* { box-sizing: border-box; }

body {
  font-family: Arial, Helvetica, sans-serif;
  margin: 0;
  line-height: 1.4;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 16px;
}

.card {
  border: 1px solid #ddd;
  border-radius: 12px;
  padding: 16px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.field label {
  display: block;
  margin-bottom: 6px;
  font-weight: bold;
}

.field input {
  width: 100%;
  padding: 10px;
  border: 1px solid #bbb;
  border-radius: 8px;
}

.actions {
  margin-top: 12px;
  display: flex;
  gap: 10px;
}

button {
  padding: 10px 14px;
  border-radius: 10px;
  border: 1px solid #999;
  cursor: pointer;
}

.results {
  margin-top: 18px;
}

.output {
  background: #f6f6f6;
  padding: 12px;
  border-radius: 10px;
  border: 1px solid #ddd;
}

.error {
  color: #b00020;
  font-weight: bold;
}

@media (max-width: 700px) {
  .grid {
    grid-template-columns: 1fr;
  }
}