.neon-card{background-color:var(--bg-color,#fff);border:2px solid transparent;border-radius:1rem;position:relative;box-shadow:0 0 10px rgba(255,0,0,.4),0 0 15px rgba(0,128,255,.4);transition:box-shadow .3s ease-in-out,background-color .3s ease-in-out}.neon-card:before{content:"";position:absolute;inset:0;border-radius:1rem;padding:2px;background:linear-gradient(90deg,#ff0000,#007bff,#ff0000);background-size:200% 200%;animation:neon-border 3s linear infinite;-webkit-mask:linear-gradient(#fff 0 0) content-box,linear-gradient(#fff 0 0);-webkit-mask-composite:xor;mask-composite:exclude}@keyframes neon-border{0%{background-position:0 50%}50%{background-position:100% 50%}to{background-position:0 50%}}html.dark .neon-card{--bg-color:#1f2937;box-shadow:0 0 8px rgba(255,0,0,.5),0 0 12px rgba(0,128,255,.5)}