body {
  font-family: Arial, sans-serif;
  background-color: #f2f2f2;
  color: #333333;
  margin: 0;
  padding: 0;
}

header {
  background-color: #333333;
  color: #ffffff;
  padding: 20px;
  text-align: center;
}

h1 {
  margin: 0;
  font-size: 28px;
}

.container {
  max-width: 800px;
  margin: 20px auto;
  padding: 20px;
  background-color: #ffffff;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

p {
  margin-bottom: 10px;
}

.feature {
  display: flex;
  align-items: center;
  margin-bottom: 20px;
}

.feature-icon {
  flex: 0 0 50px;
  margin-right: 10px;
}

.feature-text {
  flex: 1;
}

footer {
  background-color: #333333;
  color: #ffffff;
  padding: 10px;
  text-align: center;
}

.demo-section {
  margin-top: 40px;
}

.demo-form {
  margin-top: 20px;
}

.demo-form label {
  display: block;
  margin-bottom: 10px;
}

#demo-number {
  width: 80%;
  padding: 10px;
  margin-bottom: 10px;
}

.demo-form input[type="submit"] {
  background-color: #333333;
  color: #ffffff;
  border: none;
  padding: 10px 20px;
  cursor: pointer;
}

.demo-feature {
  display: flex;
  align-items: center;
  margin-bottom: 20px;
}

.demo-feature-icon {
  flex: 0 0 50px;
  margin-right: 10px;
}

.demo-feature-text {
  flex: 1;
}

.demo-paragraph {
  margin-top: 20px;
  font-size: 16px;
}

sub {
  display: block;
  margin-bottom: 10px;
}