CSS Grid Animation (Firefox) code example

Example: how to apply grid size change transition

function changeGridTemplateColumns(pattern) {
  TweenMax.to(".container",
    1, {
      gridTemplateColumns: pattern
    }
  );
}

function changeGridTemplateRows(pattern) {
  TweenMax.to(".container",
    1, {
      gridTemplateRows: pattern
    }
  );
}

$(document).ready(
  function() {
    $(".el-a,.el-b,.el-c").mouseenter(
      function() {
        changeGridTemplateRows("2fr 1fr");
      }
    );
    $(".el-d,.el-e,.el-f").mouseenter(
      function() {
        changeGridTemplateRows("1fr 2fr");
      }
    );

    $(".el-a,.el-d").mouseenter(
      function() {
        changeGridTemplateColumns("2fr 1fr 1fr");
      }
    );

    $(".el-b,.el-e").mouseenter(
      function() {
        changeGridTemplateColumns("1fr 2fr 1fr");
      }
    );

    $(".el-c,.el-f").mouseenter(
      function() {
        changeGridTemplateColumns("1fr 1fr 2fr");
      }
    );

    $(".container").mouseleave(
      function() {
        changeGridTemplateColumns("1fr 1fr 1fr");
        changeGridTemplateRows("1fr 1fr");
      }
    );
  }
);