If you do not want your link text to be affected, you must modify the rule for the .container selector to look like this:
.container { width: 100%; height: 90px; margin: 0 auto; background-color: rgba(255,255,255,0.5); }
It will keep your background color without affecting your text. Opacity, as stated here several times, affects the element and its children.
Use opacity. Text affected

Using rgba (255,255,255,0,5), children were not hurt

Take care of other rules that may take action due to your javascript and hover feed situations here Bis spater
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