#left-side {
  position: fixed;
  width: 20%;
  padding: 0 10px;
  // background-color: #CCC;
  top: 0;
  left: 0;
  height: 100%;
  overflow-y: auto;
  border-right: 1px solid #FFF;
  box-shadow: 0 0 20px rgba(0,0,0,0.2);
}

#main, #footer {
  margin-left: 20%;
  padding: 15px;
  width: 80%;
}

.row {
  width: 100%;
  box-sizing: border-box;
  display: flex;
  // display: inline-block;
  margin: 10px 0;

  .column {
    // padding: 5px;
    box-sizing: border-box;
    vertical-align: top;
  }

  &.rows-1_2-1_2 {
    .column {
      width: 50%;
    }
  }

  &.rows-1_3-1_3-1_3 {
    .column {
      width: 33.3333%;
    }
  }


  &.rows-2_3-1_3 {
    .column:nth-child(1) {
      width: 66.6666%;
    }
    .column:nth-child(2) {
      width: 33.3333%;
    }
  }

  &.rows-1_3-2_3 {
    .column:nth-child(1) {
      width: 33.3333%;
    }
    .column:nth-child(2) {
      width: 66.6666%;
    }
  }
}


@media only screen and (max-width : #{$extra-large-screen}) {
  #left-side {
    width: 25%;
  }

  #main, #footer {
    margin-left: 25%;
    width: 75%;
  }

}

@media only screen and (max-width : #{$large-screen}) {
  #left-side {
    width: 30%;
  }

  #main, #footer {
    margin-left: 30%;
    width: 70%;
  }

  .row {
    display: block;
    
    &.rows-1_2-1_2,
    &.rows-1_3-1_3-1_3,
    &.rows-2_3-1_3,
    &.rows-1_3-2_3 {
      .column {
        margin: 10px 0;
        width: 100%;

        &:nth-child(1),
        &:nth-child(2) {
          width: 100%;
        }
      }
    }
  }

}

@media only screen and (max-width : #{$medium-screen}) {
  #left-side {
    width: 100%;
    position: relative;
    hr {
      display: none;
    }
    ul {
      display: inline-block;

      li {
        display: inline-block;
        margin: 0 5px;
        &:before {
          display: none;
        }
      }
    }
  }

  #main, #footer {
    margin-left: 10px;
    width: 100%;
  }

}