fixed navbar with hamburger code example

Example 1: fixed navigation menu

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  height: 1200px;
  font-size: 18px;
  font-family: sans-serif;
  color: #5D6063;
}

a:link,
a:visited {
  color: #5D6063;
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

.header {
  position: fixed;
  display: flex;
  justify-content: space-between;
  
  width: 100%;
  padding: 50px;
  background: #D6E9FE;
}

Example 2: divi fixed and hamburger navigation setup

@media screen and (max-width: 980px) {
 .container { 
 width: 100% !important;
 }
 .et_header_style_left .logo_container{
 padding-left: 25px;
 }
 .et_header_style_centered #main-header .mobile_nav {
 background-color: transparent;
 }
 .mobile_nav.closed .select_page {
 display: none;
 }
 .et-fixed-header#main-header {
 background-color: transparent !important;
 }
}
.et_mobile_menu {
 top: 0 !important;
 border-top: 3px solid #283fc0 !important;;
 background-color: #fff !important;
 padding: 20% 0;
}
.et_mobile_menu li a {
 text-align: center;
 font-size: .8em;
 border: 0;
 padding: 15px 0;
 letter-spacing: 1px;
}
.mobile_nav ul#mobile_menu .current_page_item > a {
 color: #283fc0;
}
.mobile_nav ul#mobile_menu li ul li a {
 font-size: .8em !important;
 margin: auto;
 color: #363636 !important;
 padding-top: 0.2em;
}
.et_mobile_menu li a:hover {
 color: #999;
 -webkit-transition: all .2s ease-in-out;
 transition: all .2s ease-in-out;
}
.mobile_menu_bar:before {
 padding-right: 25px;
 color: #363636 !important;
}
.mobile_nav.opened .mobile_menu_bar:before {
 content: "\4d";
 z-index: 99999;
}

/* NESTING MOBILE MENU SETTINGS */
#et_mobile_nav_menu .mobile_nav.opened .mobile_menu_bar::before {
 content: '\4d';
}

#top-menu .menu-item-has-children .menu-item-has-children > a:first-child::after, 
#et-secondary-nav .menu-item-has-children .menu-item-has-children > a:first-child::after {
 content: '5'; 
}

#main-header #mobile_menu.et_mobile_menu .menu-item-has-children {
 position: relative; 
}

#main-header #mobile_menu.et_mobile_menu .sub-menu-toggle {
 position: absolute;
 background-color: rgba(0,0,0,0.03);
 z-index: 1;
 width: 36px;
 height: 36px;
 line-height: 36px;
 border-radius: 50%;
 top: 6px;
 right: 10px;
 cursor: pointer;
 text-align: center;
}

#main-header #mobile_menu.et_mobile_menu .sub-menu-toggle.popped {
 background-color: rgba(0,0,0,0.1);
}

#main-header #mobile_menu.et_mobile_menu .sub-menu-toggle::before {
 font-family: "ETmodules" !important;
 font-weight: normal;
 font-style: normal;
 font-variant: normal;
 -webkit-font-smoothing: antialiased;
 -moz-osx-font-smoothing: grayscale;
 line-height: 36px;
 font-size: 24px;
 text-transform: none;
 speak: none;
 content: '\33';
}

#main-header #mobile_menu.et_mobile_menu .sub-menu-toggle.popped::before {
 content: '\32';
}

#main-header #mobile_menu.et_mobile_menu .sub-menu-toggle ~ ul.sub-menu {
 display: none !important;
 padding-left: 0;
}

#main-header #mobile_menu.et_mobile_menu .sub-menu-toggle.popped ~ ul.sub-menu {
 display: block !important;
 background-color: rgba(0,0,0,0.03);
}

 #main-header #mobile_menu.et_mobile_menu li li {
 padding-left: 0;
}

#main-header #mobile_menu.et_mobile_menu li a, 
#main-header #mobile_menu.et_mobile_menu li li a,
#main-header #mobile_menu.et_mobile_menu li li li a {
 padding-left: 20px;
 padding-right: 20px;
}

#main-header #mobile_menu.et_mobile_menu .menu-item-has-children .sub-menu-toggle + a {
 padding-right: 20px;
}

#main-header #mobile_menu.et_mobile_menu .menu-item-has-children > a {
 background-color: transparent;
 font-weight: inherit;
}

#main-header #mobile_menu.et_mobile_menu li.current-menu-item > a {
 font-weight: bolder;
}