/*--------------------------------------------------------------
  Template Name: Simply Construction HTML Template.
  Template URI: #
  Description: Simply Construction is a unique website template designed in HTML with a simple & beautiful look. There is an excellent solution for creating clean, wonderful and trending material design corporate, corporate any other purposes websites.
  Author: DevItems
  Version: 1.0
---------------------------------------------------------------*/

/* ----------------------------------------------------
.logo {
    transition: opacity 0.3s ease-in-out;
}
.hide-logo {
    opacity: 0;
}
<script>
    window.addEventListener("scroll", function() {
        var logo = document.querySelector(".logo");
        if (window.scrollY > 50) {
            logo.classList.add("hide-logo");
        } else {
            logo.classList.remove("hide-logo");
        }
    });
</script>

-------------------------------------------------------*/