* {
  box-sizing: border-box;
  touch-action: manipulation;
}
body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f0f4f8;
  text-align: center;
  margin: 0;
  padding-top: 75px; /* Espacio para el header */
  /*padding: 75px;*/
  color: #333;
  -webkit-tap-highlight-color: transparent;
}
h1 {
  color: #2c3e50;
  font-size: 1.6rem;
  margin-bottom: 8px;
}
p {
  color: #555;
  font-size: 0.95rem;
  margin-bottom: 20px;
}

.final {
  font-size: 1.2rem;
  color: #fff;
  margin-top: 20px;
}

.container {
  max-width: 400px;
  margin: 0 auto;
  background: white;
  padding: 10px;
  border-radius: 15px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.1);
}

.display {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin: 25px 0;
}
.digit-box {
  width: 60px;
  height: 70px;
  font-size: 2rem;
  border: 2px solid #ccc;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: #fdfdfd;
  font-weight: bold;
  color: #2c3e50;
}
.digit-box.filled {
  border-color: #4CAF50;
  background-color: #f0fff0;
}

.teclado {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 20px 0;
}
.tecla {
  height: 60px;
  background-color: #ecf0f1;
  border: none;
  border-radius: 10px;
  font-size: 1.5rem;
  font-weight: bold;
  color: #2c3e50;
  cursor: pointer;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  transition: background-color 0.2s, transform 0.1s;
}
.tecla:active {
  background-color: #bdc3c7;
  transform: scale(0.95);
}
.tecla.borrar {
  background-color: #e74c3c;
  color: white;
}
.tecla.enviar {
  background-color: #3498db;
  color: white;
  /*grid-column: span 3;*/
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.actions {
  margin: 20px 0;
}
.btn-reiniciar {
  padding: 12px 24px;
  font-size: 1.1rem;
  background-color: #9b59b6;
  color: white;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: background-color 0.2s;
}
.btn-reiniciar:active {
  background-color: #8e44ad;
}

.resultados {
  margin-top: 0px;
  max-height: 200px;
  overflow-y: auto;
  text-align: left;
  font-size: 0.9rem;
  color: #555;
  padding: 10px;
  background-color: #f9f9f9;
  border-radius: 10px;
  border: 1px solid #eee;
}

.mensaje {
  font-size: 1.3rem;
  font-weight: bold;
  margin: 15px 0;
  min-height: 28px;
}
.mensaje.success {
  color: #27ae60;
}
.mensaje.error {
  color: #c0392b;
}

@media (max-width: 350px) {
  .digit-box { width: 50px; height: 60px; font-size: 1.7rem; }
  .tecla { height: 50px; font-size: 1.3rem; }
}