Highlighting Sliding Issue With Arabic in Safari

[ELKADUSUNhalifesi]

Selam thanks for the extension it was really helpful for my project: muqattacounter.github.io but I have issues with Safari it has renders JavaScript differently so that unified letter لا (LamElif) which consists from two letters ل+ا (Lam + Elif) highlighted twice in one at true position one at next character's position(false):

Because of this sliding all the next highlights becomes increasingly more false(more slided) as new لا unified letters comes in at next characters... And end result is this:

Firefox can separately highlight this two letters from middle(which is desired):

How can I do that like in the case of firefox at all browsers?