discourse/app/assets/stylesheets/common/base/onebox.scss

a.loading-onebox {
  &:before {
    content: "";
    display: inline-flex;
    float: left;
    margin: 3px 5px 0 0;
    position: relative;
    height: 10px;
    width: 10px;
    border: 2px solid $primary-low-mid;
    border-right-color: transparent;
    border-radius: 50%;
    -webkit-animation: rotate-forever 1s infinite linear;
    animation: rotate-forever 1s infinite linear;
  }
}

.onebox-result {
  @include post-aside;

  margin-top: 15px;
  padding: 12px;
  font-size: $font-0;
  > .source {
    margin-bottom: 12px;
    margin-right: 10px;
    display: block;
    color: $primary;
    position: relative;
    height: 20px;
    .info {
      a {
        color: black;
        text-decoration: none;
        padding-right: 10px;
      }
      position: absolute;
      font-size: $font-0;
      img.favicon {
        margin-right: 3px;
      }
    }
  }

  .onebox-result-body {
    padding-top: 5px;
    img {
      max-height: 80%;
      max-width: 25%;
      height: auto;
      float: left;
      margin-right: 10px;
    }
    h3,
    h4 {
      margin: 0;
    }
    code {
      max-height: 400px;
    }
    .metrics {
      clear: both;
      padding-bottom: 25px;
      .metric {
        display: inline-block;
        padding-left: 33px;
        float: left;
      }
    }
  }
}

// RottenTomatoes Onebox
.onebox-result {
  .onebox-result-body {
    img.verdict {
      float: none;
      margin-right: 7px;
    }
    img.popcorn {
      float: none;
      margin-left: 20px;
      margin-right: 5px;
    }
  }
}

@mixin onebox-favicon($class, $image) {
  &.#{$class} .source {
    background: image-url("favicons/#{$image}.png") no-repeat;
    background-size: 16px 16px;
    padding-left: 20px;
  }
}

aside.onebox {
  border: 5px solid $primary-low;
  margin-bottom: 1em;
  padding: 12px 25px 12px 12px;
  font-size: $font-0;

  header {
    margin-bottom: 8px;
    a[href] {
      color: dark-light-choose($primary-medium, $secondary-medium);
      text-decoration: none;
    }
  }

  @include onebox-favicon("stackexchange", "stackexchange");
  @include onebox-favicon("twitterstatus", "twitter");
  @include onebox-favicon("wikipedia", "wikipedia");
  @include onebox-favicon("githubblob", "github");
  @include onebox-favicon("githubcommit", "github");
  @include onebox-favicon("githubpullrequest", "github");
  @include onebox-favicon("githubissue", "github");
  @include onebox-favicon("githubgist", "github");
  @include onebox-favicon("amazon", "amazon");
  @include onebox-favicon("instagram", "instagram");
  @include onebox-favicon("googledocs", "google_branding/logo_drive_48px");

  .onebox-body {
    clear: both;

    h3,
    h4 {
      font-size: $font-up-1;
      margin: 0 0 10px 0;
    }

    a[href] {
      color: dark-light-choose($tertiary, $tertiary);
      text-decoration: none;
    }

    a[href]:visited {
      color: dark-light-choose($tertiary, $tertiary);
    }

    img {
      max-height: 170px;
      max-width: 20%;
      @media all and (max-width: 600px) {
        max-width: 35%;
      }
      height: auto;
      width: auto;
      float: left;
      margin-right: 10px;
      &.onebox-full-image {
        max-height: none;
        max-width: none;
        width: initial;
        height: initial;
      }
    }

    [style*="--aspect-ratio"] > :first-child {
      width: 100%;
    }
    [style*="--aspect-ratio"] > img {
      height: auto;
    }

    // this allows us to load all onebox images without jiggle
    // see: http://cssmojo.com/aspect-ratio-using-custom-properties-and-calc/
    @supports (--custom: property) {
      .aspect-image {
        max-height: 170px;
        --magic-ratio: calc(var(--aspect-ratio) + 0.15);
        width: calc(128px * var(--magic-ratio));
        max-width: 20%;
        float: left;
        margin-right: 10px;
        height: auto;

        img {
          width: 100%;
          height: inherit;
          max-width: initial;
          max-height: initial;
          float: none;
          margin-right: none;
        }
      }

      // full size images for instagram, twitter, etc.
      .aspect-image-full-size {
        max-height: 500px;
        width: calc(500px * var(--aspect-ratio));
        max-width: 100%;

        img {
          width: 100%;
          height: inherit;
          max-width: initial;
          max-height: initial;
          float: none;
          padding: 5px 5px 5px 5px;
        }
      }

      [style*="--aspect-ratio"] {
        position: relative;
      }
      [style*="--aspect-ratio"]::before {
        content: "";
        display: block;
        padding-bottom: calc(100% / (var(--aspect-ratio)));
      }
      [style*="--aspect-ratio"] > :first-child {
        position: absolute;
        top: 0;
        left: 0;
        height: 100%;
      }
    }

    // tighten bottom margin on last para
    p:last-child {
      margin-bottom: 4px;
    }

    // twitter fixes
    .tweet-images {
      display: block;
      clear: both;

      img.tweet-image {
        margin-top: 1em;
        max-width: 100%;
        max-height: 100%;
        float: none;
      }
    }

