* { box-sizing: border-box; }
body {
  margin: 0; min-height: 100vh; display: grid; place-items: center; padding: 1rem;
  font: 16px/1.5 system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: #f3f5f9; color: #1c2333;
}
.card {
  width: 100%; max-width: 480px; background: #fff; padding: 2rem;
  border-radius: 12px; box-shadow: 0 4px 24px rgba(20, 30, 60, .08);
}
h1 { margin: 0 0 .25rem; font-size: 1.5rem; }
.sub { margin: 0 0 1.5rem; color: #5b6477; }
label { display: block; margin-bottom: 1rem; font-weight: 600; font-size: .9rem; }
input, textarea {
  display: block; width: 100%; margin-top: .35rem; padding: .65rem .75rem;
  font: inherit; font-weight: 400; border: 1px solid #c9d0dd; border-radius: 8px;
}
input:focus, textarea:focus { outline: 2px solid #3b6cf6; outline-offset: 1px; border-color: transparent; }
.err { display: block; min-height: 1em; margin-top: .2rem; color: #c0392b; font-weight: 400; font-size: .8rem; }
button {
  width: 100%; padding: .75rem; font: inherit; font-weight: 600; color: #fff;
  background: #3b6cf6; border: 0; border-radius: 8px; cursor: pointer;
}
button:disabled { opacity: .6; cursor: wait; }
#status { margin: 1rem 0 0; text-align: center; font-weight: 600; }
#status.ok { color: #1e8e4e; }
#status.fail { color: #c0392b; }
.hp { position: absolute; left: -9999px; height: 0; overflow: hidden; }