Hi,
Look at the CSS of the button with the inspector and you'll understand:
take.ms/9sNlA
As you can see there, the color CSS code you defined is not taken into account as the one in the CSS code below supersedes it:
a.hikashop_cart_button, a.hikashop_compare_button, .hikashop_cart_input_button {
text-decoration: none;
color: #777777 !important;
cursor: pointer;
display: inline-block;
line-height: 18px;
margin: 5px;
padding: 3px 8px;
text-align: center;
box-shadow: none !important;
text-shadow: none !important;
border: 1px solid;
border-color: #EEEEEE #DDDDDD #DDDDDD #EEEEEE;
border-radius: 3px;
background-color: #eee;
background: -webkit-gradient(linear, left top, left bottom, from(#ffffff), to(#eee));
background: -webkit-linear-gradient(top, #ffffff, #eee);
background: -moz-linear-gradient(top, #ffffff, #eee);
background: -o-linear-gradient(top, #ffffff, #eee);
background: linear-gradient(top, #ffffff, #eee);
}
So you want to add !important in your CSS in order to supersedes that other CSS:
a.hikashop_cart_button{
color: #F22865 !important;
}