html, body {height: 100%;}
body {
  margin: 0;
  color: #fff;
  background-color: #151a2e;
  display: grid;
  place-items: center;
  padding: 24px;
}
main {
  width: 100%;
  max-width: 450px;
  background: linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.01));
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 20px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.45), inset 0 1px 0 rgba(255,255,255,0.05);
  backdrop-filter: blur(8px);
  overflow: hidden;
}
main .card_header {
  padding: 20px 22px 0 22px;
}
main .card_header .title {
  margin: 0;
  font-size: 1.4rem;
  letter-spacing: 0.2px;
}
main .card_header .subtitle {
  margin: 6px 0 0;
  color: #777;
  font-size: 0.95rem;
}
main .form {
  padding: 18px 22px 22px;
  display: grid;
  gap: 14px;
}
main .form .physical { display: grid; gap: 8px; }
main .form .physical .spec {
  font-size: 0.9rem;
  color: #9aa3b2;
}
main .form .physical .input-wrap {
  position: relative;
}
main .form .physical input[type="number"] {
  width: 100%;
  background: #151a2e;
  color: #fff;
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 12px;
  padding: 14px 48px 14px 14px;
  font-size: 1rem;
}
main .form .physical input[type="number"]:focus {
  border-color: #5b8cff;
  box-shadow: 0 0 0 6px rgba(91,140,255,0.12);
}
main .form .physical .input-wrap .unit {
  position: absolute; inset: 0 12px 0 auto; height: 100%; display: grid; place-items: center;
  color: #9aa3b2;
  font-weight: 600; font-size: 0.95rem;
  pointer-events: none;
}
main .form .btn {
  margin-top: 6px;
  width: 100%;
  background: linear-gradient(180deg, #5b8cff, #4b78e0);
  color: white;
  border: none;
  border-radius: 12px;
  padding: 14px 16px;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.2px;
  cursor: pointer;
  box-shadow: 0 12px 30px rgba(91,140,255,0.35);
}
main .result {
  padding: 18px 22px 22px;
  border-top: 1px solid rgba(255,255,255,0.06);
  display: grid; gap: 10px;
}
main .result.hidden { display: none; }