<ul class="portfolio">

      <li class="repo">
        <a href="#">Repo name</a>
      </li>

      <li class="repo">
        <a href="#">Repo name</a>
      </li>

      <li class="repo">
        <a href="#">Repo name</a>
      </li>

      <li class="repo">
        <a href="#">Repo name</a>
      </li>

      <li class="repo">
        <a href="#">Repo name</a>
      </li>

      <li class="repo">
        <a href="#">Repo name</a>
      </li>

      
</ul>
        
      
        
body {
    margin: 0;
    font-size: 15px;
    line-height: 1.6;
    font-family: 'Montserrat', sans-serif;
    font-weight: 400;
    color: #3A3A3A;
}

* {
    box-sizing: border-box;
}

.portfolio {
    list-style: none;
    padding: 0;
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    width: 90%;
    max-width: 1200px;
    &:hover {
        .repo {
            opacity: 0.5;
            &:hover {
                opacity: 1;
            }
        }
    }
}

.repo {
    position: relative;
    display: block;
    width: 32.33%;
    margin: .5%;
    padding: 30px 30px;
    background: #f4f4f4;
    transition: .2s;
    @media (max-width: 960px) {
        width: 49%;
    }
    &:nth-of-type(3n) {
        border-right: 0;
    }
    a {
        text-decoration: none;
    }
}

External CSS

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External JavaScript

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