Colocar Borda no Quadro da Postagem

-webkit-border-top-right-radius: 20px;

-webkit-border-bottom-left-radius: 20px;

-moz-border-radius-topright: 20px;

-moz-border-radius-bottomleft: 20px;

border-top-right-radius: 20px;

border-bottom-left-radius: 20px;