fix: add colour for scrollbar

[ninetailedtori]

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[ninetailedtori]

(Tempted to add myself to the contributors list for this style now hahah :P)

[sgoudham]

(Tempted to add myself to the contributors list for this style now hahah :P)

Go for it 👍

[ninetailedtori]

Aaand this one should be good :]
Until micro adds selectively editing component colours based on hover, which isn't within its capabilities as of now, this is the farthest we can get with scrollbars, but for a possible future reference, #18 (comment) was discussed if it ever happens.