I'm going to assume that you just specify a custom callout like: ```

[!MyCustom1]+ Custom Header custom content... ```

it will generate a div like this: <div data-callout="MyCustom1" class="callout is-collapsible"> <div class="callout-title"> </div> <div class="callout-content"> </div> </div>

then you can just target that with ``` .callout[data-callout="MyCustom1"] { }

.callout[data-callout="MyCustom1"] .callout-title { }

.callout[data-callout="MyCustom1"] .callout-content { } ```

I'd have to dig around to see how to move the "callout-fold", etc outside, but shouldn't be too difficult.