html, body {
  height: 100%;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  font-family: Arial, sans-serif;
  margin: 0;
  background: #f5f6fa;
  color: #333;
  line-height: 1.6;
  font-size: 1rem;
}

/* Header & nav */
header {
  background: #2f3640;
  color: white;
  padding: 1em;
  text-align: center;
}

header h1 {
  margin: 0 0 0.5em 0;
  font-size: 1.5rem;
}

nav a {
  color: #f5f6fa;
  margin: 0 0.8em;
  text-decoration: none;
  font-size: 1rem;
}

nav a:hover {
  text-decoration: underline;
}

/* Main content */
main {
  flex: 1;
  padding: 1.5em;
  background: white;
  margin: 1em;
  border-radius: 8px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
  box-sizing: border-box;
}

.container {
  max-width: 900px;
  margin: 2em auto;
  padding: 1em 2em;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  font-family: Arial, sans-serif;
}

section {
  margin-bottom: 2em;
  padding-bottom: 1em;
  border-bottom: 1px solid #eee;
}

h2 {
  font-size: 1.5rem;
  color: #2c3e50;
  margin-bottom: 1em;
}

/* Forms */
form {
  margin-top: 1em;
}

label, select, input {
  font-size: 1rem;
}

/* Text fields and select boxes */
select,
input[type="text"] {
  margin: 0.4em 0;
  padding: 0.4em;
  max-width: 100%;
  width: 100%;
  box-sizing: border-box;
}

/* Radio and checkboxes */
input[type="checkbox"],
input[type="radio"] {
  width: auto;
  margin-right: 0.5em;
  vertical-align: middle;
}

/* Buttons */
.btn,
button {
  display: inline-block;
  padding: 0.8em 1.2em;
  background: #40739e;
  color: white;
  border-radius: 6px;
  text-decoration: none;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  max-width: 100%;
  box-sizing: border-box;
  margin-top: 0.6em;
}

.btn:hover,
button:hover {
  background: #3498db;
}

/* Preformatted blocks */
pre {
  background: #f0f0f0;
  padding: 1em;
  border-radius: 6px;
  overflow-x: auto;
  font-size: 0.9rem;
}

/* Images */
.img-preview {
  max-width: 90%;
  height: auto;
  border: 1px solid #ccc;
  border-radius: 4px;
  margin-top: 0.5em;
}

.hidden {
  display: none;
}

/* Footer */
footer {
  text-align: center;
  font-size: 0.9rem;
  padding: 1em;
  color: #888;
}

/* Mobile */
@media (max-width: 600px) {
  header h1 {
    font-size: 1.2rem;
  }

  nav a {
    display: block;
    margin: 0.5em 0;
    font-size: 1.1rem;
  }

  main {
    margin: 0.5em;
    padding: 1em;
  }

  button, .btn, select  {
    width: 100%;
    font-size: 1rem;
    padding: 10px;
    border-radius: 6px;
    text-align: center;
  }

  ul {
    padding-left: 1em;
  }
}