Change Details

### Background Currently we use visibility: hidden to hide dropdown contents when the dropdown is closed, which also hides the dropdown contents to screen reader users. However, dropdowns generally arent as important to screenreader users, and in the case of the Table of Contents, introduces extra steps and discoverability issues. Instead, we could use the visually hidden mixin to hide the dropdown contents ### AC [] Dropdowns are accessible to screenreaders even when closed

### Background Currently we use visibility: hidden to hide dropdown contents when the dropdown is closed, which also hides the dropdown contents to screen reader users. However, dropdowns generally arent as important to screenreader users, and in the case of the Table of Contents, introduces extra steps and discoverability issues. Instead, we could use the visually hidden mixin to hide the dropdown contents One concern is that this would essentially make the menu button do nothing, which could be unexpected ### AC [] Dropdowns are accessible to screenreaders even when closed

### Background Currently we use visibility: hidden to hide dropdown contents when the dropdown is closed, which also hides the dropdown contents to screen reader users. However, dropdowns generally arent as important to screenreader users, and in the case of the Table of Contents, introduces extra steps and discoverability issues. Instead, we could use the visually hidden mixin to hide the dropdown contents One concern is that this would essentially make the menu button do nothing, which could be unexpected ### AC [] Dropdowns are accessible to screenreaders even when closed