MyFirstBlog/MyBlog/static/L_header.css

#mainNav .navbar-brand {
    color: #000 !important;
}

#mainNav .navbar-nav > li.nav-item > a {
    color: #000 !important;
}

#mainNav.is-fixed {
    background-color: rgba(240, 240, 240, 0.9) !important;
}
.search-icon:after {
  background-color: #000000!important;
}
.search-icon:before {
  background-color: #000000!important;
}
.search-icon {
  border: 3px solid #000000!important;
}
.search:before {
  background-color: #000000!important;
}
.search-box {
  color: #000000!important;
}