<div style="position:relative; background-color:#ecf; margin:15px 5px; padding:30px 10px 10px 10px; border:solid 1px #ddd; box-shadow:1px 2px 5px rgba(0,0,0,0.3);">左上にマステが貼られた紙に書く文章<div style="position:absolute; top:-10px; left:50px; display:block; transform:rotate(-5deg); -webkit-transform:rotate(-5deg); border-left:dotted 2px rgba(0,0,0,0.2); border-right:dotted 2px rgba(0,0,0,0.2); box-shadow: 0 0 3px rgba(0,0,0,0.3); background-color:rgba(255,255,255,.5); padding:3px 20px;font-size:1.2em;">マステに書く文字</div></div>