The text should be default:
<isindex value="default">
The text should be red:
<isindex style="color:red" value="red">
The text should be gray on green:
<isindex style="background-color:green" value="default on green">
The text should be red on Green:
<isindex style="color:red;background-color:green" value="red on green">

<input type=text value="default">
<input type=text style="color:red" value="red">
<input type=text style="background-color:green" value="default on green">
<input type=text style="color:red;background-color:green" value="red on green">