Hi,
Instead of the css you've used , please try this
.post-entry-portfolio-first strong, .entry-content strong {
color: #999;
}
The reason your css didn't work on the other page is because the structure is very different on the other page, and has selectors with different names. If you want to see yourself easily:
For making customization to your theme's CSS, we recommend that you install and get to know Firebug ( http://getfirebug.com/css ) and Google Chrome developer tools ( https://developers.google.com/chrome-developer-tools/docs/overview ) browser add-on. Firebug is a free web development tool that integrates into Firefox and Chrome browsers and assists in monitoring, debugging and editing of any website's CSS, HTML, DOM, and JavaScript files.
Once installed, this easy to follow video will show you the basics of Firebug – http://vimeo.com/20917974 and get you on your way to customizing your theme like a real pro. It's 5 minutes long, and by the end you will know how to style anything!
Thanks,
Nick