getting a weird blue color around a button only in chrome

getting a weird blue color around a button only in chrome

attach is a screen shot,for some reason when clicking on the button the
blue part appears.

this is the code I use for this buttons:
html:
<div style="display:table-cell;" class="btnRight">
<span class="scrollUp" onclick="mobile_scrollUp();"></span>
<div style="clear:both"></div>
<span class="scrollDown" onclick="mobile_scrollDown();"></span>
</div>
css:
.btnRight .scrollUp {
width: 35px;
height: 35px;
background: url(../images/up-down-arrows.png) 0px 0px no-repeat;
}
.btnRight .scrollUp {
width: 35px;
height: 35px;
background: url(../images/up-down-arrows.png) 0px 0px no-repeat;
}
.previews-status span {
margin: 7px 0 0 0;
display: inline-block;
cursor: pointer;
}