:root {
  --primary-color: orange;
  --secondary-color: white;
  --theme-primary: black;
  --theme-secondary: white;
}

body {
  font-family: "Segoe UI", "Serif", "Verdana", "Arial";
}

.container {
  display: grid;
  grid-template-columns: 120px 1fr;
  grid-template-rows: 50px 1fr 30px;
  grid-gap: 5px;
}

.header {
  grid-row: 1;
  grid-column: 1 / 3;
}

.nav {
  grid-column: 1;
  grid-row: 2;
  border-right: 1px solid var(--primary-color);
}

.content {
  grid-column: 2;
  grid-row: 2;
  padding: 10px;
}

.footer {
  grid-row: 3;
  grid-column: 1 / 3;
  text-align: center;
}

/* Child items. */
.header-logo {
  float: left;
  width: 100px;
  background-color: var(--primary-color);
  height: 50px;
  color: var(--secondary-color);
  font-size: 30px;
  padding: 3px 5px;
  box-sizing: border-box;
}

.header-settings {
  float: right;
  height: 50px;
}

.nav-links {
  list-style: none;
  margin: 5px 0 0 0;
  padding: 0;
}

.nav-links--link {
  color: var(--primary-color);
  background-color: var(--secondary-color);
  width: 100%;
  height: 30px;
  margin: 0 0 5px 0;
  padding: 4px 5px;
  box-sizing: border-box;
  cursor: pointer;
}

.nav-links--link.active,
.nav-links--link:hover {
  background-color: var(--primary-color);
  color: var(--secondary-color);
}

.footer-note {
  color: var(--primary-color);
  background-color: var(--secondary-color);
  padding: 3px 0;
  display: block;
}

.header--theme-button {
  height: 30px;
  width: 30px;
  margin: 10px 5px 0 0;
  display: inline-block;

  border-top: 15px solid var(--theme-primary);
  border-bottom: 15px solid var(--theme-secondary);
  border-right: 0;
  border-left: 0;
  padding: 0;

  box-shadow: 0 0 3px gray;
}

.header--theme-button:hover {
  box-shadow: 2px 2px 2px gray;
}

.header--theme-button.active {
  box-shadow: 3px 3px 3px gray;
}