/* Simple mobile‑friendly styling */
body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: #f0f2f5;
}
.container {
  background: #fff;
  padding: 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,.1);
  width: 100%;
  max-width: 320px;
}
h1 { text-align: center; margin-bottom: 1rem; }
label { display: block; margin-top: 0.5rem; }
input[type="number"] {
  width: 100%;
  padding: .5rem;
  margin-top: .25rem;
  box-sizing: border-box;
}
.options {
  margin: 1rem 0;
}
.options label { display: block; margin-top: .25rem; }
button {
  width: 100%;
  padding: .75rem;
  background: #0069d9;
  color: #fff;
  border: none;
  border-radius: 4px;
  font-size: 1rem;
  cursor: pointer;
}
button:hover { background: #0053a6; }
#result {
  display: block;
  margin-top: 1rem;
  word-break: break-all;
  text-align: center;
  font-weight: bold;
  font-size: 1.1rem;
}