Im looking to add an item button to the forum quick buttons like center, spoiler, code.

So when you click the item button it inserts [item=] into the form post box.

this is impossible to do unfortunately. css only makes visual changes - it can't input text into the forum post box

I use my iPhone when on this site most of the time. I find that I have put some words in text replacement feature. If you have an iPhone, settings, general, keyboard, text replacement. For [“item =] all I type in is “itm” and it inserts [“item = (without the spaces and quotes and then I backspace and insert the item name. If I type in two commas, it inserts “]” the closing bracket. Maybe that will help.

Text replace is a great idea I should add that to my phone too