@keyframes blink {
    0%, 100% { opacity: 0.25; }
    50% { opacity: 1; }
}

@keyframes hb-sweep {
    from { stroke-dashoffset: 600; }
    to { stroke-dashoffset: 0; }
}

.hb-line {
    animation: hb-sweep 2.2s linear infinite;
    filter: drop-shadow(0 0 6px var(--brand)) drop-shadow(0 0 12px var(--brand-cyan));
}