nav {
  background-color: #f8f9fa;
  box-shadow: 2px 0 4px rgba(0, 0, 0, 0.1);
  font-family: cursive;
  /* position: fixed; */
  float: left;
  left: 0;
  top: 0px;
  bottom: 0;
  width: 250px;
  overflow-y: auto;
  /* z-index: 1000; */
}

nav ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
}

nav li {
  position: relative;
  border-bottom: 1px solid #e1e1e1;
}

nav a {
  display: block;
  padding: 12px 15px;
  color: #333;
  text-decoration: none;
  transition: all 0.3s ease;
}

nav a:hover {
  background-color: #e9ecef;
  color: #0056b3;
  padding-left: 20px;
}

/* Obsah stránky - odsazení kvůli navigaci */
body {
  /* margin-left: 250px; */
}

/* Aktivní položka */
nav a.active {
  background-color: #007bff;
  color: white;
  font-weight: 500;
  border-left: 4px solid #0056b3;
}

li.zapocet {
  background-color: #e2f5cf;
}

li.zkouska {
  background-color: #e8b5e2;
}

/* Responzivní chování */
@media (max-width: 992px) {
  nav {
    width: 200px;
    font-family: "Segoe UI", "Roboto",
      "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji",
      "Segoe UI Emoji", "Segoe UI Symbol";
  }

  body {
    margin-left: 200px;
  }
}

@media (max-width: 768px) {
  nav {
    width: 180px;
    font-family: "Segoe UI", "Roboto",
      "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji",
      "Segoe UI Emoji", "Segoe UI Symbol";
  }

  body {
    margin-left: 180px;
  }

  nav a {
    padding: 10px 12px;
    font-size: 14px;
  }
}

@media (max-width: 576px) {
  nav {
    position: static;
    width: 100%;
    height: auto;
    max-height: 200px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    font-family: "Segoe UI", "Roboto",
      "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji",
      "Segoe UI Emoji", "Segoe UI Symbol";
  }

  body {
    margin-left: 0;
  }

  nav ul {
    flex-direction: row;
    flex-wrap: wrap;
  }

  nav li {
    border-bottom: none;
    border-right: 1px solid #e1e1e1;
    flex: 1 0 auto;
  }

  nav a:hover {
    padding-left: 15px;
  }

  nav a.active {
    border-left: none;
    border-bottom: 4px solid #0056b3;
  }
}

/* Styly pro rozbalovací menu na velmi malých obrazovkách */
@media (max-width: 400px) {
  nav {
    max-height: none;
    font-family: "Segoe UI", "Roboto",
      "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji",
      "Segoe UI Emoji", "Segoe UI Symbol";
  }

  nav.collapsible ul {
    display: none;
  }

  nav.collapsible.active ul {
    display: flex;
  }

  nav.collapsible::before {
    content: "☰ Menu";
    display: block;
    padding: 12px;
    background: #007bff;
    color: white;
    cursor: pointer;
    text-align: center;
    font-weight: bold;
  }

  nav.collapsible.active::before {
    content: "✕ Zavřít";
  }
}