.flex-container {
  display: flex;
  align-items: flex-start;
}

aside {
  margin-left: 30px;
  flex-grow: 1;
}
.main-section {
  flex-grow: 3;
}

.main-section p {
  min-height: 260px;
}

aside .event-item {
  margin-bottom: 15px;
}

aside .event-details {
  border-left: 5px solid #009690;
  background-color: #e5f4f3;
  padding: 5px 8px;
}

aside .event-date {
  display: inline-block;
  margin: 5px 0;
  font-size: 85%;
}
aside .event-title {
  font-weight: bold;
}

aside .event-register > a {
  display: inline-block;
  border-radius: 10px;
  background-color: #009690;
  color: #ffffff;
  font-size: 85%;
  padding: 2px 8px;
  margin: 5px 0px;
}

aside .event-register > a:active,
aside .event-register > a:visited {
  color: #fff;
}

aside .event-register > a:hover {
  color: #ddd;
  cursor: pointer;
}

.cert {
  float: right;
  width: 120px;
  margin: 0 0 18px 15px;
}

.cert figure figcaption {
  margin-top: 8px;
  line-height: 1.2;
  font-size: 80%;
  font-style: oblique;
}

@media screen and (max-width: 768px) {
  .flex-container {
    display: block;
  }

  .main-section {
    display: block;
  }

  aside {
    margin-left: 0;
    margin: 0 10px;
    display: grid;
    grid-template-columns: auto auto;
    grid-gap: 50px;
  }
}