Bug: yellow color previous to adsense load

There is a line in style.css that makes yellow the Adsense space previous to ad load.
.entry ins { background: #fff486; }
I don’t now if this line has to be there, but that happens to be in this theme, and other themes, and other cms.

I put in child theme:
.entry ins { background: none; }

That works, but as I am complete ignorant in writing code lines, if some body knows a better way, I’ll be glad to learn.