/* Basic resets */
* {
  box-sizing: border-box;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  margin: 0;
  padding: 0;
  line-height: 1.5;
  color: #333;
  background-color: #f8f9fa;
}

/* Navigation bar */
nav {
  background-color: #004080;
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 1000;
  width: 100%;
}

nav .nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

nav .logo {
  font-size: 1.5rem;
  margin: 0.5rem 0;
  font-weight: bold;
}

nav .nav-links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  margin: 0;
  padding: 0;
}

nav .nav-links li {
  margin: 0;
}

nav .nav-links li a {
  display: block;
  padding: 0.75rem 1rem;
  color: #fff;
  text-decoration: none;
  transition: background 0.2s ease-in-out;
}

nav .nav-links li a:hover,
nav .nav-links li a:focus {
  background-color: #003060;
}

/* Sections */
.section {
  max-width: 900px;
  margin: 2rem auto;
  padding: 1rem;
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.section h2 {
  margin-top: 0;
  color: #004080;
}

.calculator-form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 1rem;
}

.form-row {
  display: flex;
  flex-direction: column;
}

.form-row label {
  margin-bottom: 0.25rem;
  font-weight: bold;
}

.form-row input,
.form-row select {
  padding: 0.5rem;
  border: 1px solid #ccc;
  border-radius: 4px;
  width: 100%;
  font-size: 1rem;
}

button {
  align-self: flex-start;
  padding: 0.6rem 1.2rem;
  background-color: #004080;
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-size: 1rem;
  transition: background 0.2s ease-in-out;
}

button:hover,
button:focus {
  background-color: #003060;
}

.result {
  padding: 1rem;
  background-color: #e9f5ff;
  border: 1px solid #b3daff;
  border-radius: 4px;
  color: #004080;
  display: none;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  padding: 0.5rem;
  text-align: left;
  border-bottom: 1px solid #ddd;
}

th {
  background-color: #f1f5fb;
  color: #004080;
  font-weight: bold;
}

tr:hover {
  background-color: #f9fbff;
}

.hidden {
  display: none;
}

footer {
  padding: 1rem;
  background-color: #f0f0f0;
  text-align: center;
  font-size: 0.9rem;
  color: #666;
}

.print-btn {
  margin-top: 1rem;
}

@media (max-width: 768px) {
  nav .nav-links {
    flex-direction: column;
  }
  nav .nav-links li a {
    padding: 0.5rem;
  }
  .section {
    margin: 1rem;
    padding: 1rem;
  }
}