"animation-fill-mode: both" attribute clashes with the boostrap 3 modal popups.
It causes the class "modal-backdrop" to appear in front of all the others

If you remove the css attribute, it causes the content to flicker once before loading.
n.b. I am using animate.css along with wow js.
Any solutions?
Could you please share a reduced case on codepen showing the issue? It's really hard to debug anything from a screenshot.
Closing this as it's stale. Feel free to reopen it when you've got a reduced case.
Animate.css conflict with Bootsrap Modal because it have class animated fadeIn in the parent div.
To fix this issue, you need to remove class fadeIn on event show.bs.modal and put it back on event hidden.bs.modal.
Here is demo fix your issue: https://codepen.io/vndevil/pen/KBZOzb
Most helpful comment
Animate.css conflict with Bootsrap Modal because it have class
animated fadeInin the parentdiv.To fix this issue, you need to remove class
fadeInon eventshow.bs.modaland put it back on eventhidden.bs.modal.Here is demo fix your issue: https://codepen.io/vndevil/pen/KBZOzb