Three distinct rules are required, one for each circumstance. Choose the range, then use a formula to generate new rules. The formulas I used in this example are visible. Keep in mind that the formula must utilize the first cell in the selection as a reference and should not contain any $ signs, so use C2 rather than $c$2. C2 is the initial cell in the selection in my example, and my rules are:
Take a look at the screenshot to see how the rules must be set up such that cells with less than 50% of the yellow colour are not affected. For added assurance that no additional rules are enforced, you might optionally check the "Stop if true" box.