.flex-vertical-center {
  align-items: center;
  display: flex;
}

.margin-top-sm { margin-top: 0.5em; }
.margin-bottom-sm { margin-bottom: 0.5em; }
.margin-left-sm { margin-left: 0.5em; }

.margin-top { margin-top: 1em; }
.margin-right { margin-right: 1em; }
.margin-bottom { margin-bottom: 1em; }
.margin-left { margin-left: 1em; }

.margin-top-x { margin-top: 2em; }

.margin-top-xx { margin-top: 3em; }

.text-center { text-align: center; }

.big { font-size: 1.2em; }
.small { font-size: 0.85em; }

.bold { font-weight: bold; }

.gray { color: #888888; }
.red { color: #ff0000; }