Sorry for all the questions.
Add one of the following CSS codes under the "Advanced" section in Tree Style Tab's option page in the "Extra style rules for sidebar contents" textbox.
To remove close button completely:
.closebox {
display: none;
}
To hide close button (it still takes up space and can still be clicked on):
.closebox {
opacity: 0 !important;
}
To hide close button and allow clicks through it (it still takes up space but it can't be clicked on):
.closebox {
opacity: 0 !important;
pointer-events: none;
}
Most helpful comment
Add one of the following CSS codes under the "Advanced" section in Tree Style Tab's option page in the "Extra style rules for sidebar contents" textbox.
To remove close button completely:
To hide close button (it still takes up space and can still be clicked on):
To hide close button and allow clicks through it (it still takes up space but it can't be clicked on):