textarea.css

#SourceContainer {
    background-color: transparent;
    display: inline-block;
    padding: 0;
    margin: 0;
    padding-left: 86px;
    /* border: 1px solid black; */
    position: relative;
    text-align: left;
    overflow: hidden;
    font-size: 15px;
    font-family: monospace;
    /* width: 100%; */
}

#Source {
    background-color: transparent;
    display: inline;
    width: 600px;
    min-width: 300px;
    height: 400px;
    min-height: 250px;
    /* margin-left: 46px;  */
    font-family: monospace;
    font-size: 15px;
    line-height: 17px;
    position: relative;
    margin: 0px;
}


#SourceBackground {
    /* border: 1px solid red; */
    position: absolute;
    left: 40px;
    top: 2px;
    width: 100%;
    z-index: 0;
    font-family: monospace;
    font-size: 15px;
    text-align: left;
}

#tabackground {
    background: white;
    z-index: -4;
    display: block;
    /* border: 1px solid green; */
}


.talinenum {
    display: inline-block;
    width: 40px;
    padding-left: 3px;
    padding-right: 3px;
    background-color: darkgrey;
    text-align: center;
    /* position: relative; */
    overflow: hidden;
}

.talinebg {
    width: 100%;
    background-color: white;
    position: relative;
    height: 17px;
}
    .talinebg .talinebgnonum {
        padding-left: 40px;
    }

.talinebgnext {
    background-color: #bbf8ff;
}

.talinebgnext > .talinenum {
    /* background-color: #bbf8ff; */
}

.talinebgprev {
    background-color: #ffcc99;
}

.talinebgprev > .talinenum {
    /* background-color: #ffcc99; */
}

.talinebgerror {
    background-color: #ffe0e0;
}


/* 'Next' box */
#NextLineMarker {
    border-left: 1px solid #333333;
    border-top: 1px solid #333333;
    border-bottom: 1px solid #333333;
    border-right: 0;
    position: absolute;
    left: -40px;
    top: 1px;
    width: 38px;
    height: 14px;
    background: #bbf8ff;
    font-family: monospace;
    font-size: 13px;
/*    display: table-cell;
    vertical-align: middle; */ /* Not working!? */
    text-align: left;
    padding-left: 2px;
    z-index: 2;
}

#NextLineMarker.shifted {
    top: 3px;
    left: -36px;
}

/* Arrow outline */
#NextLineMarkerEnd:before {
    position: absolute;
    content: "";
    top: -1px;
    left: 40px;
    width: 0;
    height: 0;
    border-top: 8px solid transparent;
    border-bottom: 8px solid transparent;
    border-left: 8px solid #333333;
}

/* Arrow interior */
#NextLineMarkerEnd:after {
    position: absolute;
    content: "";
    width: 0;
    height: 0;
    top: -2px;
    left: 40px;
    margin-top:2px;
    margin-left:0px;
    border-top: 7px solid transparent;
    border-bottom: 7px solid transparent;
    border-left: 7px solid #bbf8ff;
}

/* 'Prev' box */
#PrevLineMarker {
    border-left: 1px solid #333333;
    border-top: 1px solid #333333;
    border-bottom: 1px solid #333333;
    border-right: 0;
    position: absolute;
    left: -40px;
    top: 1px;
    width: 38px;
    height: 14px;
    background: #ffcc99;
    font-family: monospace;
    font-size: 13px;
/*    display: table-cell;
    vertical-align: middle; */ /* Not working!? */
    text-align: left;
    padding-left: 2px;
    z-index: 1;
}

#PrevLineMarker.shifted {
    top: -1px;
}


/* Arrow outline */
#PrevLineMarkerEnd:before {
    position: absolute;
    content: "";
    top: -1px;
    left: 40px;
    width: 0;
    height: 0;
    border-top: 8px solid transparent;
    border-bottom: 8px solid transparent;
    border-left: 8px solid #333333;
}

/* Arrow interior */
#PrevLineMarkerEnd:after {
    position: absolute;
    content: "";
    width: 0;
    height: 0;
    top: -2px;
    left: 40px;
    margin-top:2px;
    margin-left:0px;
    border-top: 7px solid transparent;
    border-bottom: 7px solid transparent;
    border-left: 7px solid #ffcc99;
}

/* Syntax error message box */
#SyntaxMsg {
    /* background: #ffdddd; */
    color: #ff0000;
    margin-left: 86px;
}