:root {
  --bg: #0f172a;
  --surface: #1e293b;
  --border: #334155;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --primary: #22d3ee;
  --accent: #a78bfa;
  --danger: #f87171;
  --radius: 14px;
}

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

body {
  font-family: 'Inter', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
  transition: background 0.35s ease;
}

.hub-back-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  display: inline-flex;
  align-items: center;
  padding: 0.4rem 0.75rem;
  border-radius: 999px;
  background: rgba(15, 23, 42, 0.9);
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 600;
  text-decoration: none;
  backdrop-filter: blur(8px);
}

.hub-back-link:hover { color: var(--primary); border-color: var(--primary); }

.prueba-header {
  text-align: center;
  padding: 3.5rem 1.5rem 1.5rem;
  border-bottom: 2px solid var(--primary);
}

.prueba-badge {
  display: inline-block;
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  background: rgba(34, 211, 238, 0.15);
  color: var(--primary);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.prueba-title {
  font-family: 'Bebas Neue', sans-serif;
  font-size: clamp(2rem, 7vw, 3rem);
  letter-spacing: 0.04em;
}

.prueba-desc {
  margin-top: 0.5rem;
  color: var(--text-muted);
  max-width: 32rem;
  margin-inline: auto;
}

.prueba-main {
  max-width: 640px;
  margin: 0 auto;
  padding: 2rem 1.5rem 3rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.prueba-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
}

.prueba-card h2 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.prueba-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
}

.prueba-btn {
  appearance: none;
  border: 1px solid var(--border);
  background: #0f172a;
  color: var(--text);
  padding: 0.55rem 1rem;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s, transform 0.1s;
}

.prueba-btn:hover { border-color: var(--primary); }
.prueba-btn:active { transform: scale(0.97); }

.prueba-btn-primary {
  background: var(--primary);
  color: #0f172a;
  border-color: var(--primary);
}

.prueba-btn-accent {
  background: var(--accent);
  color: #0f172a;
  border-color: var(--accent);
}

.prueba-btn-danger {
  background: transparent;
  color: var(--danger);
  border-color: var(--danger);
}

.prueba-counter {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 3rem;
  line-height: 1;
  min-width: 3rem;
  text-align: center;
  color: var(--primary);
}

.prueba-output {
  margin-top: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: 10px;
  background: rgba(0, 0, 0, 0.25);
  border: 1px dashed var(--border);
  color: var(--text-muted);
  font-size: 0.9rem;
  min-height: 2.5rem;
}

.prueba-log {
  margin-top: 0.75rem;
  max-height: 120px;
  overflow-y: auto;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.prueba-log p { padding: 0.2rem 0; }