See this example - I assume the colour was #ffc7c0. Set the block colours as needed then the token+css handling to get the text colour change.
<html depends="$hidden$">
<style>
#result_viz text {
fill: $result_foreground$ !important;
}
</style>
</html>
<single id="result_viz">
<title>Value >0 colour #ffc7c0 or <=0 #c6efce</title>
<search>
<query>| makeresults
| eval value=(random() % 100) - 50
</query>
<done>
<eval token="result_foreground">if($result.value$>0, "#9c0006", "#006100")</eval>
</done>
</search>
<option name="colorMode">block</option>
<option name="drilldown">all</option>
<option name="height">60</option>
<option name="rangeColors">["0xc6efce","0xffc7c0"]</option>
<option name="rangeValues">[1]</option>
<option name="useColors">1</option>
</single>
