tildes-reextended/source/scss/scripts/_back-to-top.scss

#trx-back-to-top {
  bottom: 2vh;
  position: fixed;
  right: 2vw;
}

#trx-jump-to-new-comment:not(.trx-hidden) + #trx-back-to-top {
  bottom: 6.5vh;
}