/* Bijące serce w stopce — podwójne uderzenie ("lub-dub") + przerwa, ~70 uderzeń/min */
.serce {
    display: inline-block;
    transform-origin: center;
    animation: serce-bicie 0.86s ease-in-out infinite;
    will-change: transform, filter;
}

@keyframes serce-bicie {
    0%   { transform: scale(1);    filter: drop-shadow(0 0 0 rgba(255, 40, 60, 0)); }
    12%  { transform: scale(1.32); filter: drop-shadow(0 0 4px rgba(255, 40, 60, .75)); } /* lub */
    24%  { transform: scale(0.96); filter: drop-shadow(0 0 1px rgba(255, 40, 60, .2)); }
    36%  { transform: scale(1.2);  filter: drop-shadow(0 0 3px rgba(255, 40, 60, .55)); } /* dub */
    52%  { transform: scale(1);    filter: drop-shadow(0 0 0 rgba(255, 40, 60, 0)); }
    100% { transform: scale(1);    filter: drop-shadow(0 0 0 rgba(255, 40, 60, 0)); }      /* przerwa */
}

@media (prefers-reduced-motion: reduce) {
    .serce { animation: none; }
}