/* class7-math-ch4-arith.css - Chapter 4 Tier 4 "Revisiting Arithmetic Expressions"
   (arFind, arNeg, arSwap, arBracket, arSeven, arVocab).
   Almost everything is shared (class7-math-ch2-common.css + class7-math-ch4-common.css); only Tier 4 touches live here. */
/* swap and group: the dotted arcs between friendly terms slowly march, so children see them "join" */
.c72-overlay[id^="arswap"] .c72-svg path[stroke-dasharray] { animation: c74-march 1.6s linear infinite; }
@keyframes c74-march { to { stroke-dashoffset: -20; } }