body {
  background-color: #121212;
  color: #fff;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  text-align: center;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
  text-align: center;
}

h1 span {
  color: #4caf50;
}

.chart-wrap {
  background-color: #121212;
  border-radius: 10px;
  padding: 10px;
  max-width: 900px;
  margin: 20px auto;
  height: 400px;
  position: relative;
}

#candlestickChart {
  width: 100% !important;
  height: 100% !important;
  display: block;
  background: #1e1e1e;
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(76, 175, 80, 0.6);
}

.opciones {
  margin: 20px 0;
}

.opciones button {
  padding: 10px 20px;
  margin: 0 10px;
  font-size: 16px;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  color: white;
  background-color: #333;
  transition: background-color 0.3s ease;
}

.opciones button:hover {
  background-color: #555;
}

.resultado {
  font-size: 18px;
  margin-top: 10px;
}

#timer {
  margin-top: 10px;
  color: #ccc;
}

.volver a {
  color: #4caf50;
  text-decoration: none;
}

.volver a:hover {
  text-decoration: underline;
}

@media (max-width: 600px) {
  .chart-wrap {
    height: 300px;
  }

  .opciones {
    display: flex;
    flex-direction: column;
    gap: 10px;
  }

  .opciones button {
    width: 80%;
    margin: 0 auto;
  }
}

.interval-selector {
  margin-bottom: 15px;
  color: #ccc;
  font-size: 16px;
}

.interval-selector label {
  margin-right: 8px;
}

.interval-selector select {
  padding: 8px 12px;
  background-color: #222;
  border: none;
  border-radius: 6px;
  color: white;
  font-size: 16px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

.interval-selector select:hover {
  background-color: #444;
}

.saldo-demo {
  max-width: 320px;
  margin: 25px auto 15px auto;
  padding: 18px 25px;
  border-radius: 12px;
  font-weight: 700;
  font-size: 1.6rem;
  user-select: none;
  text-align: center;
  box-shadow: 0 0 20px rgba(76, 175, 80, 0.8);
  cursor: default;
  color: #a5d6a7;
  background: linear-gradient(135deg, #1b5e20, #2e7d32);
  transition: box-shadow 0.3s ease, background-color 0.3s ease;
}

.saldo-demo:hover {
  box-shadow: 0 0 35px rgba(76, 175, 80, 1);
  background-color: #00796b;
}