As Andrew mentioned earlier, your rules don’t have enough specificity. If you use a web debugging tool like Firebug or Chrome Developer Tools, you’ll be able to see the rules which are in effect for a particular element and write your selectors with a high enough specificity to override them. For example, open up this page in Chrome and right-click on the link towards the bottom of the page (inside the page content) and select Inspect element. Chrome DevTools will open up in the bottom half of the browser, with the link element highlighted in the left pane and the CSS rules which are in effect for that element on the right. If you scroll down the right pane, you’ll eventually come to the rule which you wrote, and you’ll see it struck out. That’s because the rules above have a higher specificity (the CSS rules are arranged in order of specificity). You’ll see this rule at the top:
a:visited {
color: #e8d141;
}
So if you’ve already visited the link, you’ll see this yellow color instead of the green because the :visited pseudo-class adds 10 points to the specificity. If you didn’t visit the link, then this rule will have precedence:
.entry-content a,
.comment-content a {
color: #bc360a;
}
Again, the .entry-content class adds 10 points to the specificity, so it’s going to take precedence over your green rule. So, if you want to make the links green, the first thing you should do is copy the selector from the second rule above (by adding the .entry-content class) into your own rule, so it looks like this:
.entry-content a {
color: #459c8e;
text-decoration: none;
}
As long as your rule comes after the existing rule with the same selector (or specificity), then your rule will take precedence.