#bac-calculator-container {
  max-width: 800px;
  margin: auto;
  padding: 20px;
  font-family: 'Segoe UI', sans-serif;
  background: #f7f9fc;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

#bac-calculator-container h1 {
  font-size: 24px;
  text-align: center;
  margin-bottom: 15px;
  color: #333;
}

#expr {
  width: 100%;
  font-size: 18px;
  padding: 10px;
  margin-bottom: 12px;
  border: 1px solid #ccc;
  border-radius: 5px;
  box-sizing: border-box;
}

#btn-panel {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 15px;
  justify-content: center;
}

#btn-panel button {
  padding: 8px 12px;
  font-size: 16px;
  background-color: #007acc;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  flex-grow: 1;
  max-width: 80px;
}

#btn-panel button:hover {
  background-color: #005fa3;
}

#calculate-btn {
  display: block;
  margin: 10px auto 20px;
  padding: 10px 20px;
  font-size: 18px;
  background-color: green;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

#calculate-btn:hover {
  background-color: darkgreen;
}

#output {
  margin-top: 20px;
  font-size: 16px;
  line-height: 1.6;
  color: #222;
}

#output pre {
  background: #eef;
  padding: 10px;
  border-radius: 5px;
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 15px;
  font-size: 14px;
}

th, td {
  padding: 8px;
  border: 1px solid #ccc;
  text-align: center;
}

button.share {
  margin: 10px 5px 0 0;
  padding: 10px 16px;
  font-size: 16px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

button.share.whatsapp {
  background-color: #25D366;
  color: white;
}

button.share.email {
  background-color: #0072C6;
  color: white;
}

/* Responsive */
@media (max-width: 600px) {
  #btn-panel {
    gap: 4px;
  }

  #btn-panel button {
    font-size: 14px;
    padding: 6px;
    max-width: 70px;
  }

  #calculate-btn {
    width: 100%;
  }

  #expr {
    font-size: 16px;
  }

  table {
    font-size: 12px;
  }
}