style.css

/* General */
* {
  box-sizing: border-box;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  margin: 0;
  padding: 0;
}

body {
  display: flex;
  flex-direction: row;
  height: 100vh;
}

body > div {
  height: 100%;
}

/* Sidebar */
#sidebar {
  display: flex;
  flex-direction: column;
  max-width: 800px;
  min-width: 300px;
  width: 30%;
}

.sidebar-content {
  padding: 14px;
}

.sidebar-header {
  background-color: #a9a9a9;
  text-align: center;
}

#back-button {
  color: #0000ff;
  text-decoration: underline;
}

#back-button:hover {
  color: #800080;
  cursor: pointer;
}

#event-description {
  background-color: #cccccc;
  flex: 1;
  font-size: 16px;
  text-align: left;
  overflow-y: scroll;
}

#event-description > p, #event-description > figure, #event-description > button.event-list-item {
  margin-bottom: 14px;
}

#event-description > p:last-child, #event-description > figure:last-child, #event-description > button.event-list-item:last-child {
  margin-bottom: 0;
}

#event-description > figure > img {
  display: block;
  width: 100%;
}

#event-description > figure > figcaption {
  font-size: 14px;
  margin-top: 2px;
  text-align: center;
}

#event-description > button.event-list-item {
  background-color: #bababa;
  border: none;
  border-radius: 4px;
  display: block;
  font-size: 22px;
  padding: 8px 10px;
  text-align: left;
  width: 100%;
}

#event-description > button.event-list-item:hover {
  background-color: #a9a9a9;
  cursor: pointer;
}

/* Map */
#map {
  flex: 1;
}