* {
  box-sizing: border-box;
}

html {
  font-family: sans-serif;
  line-height: 1.6;
}

.container {
  display: flex;
  flex-wrap: wrap;
  max-width: 960px;
  margin: auto;
}

.item {
  width: calc(25% - 2em);
  margin: 1em;
  padding: 0 1em;
  background: #eee;
  font-size: .8em;
  flex-grow: 1;
  min-width: 214px;
}
.item__full {
  width: calc(100% - 2em);
  font-size: 1em;
}
.item__half {
  width: calc(50% - 2em);
  flex-shrink: 1;
}

h1, h2, h3, h4, h5, h6 {
  margin: 1rem 0;
  line-height: 1.1;
}