var/const/canCastStyle = {"
    body {
        color:green;
    }
"}
var/const/cantCastStyle = {"
    body {
        color:red;
    }
"}
Player
    proc
        updateSpellPanel()
            var/count = 0
            for(var/Spell/spell in contents)
                if(!istype(spell)) continue
                var/style
                if(spell.canCast(src))
                    style = canCastStyle
                else
                    style = cantCastStyle
                winset(src,"spellGrid","current-cell=[++count]")
                winset(src,"spellGrid","style=[style]")
                src << output(spell, "spellGrid")


            winset(src,"spellGrid","cells=[count]")