body {
    background-repeat: no-repeat;
    background-size: 100% 100%;
    height: 100%;
    background-repeat: no-repeat;
    background: url('ImagenesIBISNuevas/LogoUnidad.jpg')no-repeat center center fixed;
    background-size: 100% 100%;
}
fieldset{
    border: 0px solid rgb(255,232,57);
    width: 200px;       
    height: 200px;
    position: absolute;
    top:43%;
    left: 30%;           
    margin-top: -100px;
    margin-left: -100px;
}
input[type="text"], input[type="password"] {
    background-color: #fff;
    border-radius: 0px 3px 3px 0px;
    color: #000;
    margin-bottom: 1em;
    padding: 0 16px;
    width: 200px;
    height: 50px;
    font-family: inherit;
    font-size: inherit;
    line-height: inherit;
}
span.fa {
    background-color: #fff;
    border-radius: 0px 3px 3px 0px;
    color: #000;
    margin-bottom: 1em;
    padding: 0 16px;
    width: 200px;
    height: 50px;
    font-family: inherit;
    font-size: inherit;
    line-height: inherit;
}
.fa-lock:before {
    content: "\f023";
}