I am guessing that the colour of the text is being overwritten somewhere else in your stylesheet.
Try being more specific with your rule, such as #container input.my-textBox { ... }
Also, try putting the rule at the very end of your stylesheet and make sure that the stylesheet it's in is the very last stylesheet that's loaded when the browser loads the page.
Finally, make sure there's no inline CSS on the input element itself that's overriding your color
rule.