Problems with html selects in firefox

I have a problem with html select, at the time that I view with firefox, it's like I broke the css styles.

The button associated with the select, shown divided into two different colors halved. A dark black and light black.

Here is the css code:

select{
    background:url("data:image/svg+xml;utf8,<svg xmlns='http://ift.tt/nvqhV5' width='50px' height='50px'><polyline points='46.139,15.518 25.166,36.49 4.193,15.519'/></svg>");
    background-repeat: no-repeat;
    background-position: right 10px top 15px;
    background-size: 16px 16px;
    color: #000000;
    padding: 12px;
    width: auto;
    font-family: arial,tahoma;
    font-size: 16px;
    /* font-weight: bold; */
    text-align: center;
    text-shadow: 0 -1px 0 rgba(0, 0, 0, 0.25);
    border-radius: 3px;
    -webkit-border-radius: 3px;
    -webkit-appearance: none;
    -moz-appearance: -moz-win-media-toolbox;
    border: 0;
    outline: 0;
    -webkit-transition: 0.3s ease all;
    -moz-transition: 0.3s ease all;
    -ms-transition: 0.3s ease all;
    -o-transition: 0.3s ease all;
    transition: 0.3s ease all;
    background-color: #a7a59e;
}