:root {
  --bg-1: #f5f7fb;
  --bg-2: #e6eefc;
  --card: #ffffff;
  --ink: #0f172a;
  --muted: #475569;
  --accent: #0ea5e9;
  --accent-2: #22c55e;
  --danger: #dc2626;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at top right, var(--bg-2), var(--bg-1));
  min-height: 100vh;
}

.layout {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.card {
  width: min(740px, 100%);
  background: var(--card);
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 12px 35px rgba(15, 23, 42, 0.12);
  animation: fade-in 350ms ease;
}

h1 {
  margin: 0 0 8px;
}

.subtitle {
  margin: 0 0 18px;
  color: var(--muted);
}

label {
  display: block;
  margin: 12px 0 8px;
  font-weight: 600;
}

select,
textarea,
button {
  width: 100%;
  border-radius: 10px;
  border: 1px solid #cbd5e1;
  font-size: 1rem;
}

select,
textarea {
  padding: 12px;
}

textarea {
  resize: vertical;
}

button {
  margin-top: 14px;
  padding: 12px;
  border: none;
  color: white;
  cursor: pointer;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  font-weight: 700;
}

button:hover {
  filter: brightness(1.03);
}

.result {
  margin-top: 18px;
  padding: 14px;
  border-radius: 10px;
  background: #f8fafc;
  border: 1px solid #dbeafe;
}

.error {
  margin-top: 14px;
  color: var(--danger);
  font-weight: 600;
}

.hidden {
  display: none;
}

pre {
  white-space: pre-wrap;
  word-break: break-word;
  background: #0b1220;
  color: #e2e8f0;
  padding: 10px;
  border-radius: 8px;
}

@keyframes fade-in {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}