.react-tabs__tab--selected { transition: 1s; border-top: 1px #00AA00 solid; } .tab-btn { background-color: #121212; transition: 1s; border-bottom: 1px #FFFFFF solid; } .btn-beg { border-bottom-left-radius: 10px; border-top-left-radius: 10px; border-left: 1px #FFFFFF solid; } .btn-end { border-bottom-right-radius: 10px; border-top-right-radius: 10px; border-right: 1px #FFFFFF solid; }