Hello @JCarlosF!
In this case the radio ballots are actually an image composite of sprites. This is going to require a little more elaborate CSS skills to handle.
In summary you need to:
1. download the referred image sprite file by its CSS setting (
/extjs/packages/theme_crisp/build/resources/images/form/radio-png/ext.axd
)
2. edit it in an image editor to make it look the way you want it to
3. place it somewhere in your webpage
4. override the css to point to the customized file, something like:
.my-field-style .x-form-radio-default {
background: url(path-to/my-custom-radio-sprite.png) no-repeat;
}
I think there are some CSS rules to set/colorize the image, it could be used to change the base color of the displayed image when and not hovered by the mouse pointer, without the need to download and edit the current image. But again, that's an advanced CSS topic and specific CSS skills are necessary to delve into this kind of customization.
Hope this helps!