There is no way to do that on Steemit. But instead of Steemit you can use the busy.org website where you have a bookmark function or something like that. It is also build on the Steem blockchain and gives an alternative layout. When you write comment or posts there it will be visible on Steemit as well. Same account and everything. But you need to enter your private posting key (not the other keys!!!) which you find in your Wallet under Permissions.