line 120, line 121

a { text-decoration: none; outline: 0; max-width:100%; max-width:none\9; }
a:hover, a:focus, a:visited { outline: 0; text-decoration: underline;}

Accessibility scans say that text-decoration: none; and outline: 0; are accessibility offenses.

“Removing the underline from links makes it hard for color-blind users to see them.
Remove the text-decoration:none property from your link styles, or add other non-color style attributes to visually distinguish links.”
https://www.w3.org/TR/WCAG20-TECHS/F73.html

“This CSS style makes it difficult or impossible to see the dotted link focus outline.
Change the style to avoid obscuring the focus outline around A elements, which is used when tabbing through links.”
https://www.w3.org/TR/WCAG20-TECHS/F78.html

Is there a way to override these CSS settings in the CHILD THEME so that we don’t have maintain this in Enfold every time we update?

I tried putting this in QUICK CSS:

a { 
    text-decoration: underline; 
}
a:hover, a:focus { outline: #0099cc solid thin; }

This did not satisfy the accessibility scan. Any ideas?