when u work with porcents on CSS, i would like to recomend use 'min-' and 'max-' properties, to set the min and max size of ur element...
to solve that problem, u can add 'min-width: 50px;' to the class '.features-2 span'
.features-2 span {
font-weight:700;
width:16%;
min-width:70px; / add this property to control the min size/
text-align:left;
display:block;
float:left;
}
hope to be helpful 