.client-section {
  width: 100%;
  margin: 0 auto;
  margin-top: 40px;

  @media (min-width: 750px) {
    max-width: 750px;
  }

  .client-logos {
    display: flex;
    justify-content: space-around;
    align-items: center;
    flex-flow: row wrap;

    img {
      width: 40%;
      margin-left: .5em;
      margin-right: .5em;
      filter: grayscale(75%);
      opacity: 0.90;
      transition: all 0.25s ease;
      @media (min-width: 750px) {
        width: 30%;
      }
    }

    img:hover {
      filter: grayscale(20%);
      opacity: 1.00;
    }
  }

}

.client-section {
  width: 100%;
  margin: 0 auto;
  margin-top: 40px;

  @media (min-width: 750px) {
    max-width: 750px;
  }

  .client-logos {
    display: flex;
    justify-content: space-around;
    align-items: center;
    flex-flow: row wrap;

    img {
      width: 40%;
      margin-left: .75em;
      margin-right: .75em;
      filter: grayscale(75%);
      opacity: 0.90;
      transition: all 0.25s ease;
      @media (min-width: 750px) {
        width: 27%;
      }
    }

    img:hover {
      filter: grayscale(20%);
      opacity: 1.00;
    }
  }

}

Adjust width and padding of client logos.
Adjust width and padding of client logos.
