#calc-in-section {
  background-color: #1f2937; /* dark slate */
  color: #e5e7eb; /* light gray */
  padding: 3rem 1.5rem;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  max-width: 1200px;
  margin: 0 auto;
  margin-top: 6rem;
  border-radius: 12px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
}

#calc-in-title h2 {
  font-size: 2.5rem;
  font-weight: 700;
  color: rgb(59, 130, 246);
  margin-bottom: 0.25rem;
  text-align: center;
}

#calc-in-title p {
  font-size: 1.125rem;
  color: #9ca3af;
  text-align: center;
  margin-bottom: 2rem;
}

#in-out-container {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

#input-div, #output-div {
  background-color: #374151;
  border-radius: 10px;
  padding: 1.5rem 2rem;
  flex: 1 1 350px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
}

#input-div h3 {
  color: rgb(125, 163, 225);
  font-weight: 600;
  margin-top: 1rem;
  margin-bottom: 0.5rem;
}

select#package {
  width: 100%;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  border: none;
  font-size: 1rem;
  margin-bottom: 1.5rem;
  color: #111827;
  background-color: #dedede;
  cursor: pointer;
}

input[type="range"].slider {
  width: 100%;
  margin: 0.25rem 0 1rem 0;
}

output {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: #d1d5db;
  text-align: center;
}

.checkboxes-container {
  margin-top: 1rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px;
}

.container {
  position: relative;
  padding-left: 28px;
  cursor: pointer;
  user-select: none;
  font-size: 1rem;
  color: #d1d5db;
}

.container input {
  position: absolute;
  opacity: 0;
  cursor: pointer;
  height: 0;
  width: 0;
}

.checkmark {
  position: absolute;
  left: 0;
  top: 0;
  height: 20px;
  width: 20px;
  background-color: #4b5563;
  border-radius: 4px;
  transition: background-color 0.3s ease;
}

.container:hover input ~ .checkmark {
  background-color: #6b7280; /* gray-500 */
}

.container input:checked ~ .checkmark {
  background-color: rgb(59, 130, 246);
}

.checkmark:after {
  content: "";
  position: absolute;
  display: none;
}

.container input:checked ~ .checkmark:after {
  display: block;
}

.container .checkmark:after {
  left: 7px;
  top: 3px;
  width: 6px;
  height: 12px;
  border: solid white;
  border-width: 0px 3px 3px 0;
  transform: rotate(45deg);
}

#output-div h2 {
  color: rgb(82, 139, 231);
  font-weight: 700;
  margin-bottom: 1rem;
  text-align: center;
}

#output-div h5 {
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: #cbd5e1;
}

#output-list {
  list-style: none;
  padding-left: 0;
  margin-bottom: 1.5rem;
  color: #e0e7ff;
  min-height: 80px;
}

#output-list li {
  padding: 0.3rem 0;
  border-bottom: 1px solid #4b5563;
}

#output-div h4 {
  text-align: center;
  font-size: 1.5rem;
  font-weight: 700;
  color: rgb(82, 139, 231);
  border-top: 2px solid rgb(59, 130, 246);
  padding-top: 0.75rem;
}

#calculator-disclaimer {
  color: #8b8e94;
  max-width: 1200px;
  text-align: center;
  font-size: 18px;
}