.main-section {
  box-sizing: border-box;
  display: flex;
  align-items: center;
  height: 730px;
  overflow: hidden;
}

.main-section.-skills {
  justify-content: center;
  flex-direction: column;
  background-color: #00b4d8;
  border-bottom: 10px #0077b6 solid;
}

.main-section.-project {
  flex-direction: column;
  background-color: #000;
  border-bottom: 10px #00b4d8 solid;
}

.main-section.-about{
  flex-direction: column;
  background-color: #0077b6;
  border-bottom: 10px #000 solid;
  height: 750px;
}

.main-section.-contacts{
  background-color: #3a4756;  
  flex-direction: column;
}

.main-section.-contacts h2{
  margin-bottom: 0px;
}