Heading with fluid font-size

25px

150px

#top .av-special-heading.fluid-font .av-special-heading-tag {font-size: clamp(25px, 7vw, 150px) !important;}

/**** maybe more browser compliant:  ****/

#top .av-special-heading.fluid-font .av-special-heading-tag {
  font-size: min(max(25px, calc(1.5625rem + ((1vw - 3.2px) * 10.5042))), 150px);
  min-height: 0vw;
}