.CodeMirror .interactive-php-linter-gutter {
    width: 23px;
}

.CodeMirror .interactive-php-linter-gutter-icon {
    background-image: url(../img/warning-icon.png);
    background-size: 15px 15px;
    background-repeat: no-repeat;
    margin-left: 7px;
    cursor: pointer;
}