How to fix Z-index layering issue

Hello Everyone! So we recently designed this website

Currently the particle network animation (custom code) on header is not responsive (its supposed to generate particles where-ever user clicks) as it’s Z index is below the contact us button.

However, if we increase its Z-index, the contact us button stops responding.

Is there any solution to keep both active?

Here is my public share link:[0]=AT3-xUXIuynr4k5ZVW9h3kMvi6Zelz__aEirGFCiy87zDctve53N6OC2ckDG560idqOMDIOvzK0YcIIKSnmhqLVj2nuJmXytqYtZbOdHtrSShgpWiNv7mi4bwF_C9erbfTfNa803lOdqQRdDG4XzUkuNXZ0TpFcxp0nMoe57-_q2kguR_NtMN9BlClnfJu_cssCYk0GOMU5RY9mK9lH2GpY