causeway-standard-theme/causeway/components/site-menu.less

// Menu
// --------------------------------------------------
.site-menu {
  clear: both;
  background-color: #f0f0f0;
  border: none;
  height: @site-menu-height;
  margin-bottom: 0;
  min-height: @site-menu-height;
  padding-left: 45px;
  .border-radius(0);
}