Template:Spoiler/styles.css

.pm-spoiler {
	filter: blur(0.5rem);
}

.pm-spoiler img,
.pm-spoiler figure,
.pm-spoiler iframe {
	filter: blur(1rem);
}

.pm-spoiler:hover,
.pm-spoiler:hover img,
.pm-spoiler:hover figure,
.pm-spoiler:hover iframe {
	filter: blur(0);
}