Since the icons are already absolute positioning, then locate it using the transform and the coordinates of the top left and the button to put the sizes in even numbers:
.act-btn_circ .icon { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); } .act-btn_circ { display: block; width: 36px; height: 36px; border-radius: 50%; background-color: #fff; position: relative; box-shadow: 2px 4px 4px 0 rgba(0, 0, 0, 0.15); padding: 0; }