How to make css folded-corner effect with transparent background?

Someone can help me? I need to make the folded-corner to be transparent instead of solid color. You can see the picture below for your reference.

I have tried with these codes:

.back-ground
{
    background-image: url('http://pencil.my/assets/img/dashboard/bg.png');
    background-repeat: repeat;
    overflow-x: hidden;
}
.note {
    position: relative;
    width: 30px;
    padding: 1em 1.5em;
    margin: 2em auto;
    color: #fff;
    background: #97C02F;
    overflow: hidden;
    border-radius: 4px;
}

.note:before {
    content: "";
    position: absolute;
    top: 0;
    right: 0;
    border-width: 0 16px 16px 0;
    border-style: solid;
    border-color: #fff #fff #658E15 #658E15;
    background: #658E15;
    display: block;
    width: 0;
    -webkit-box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
    -moz-box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
    box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
}

<div class="back-ground">
 <div class="note">
    Sample note
 </div>
</div>