.sound-control-btn.sound-on{background:var(--primary-color);border-color:var(--primary-color);color:#fff;box-shadow:0 0 20px rgba(0,0,0,.35)}.sound-control-btn.sound-on::before{content:"";position:absolute;inset:0;border-radius:50%;border:2px solid var(--primary-color);animation:soundPulse 1.6s infinite}