body {
  margin: 0;
}

.center-container {
  display: flex;
}

.img-container {
  position: relative;
}

.model-btn {
  position: absolute;
  opacity: 0.7;
}

.model-btn:hover,
.model-btn:focus {
  opacity: 1;
}

.img {
  height: 624px;
  width: 912px;
}

.model {
  --border-radius: 10px;
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -70%);
  background-color: white;
  border-radius: var(--border-radius);
  opacity: 0;
  pointer-events: none;
  max-width: 80%;
  font-family: roboto, sans-serif;
  box-shadow: 0 0 100px rgba(0, 0, 0, 0.5);
  transition: 300ms ease-in-out;
}

.model.active {
  opacity: 1;
  transform: translate(-50%, -50%);
  pointer-events: all;
}

.model-header {
  padding: 10px 15px;
  margin-bottom: 10px;
  position: relative;
  display: flex;
  justify-content: space-between;
  border-top-left-radius: var(--border-radius);
  border-top-right-radius: var(--border-radius);
  align-items: center;
  color: black;
  font-weight: bold;
  font-size: 1.1em;
}

.model-header::after {
  --pixels-away-from-edge: 15px;
  content: '';
  position: absolute;
  background-color: rgb(223, 223, 223);
  top: 100%;
  height: 5px;
  left: var(--pixels-away-from-edge);
  right: var(--pixels-away-from-edge);
}

.close-button {
  background-color: transparent;
  color: black;
  border: 0;
  font-size: large;
  font-weight: 900;
  cursor: pointer;
  transition: transform 150ms ease-in-out, 
              color     150ms ease-in-out;
}

.close-button:hover,
.close-button:active {
  transform: scale(1.3);
  color: var(--accent-colour);
}

.model-body {
  padding: 15px;
}

#overlay {
  position: fixed;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
  background-color: rgba(255, 255, 255, 0);
  transition: background-color 300ms ease-in-out;
  pointer-events: none;
}

#overlay.active {
  background-color: rgba(255, 255, 255, 0.5);
  backdrop-filter: blur(5px);
  pointer-events: all;
}

.help-btn {
  position: absolute;
  top: 0;
  left: 0;
  height: 30px;
  width: 30px;
  margin: 10px;
  padding: 0;
  border: 2px solid black;
  border-radius: 50%;
  cursor: pointer;
  background-color: rgba(0, 0, 0, 0);
  font-family: roboto, sans-serif;
  transition: background-color 150ms ease-in-out;
}

.help-btn:hover,
.help-btn:focus {
  background-color: rgba(0, 0, 0, 0.2);
}

@media (min-width: 912px) {
  .center-container {
    justify-content: center;
  }
}