docs: README feature walkthrough with screenshots; css: .active wins over .nextup

static/style.css

@@ -113,9 +113,9 @@ button.tiny.on { border-color: var(--acc); color: var(--acc); }
 
 .eps { display: grid; grid-template-columns: repeat(auto-fill, minmax(64px, 1fr)); gap: 0.4rem; }
 .ep { position: relative; font-size: 0.9rem; }
-.ep.active { border-color: var(--acc); color: var(--acc); }
 .ep.filler { opacity: 0.55; }
 .ep.done { opacity: 0.5; }
 .ep.nextup { border-color: #4b5568; background: #1f2130; }
+.ep.active { border-color: var(--acc); color: var(--acc); }  /* declared last: wins over nextup */
 .badge { font-size: 0.6rem; color: var(--muted); }