.frm{top:-.2em;right:-.2em;bottom:-.2em;left:-.2em;color:red;box-shadow:0 0 .4px;filter:hue-rotate(40deg)}
.frm:after{border:solid .08em;background:
url(../mask/corner8a.svg).02em .02em/.7em,
url(../mask/corner8b.svg)calc(100% - .02em) .02em/.7em,
url(../mask/corner8c.svg)calc(100% - .02em) calc(100% - .02em)/.7em,
url(../mask/corner8d.svg).02em calc(100% - .02em)/.7em;
background-repeat:no-repeat;
filter:brightness(.6)url(#lightF4)
}