Smaller and/or more packed buttons (Workers/Equip/Artifact/etc) would allow you to stretch the height of the "lists" so we can see more items at the same time -> more items means less scrolling and less scrolling is fun.
Also, the white font on the yellow progress bar prevent us from seeing the text.
Hi, attack skills like "Strike" don't get cast when there is no monster. The hero's mana goes down, but the skill is "queued" and stacked until a monster appears, at which the hero will cast the skill without delay. Try clicking on Strike when there is no monster. I think the issue might be that your warrior killed a monster, but another hero attacked at the same time, causing him to look like he has hit air. I like your suggestion on "heal" though. I will make heal smarter (smart-cast?) only when there is health to heal. Thanks for the feedback!
Weird, but sounds like a browser issue.