CSS складывается угол
.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);
}
Duck Duck Go-ogle