.l4 {background: #330} /* rfc-1345 digraph */
.l5 {background: #030} /* ascii */
.l6 {background: #00331D} /* ascii */
+.l9 {background: #222}
.ex {background: #222} /* disfavoured */
.u-invalid {background: #333} /* impossible */
+.p4::after {color: #F44}
+.p3::after {color: #E66}
+.p2::after {color: #C88}
+.p1::after,
+.p0::after {color: #CCC}
+
/* general colorization */
.c-sa,