:root {
  --primary: #1b5e20;
  --accent: #ffc107;
  --light-bg: #f4f4f4;
  --dark-text: #212121;
}

body {
  font-family: 'Roboto', sans-serif;
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: row;
  background: #fff;
  color: var(--dark-text);
}

.sidebar {
  background: var(--primary);
  color: #fff;
  padding: 1rem;
  width: 160px;
  box-sizing: border-box;
}

@media (min-width: 769px) {
  .sidebar {
    min-height: 100vh;
  }
}

.sidebar h3 {
  font-size: 1em;
  margin-top: 0;
  color: var(--accent);
}

.sidebar a {
  display: block;
  margin: .5rem 0;
  text-decoration: none;
  color: #fff;
  font-weight: bold;
}

.sidebar a:hover {
  text-decoration: underline;
}

.main {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  width: calc(100% - 160px);
}

header {
  background: var(--primary);
  color: #fff;
  padding: 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
}

.title-block a {
  color: #fff;
  text-decoration: none;
}

.title-block a:hover {
  text-decoration: underline;
}

.title-block h1 {
  margin: 0;
  font-size: 2rem;
}

.title-block p {
  margin: .2em 0;
  font-size: 1rem;
}

.container {
  display: flex;
  flex-wrap: wrap;
  padding: 1rem;
  justify-content: center;
  background: var(--light-bg);
}

.photo {
  flex: 1 1 250px;
  max-width: 250px;
  padding: 1rem;
}

.photo img {
  width: 100%;
  height: auto;
  border-radius: 8px;
}

.info {
  flex: 2 1 300px;
  padding: 1rem;
  text-align: center;
}

.info h2 {
  margin-top: 0;
  color: var(--primary);
}

nav {
  background: var(--primary);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding: .5rem 0;
}

nav button {
  background: #fff;
  border: 2px solid var(--primary);
  color: var(--primary);
  padding: .5rem 1rem;
  margin: .3rem;
  font-weight: bold;
  border-radius: 5px;
  cursor: pointer;
  transition: background .3s, color .3s;
}

nav button:hover {
  background: var(--primary);
  color: #fff;
}

.nastava-button {
  background: yellow;
  border-color: dark green;
  color: var(--primary);
}

.nastava-button:hover {
  background: #1CBEF8;
  color: #fff;
}

iframe {
  width: 100%;
  height: 80vh;
  border: none;
}

@media (max-width: 768px) {
  body {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
  }

  .main {
    width: 100%;
  }
}

@media (max-width: 480px) {
  nav button {
    flex: 1 1 100%;
  }

  iframe {
    height: 70vh;
  }
}