Markup for https://aebian.org/story/how-customize-octobercms-backend

markup.css

.layout #layout-mainmenu.navbar {
    background-color: #FFF;
    border-bottom: 1px solid #DDD;
}
.layout #layout-mainmenu.navbar ul li {
    text-align: center;
    padding: 0 15px;
    margin-right: 3px;
}
.layout #layout-mainmenu.navbar ul li a {
    font-weight: 400;
    text-transform: uppercase;
}
.layout #layout-mainmenu.navbar ul li a i {
    color: #90C3D4;
    font-size: 2rem;
    display: block;
    margin: 0;
    padding-bottom: 10px;
}
.layout #layout-mainmenu.navbar ul li.preview a i {
    padding-bottom: 0;
}

.layout #layout-mainmenu.navbar ul li.account a {
    padding: 13px;
}
.layout #layout-mainmenu.navbar ul li.active,
.layout #layout-mainmenu.navbar ul li.highlight,
.layout #layout-mainmenu.navbar ul li:hover{
    background-color: #EDEDED;
    color: inherit !important;
}
.layout #layout-mainmenu.navbar ul li.active a,
.layout #layout-mainmenu.navbar ul li.highlight a{
    color: inherit !important;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu{
    background-color: #FFF;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu:after{
    border-bottom-color: #FFF;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu li {
    border-bottom: 1px solid transparent;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu li:hover {
    background-color: #EDEDED !important;
    border-bottom-color: #CCC;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu li.divider{
    background-color: #CCC;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu li.divider+li{
    background-color: #555555;
    color: #FFF;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu li.divider+li:hover {
    background-color: #666 !important;
    border-bottom-color: transparent;
}
.layout #layout-mainmenu.navbar ul li .mainmenu-accountmenu li.divider+li:hover a {
    color: #FFF !important;
}

/* SIDENAV */
.sidenav-tree, #layout-sidenav {
    border-right: 1px solid #DDD;
}
.sidenav-tree ul.top-level > li > div.group h3 {
    background-color: #90C3D4;
}
.sidenav-tree ul.top-level > li[data-status="collapsed"] > div.group h3{
    background-color: #F2F2F2;
}
.sidenav-tree ul.top-level > li > div.group h3{
    color: #FFF;
}
.sidenav-tree ul.top-level > li > ul li.active a {
    background-color: transparent;
}
.sidenav-tree ul.top-level > li > ul li.active a span.header,
.sidenav-tree ul.top-level > li > ul li.active a span.description,
.sidenav-tree ul.top-level > li > ul li a,
.sidenav-tree ul.top-level > li > ul li a span.header,
.sidenav-tree ul.top-level > li > ul li a span.description{
    color: #777;
}
.sidenav-tree ul.top-level > li > div.group h3::before {
    color: #FFF;
}
.sidenav-tree ul.top-level > li[data-status="collapsed"] > div.group h3::before {
    color: #90C3D4;
}
.sidenav-tree ul.top-level > li > ul li.active {
    background-color: #E0E0E0;
}
.sidenav-tree ul.top-level > li[data-status="expanded"] > div.group h3{
    background-color: #90C3D4;
    color: #FFF;
}
.sidenav-tree ul.top-level > li[data-status="expanded"] > div.group h3:before {
    color: #FFF;
}
.sidenav-tree ul.top-level > li > ul li a i {
    color: #90C3D4;
}

/* SIDENAV SMALL */
#layout-sidenav ul li a {
    color: #777;
}
#layout-sidenav ul li a i {
    color: #90C3D4;
}
#layout-sidenav ul li.active, #layout-sidenav ul li:hover {
    background-color: #90C3D4;
}

.control-scrollpanel {
    background-color: #F7F7F7;
}
.responsive-sidebar .form-sidebar, #layout-side-panel {
    border-left: 1px solid #DDD;
}