rgba

There are 4 blocks, how many green ones? <div class="first"></div> <div class="second"></div> <div class="third"></div> <div class="fourth"></div> div{width:50px;height:50px;} .first{background: rgba(0,255,0,1);} .second{background: rgba(255,0,0,1);} .third{background: rgba(0,255,0,0);} .fourth{background: rgba(0,0,255,1);}