html {
  font-family: Helvetica;
  display: inline-block;
  margin: 0px auto;
  text-align: center;
}

nav {
  background-color: #2c3e50;
  padding: 0;
  margin: 0 auto;
  display: flex;
  justify-content: center;
  gap: 30px;
  position: sticky;
  top: 0;
  max-width: 900px;
  box-sizing: border-box;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

nav a {
  color: white;
  text-decoration: none;
  padding: 15px 20px;
  display: block;
  transition: background-color 0.3s;
  font-weight: 500;
}

nav a:hover {
  background-color: #34495e;
}

body {
  margin-top: 0px;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

h1 {
  color: #2c3e50;
  margin-top: 30px;
  margin-bottom: 20px;
}

h2 {
  color: #34495e;
  margin-top: 25px;
  margin-bottom: 15px;
  border-bottom: 2px solid #4CAF50;
  padding-bottom: 10px;
}

h3 {
  color: #444444;
  margin-bottom: 50px;
}

p {
  line-height: 1.6;
  color: #555;
  text-align: left;
  margin-bottom: 15px;
}

.section {
  text-align: left;
  margin: 30px 20px;
}

.highlight {
  background-color: #f0f8f0;
  padding: 20px;
  border-left: 4px solid #4CAF50;
  margin: 20px 0;
  border-radius: 4px;
}

ul {
  text-align: left;
  margin: 10px 0;
  padding-left: 20px;
}

li {
  margin-bottom: 8px;
  line-height: 1.6;
}

.footer {
  margin-top: 40px;
  padding: 20px;
  border-top: 1px solid #ddd;
  color: #888;
  font-size: 0.9em;
}

#chartbox {
  display: block;
  width: 600px;
}

label[for="file-input"] {
  padding: 12px 24px;
  font-size: 16px;
  background-color: #4CAF50;
  color: white;
  border-radius: 6px;
  cursor: pointer;
  transition: background-color 0.3s;
}

label[for="file-input"]:hover {
  background-color: #45a049;
}

#download-chart {
  padding: 12px 24px;
  font-size: 16px;
  background-color: #2196F3;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: background-color 0.3s;
}

#download-chart:hover {
  background-color: #0b7dda;
}