* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: system-ui, sans-serif;
  background: #0f172a;
  color: white;
  min-height: 100vh;
}

header {
  text-align: center;
  padding: 50px 20px;
}

header h1 {
  font-size: 48px;
  margin-bottom: 10px;
}

header p {
  color: #94a3b8;
  font-size: 20px;
}

.container {
  width: min(1000px, 90%);
  margin: auto;
  padding-bottom: 60px;
}

.card {
  background: #1e293b;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
}

.card-header {
  background: #2563eb;
  padding: 20px;
}

.card-header h2 {
  font-size: 24px;
}

#output {
  padding: 25px;
  font-size: 16px;
  line-height: 1.8;
  white-space: pre-wrap;
  color: #22c55e;
  font-family: Consolas, monospace;
}

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 24px;
  padding: 12px 22px;
  background: #2563eb;
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  border-radius: 10px;
  transition: all 0.25s ease;
}

.back-btn:hover {
  background: #1d4ed8;
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(37, 99, 235, 0.35);
}