*{box-sizing:border-box}
body{margin:0;min-height:100vh;display:flex;align-items:center;justify-content:center;
  font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  background:linear-gradient(135deg,#c62828,#6a1b1b);padding:16px}
.tarjeta{background:#fff;width:100%;max-width:380px;border-radius:16px;padding:28px 24px;box-shadow:0 10px 30px rgba(0,0,0,.3)}
h1{margin:0;text-align:center;font-size:1.6rem}
.sub{text-align:center;color:#666;margin:6px 0 20px}
.tabs{display:flex;gap:6px;margin-bottom:16px}
.tab{flex:1;padding:10px;border:0;border-radius:8px;background:#f0f0f0;cursor:pointer;font-size:.95rem}
.tab.activa{background:#c62828;color:#fff}
label{display:block;margin-bottom:12px;font-size:.9rem;color:#333}
input{width:100%;margin-top:4px;padding:11px;border:1px solid #ccc;border-radius:8px;font-size:1rem}
input:focus{outline:2px solid #c62828;border-color:transparent}
.solo-registro{display:none}
.modo-registro .solo-registro{display:block}
.msg{min-height:1.2em;color:#c62828;font-size:.88rem;margin:4px 0 10px}
.btn{width:100%;padding:12px;border:0;border-radius:8px;background:#c62828;color:#fff;font-size:1rem;cursor:pointer}
.btn:disabled{opacity:.6;cursor:wait}