Why doesn't the navigation color change

Hi i am writing this code to change my url based navigation link color but it is not working as expected please help me. I want to change the color of the navigation link for that specific url my js code

function big(x){

x.style.fontSize = "17px";
x.style.color="#03c1cb";
}
function small(x){
var y=location.hash;
if(x.href== y){
x.style.fontSize = "17px";
x.style.color="#03c1cb";
}
else{
x.style.color = "white";
x.style.fontSize ="15px";
}
}

      

        
        
        
      

    

and

function isElementInViewport (el) {
      //special bonus for those using jQuery
      if (typeof jQuery === "function" && el instanceof jQuery) {
        el = el[0];
      }
      var rect = el.getBoundingClientRect();
      return (
        rect.top >= 0 &&
        rect.left >= 0 &&
        rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && /*or $j(window).height() */
        rect.right <= (window.innerWidth || document.documentElement.clientWidth) /*or $j(window).width() */
      );
    }

// url change on clicking
$(document).ready(function () {
    $(".scroll").click(function (e) {
        e.preventDefault();
        var section = this.href,
            sectionClean = section.substring(section.indexOf("#"));

        $("html, body").animate({
            scrollTop: $j(sectionClean).offset().top
        }, 1000, function () {
            window.location.hash = sectionClean;
        });

    });
});
// listen for the scroll event
    $(document).on("scroll", function() {
      console.log("onscroll event fired...");
      // check if the anchor elements are visible
      $(".anchor").each(function (idx, el) {
        if ( isElementInViewport(el) ) {
          // update the URL hash
          if (window.history.pushState) {
            var urlHash = "#" + $j(el).attr("id");
            window.history.pushState(null, null, urlHash);
          }
        }
      });
    });

      

        
        
        
      

    

and my html code

<a href="#home" id="start1" class="scroll" style="text-decoration:none;position:absolute;right:450px;top:37px;font-weight:bold;color:white;font-size:15px;z-index:200;transition:0.5s"  onmouseover="big(this)" onmouseout="small(this)">HOME</a>

      

        
        
        
      

    

Please help me