Opacity Control the opacity of elements. The opacity property sets the opacity level for an element. The opacity level describes the transparency level, where 1 is not transparent at all, .5 is 50% visible, and 0 is completely transparent. Set the opacity of an element using .o-{value} utilities. 100% 80% 50% 20% 0% <div class="o-100">100%</div> <div class="o-80">80%</div> <div class="o-50">50%</div> <div class="o-20">20%</div> <div class="o-0">0%</div> Class Properties o-0 opacity: 0; o-10 opacity: .1; o-20 opacity: .2; o-30 opacity: .3; o-40 opacity: .4; o-50 opacity: .5; o-60 opacity: .6; o-70 opacity: .7; o-80 opacity: .8; o-90 opacity: .9; o-100 opacity: 1;