.sidebar {
  position: absolute;
  z-index: 2;
  background-color: rgba(#25282A, .97);
  color: white;
  min-width: 20rem;
  width: 25%;
  top: 10px;
  bottom: 10px;
  left: 10px;
  overflow: auto;
  box-shadow: 0 0 .5rem rgba(#25282A, .25);
  border-radius: .2rem;

  &-content {
    padding: 1.25rem;

    p:last-child {
      margin: 0;
    }
  }

  &-header,
  &-footer {
    padding: 1.25rem;
    position: relative;
    text-align: center;

    h1,
    h2,
    h3,
    h4,
    h5,
    p {
      margin: 0;
    }
  }

  &-header {

      &-row {
        display: table;
      }
      &-col {
        display: table-cell;
        vertical-align: middle;

        &-expand {
          width: 99%;
        }
      }

      &-nav {

        &-link {
          // margin-right: 1.5rem;

          &,
          &:hover,
          &:focus {
            color: inherit;
            text-decoration: none;
            opacity: .75;
          }

          &:hover,
          &:focus {
            opacity: 1;
          }
        }
      }
  }

  &-footer {
    font-size: .8em;
  }
}

.sidebar {
  position: absolute;
  z-index: 2;
  background-color: rgba(#25282A, .97);
  color: white;
  min-width: 20rem;
  width: 25%;
  top: 10px;
  bottom: 10px;
  left: 10px;
  overflow: auto;
  box-shadow: 0 0 .5rem rgba(#25282A, .25);
  border-radius: .2rem;

  &-content {
    padding: 1.25rem;

    p:last-child {
      margin: 0;
    }
  }

  &-header,
  &-footer {
    position: relative;

    h1,
    h2,
    h3,
    h4,
    h5,
    p {
      margin: 0;
    }
  }

  &-header {

      &-row {
        display: table;
        border-spacing: 1.25rem;
      }
      &-col {
        display: table-cell;
        vertical-align: middle;

        &-expand {
          width: 99%;
        }
      }

      &-nav {

        &-link {

          &,
          &:hover,
          &:focus {
            color: inherit;
            text-decoration: none;
            opacity: .75;
          }

          &:hover,
          &:focus {
            opacity: 1;
          }
        }
      }
  }

  &-footer {
    font-size: .8em;
    padding: 1.25rem;
    text-align: center;
  }
}

Change <SidebarHeader /> align and spacing
Change <SidebarHeader /> align and spacing
