Specificity rules only apply if different Rules target the **same element (as for your color of the label), not if different elements are targeted (even if some styles of that element would be inherited).
You have one stylerule applied to labels, and that is the color, which gets applied correctly. All your other styles are applied to another element, so the TB styles targeting the label directly are preferred of course.
Some styles are inherited (like font-size and line-height in your example), but they are overridden as soon as there is a rule targeting your element directly. TB overrides your font-size and line-height with the following rule:
label, input, button, select, textarea {
font-size: 14px;
font-weight: normal;
line-height: 20px;
}
You could fix this easily by declaring:
div.teaser h1.teaserText label {
color: #FCCE00;
font-size:inherit;
line-height:inherit;
/* and so on */
}