.page-activity-add{box-sizing:border-box;padding:30px}.page-activity-add .form{width:800px;margin:0 auto;padding:30px;background:linear-gradient(-135deg,transparent 34px,#f9f9f9 0),linear-gradient(-135deg,transparent 34px,#fff 0);background-size:50px 50px,100% 100%;background-position:100% 0;background-repeat:no-repeat;filter:drop-shadow(2px 2px 3px #ccc)}