    &.user-onebox {
      .fa {
        margin-right: 5px;
      }
      .full-name,
      .location {
        margin-right: 10px;
      }
    }

    // instagram + reddit fixes
    .instagram-images,
    .scale-images {
      clear: both;
      position: relative;

      .instagram-video-icon {
        &:before {
          opacity: 0.8;
          // ideally, the SVG used here should be in HTML and reference the SVG sprite
          content: svg-uri(
            '<svg xmlns="http://www.w3.org/2000/svg" width="32px" height="32px" viewBox="0 0 512 512" fill="white"><path d="M424.4 214.7L72.4 6.6C43.8-10.3 0 6.1 0 47.9V464c0 37.5 40.7 60.1 72.4 41.3l352-208c31.4-18.5 31.5-64.1 0-82.6z"></path></svg>'
          );
        }
        bottom: 10px;
        right: 10px;
        position: absolute;
      }

      .instagram-image,
      .scale-image {
        padding: 5px 5px 5px 5px;
        max-width: 100%;
        max-height: 100%;
        float: none;
      }
    }
  }
}

@mixin gdocs-logo($type) {
  &.g-#{$type}-logo {
    background: image-url("favicons/google_branding/logo_#{$type}_48px.png")
      no-repeat;
  }
}

.googledocs-onebox-logo {
  width: 60px;
  height: 50px;
  float: left;
  @include gdocs-logo("docs");
  @include gdocs-logo("forms");
  @include gdocs-logo("sheets");
  @include gdocs-logo("slides");
  @include gdocs-logo("calendar");
  @include gdocs-logo("drive");
}

// Google Calendar Placeholder
.gdocs-onebox-splash {
  background-color: blend-primary-secondary(30%);
  color: $primary;
  border: 1px inset $primary;
  .gdocs-onebox-logo {
    display: inline-block;
    width: 128px;
    height: 128px;
    &.g-calendar-logo {
      background: image-url("favicons/google_branding/logo_calendar_128px.png")
        no-repeat;
    }
  }
}

aside.onebox .onebox-body .onebox-avatar {
  max-height: none;
  max-width: none;
  height: 60px;
  width: 60px;
}

blockquote {
  aside.onebox {
    @include post-aside;
  }
}

// -- Onebox Github Code Blob --
pre.onebox code ol.lines li:before {
  position: absolute;
  display: inline-block;
  width: 35px;
  left: -40px;
  color: #afafaf;
  text-align: right;
  padding-right: 5px;
  font-size: $font-down-1;
  line-height: $line-height-large;
  content: counter(li-counter);
  counter-increment: li-counter;
}

pre.onebox code ol {
  margin-left: 0;
  line-height: $line-height-large;
}
pre.onebox code {
  background-color: dark-light-choose(#fff, #000);
}
pre.onebox code li {
  padding-left: 5px;
}

pre.onebox code ol.lines {
  position: relative;
  margin: 0 0 0 40px;
}

pre.onebox code ol.lines li {
  list-style-type: none;
  padding-left: 5px;
  margin-left: 0;
  border-left: 1px solid #cfcfcf;
  min-height: 1.5em; //show empty li lines
  white-space: pre;
}

pre.onebox code li.selected {
  background-color: dark-light-choose(#f8eec7, #541);
}

pre.onebox code {
  white-space: normal;
}

//Onebox - Github - Pull request
.onebox-body .github-commit-status {
  background: #f5f5f5;
  border-radius: 5px;
  margin: 0 0 5px 100px;
  padding: 10px;
}

.onebox-body .status_tag {
  display: inline-block;
  color: #fff;
  padding: 1px 4px;
  border-radius: 3px;
  font-weight: bold;
  margin-bottom: 5px;
  text-transform: capitalize;
}

.onebox-body .build_status {
  padding: 2px;
  font-size: $font-down-1;
}

.onebox-body .status_tag.open {
  background-color: #6cc644;
}
.onebox-body .status_tag.merged {
  background-color: #6e5494;
}
.onebox-body .status_tag.closed {
  background-color: #bd2c00;
}

.onebox-body .github-content-right {
  margin-left: 100px;
}

//Onebox - Twitter - Status
aside.onebox.twitterstatus .onebox-body {
  h4 {
    margin-bottom: 0;
  }
}

// thumbnail, oddly, ONLY applies to twitter avatar
.onebox.twitterstatus {
  .thumbnail {
    width: 48px;
    height: 48px;
  }
  p,
  .tweet {
    white-space: pre-wrap;
    padding-top: 3px;
    margin-left: 70px;
  }
  .date {
    clear: left;
    padding-top: 10px;
  }
}

// Onebox - Imgur - Album
.onebox.imgur-album {
  .outer-box {
    position: absolute;
    z-index: z("base");
    overflow: hidden;
    font-size: $font-down-1;
    color: #fff;
    background-color: rgba(0, 0, 0, 0.6);
    text-overflow: ellipsis;
    max-width: 100%;
    padding: 5px 0;

    .inner-box {
      padding-left: 10px;
      padding-right: 10px;
      overflow: hidden;
      text-overflow: ellipsis;
      word-wrap: normal;
      white-space: nowrap;

      .album-title {
        width: 100%;
        font-size: $font-up-1;
        line-height: $line-height-large;
        color: #ccc;
        text-decoration: none;
      }
    }
  }
}

// resize stackexchange onebox image
aside.onebox.stackexchange .onebox-body {
  img:not(.onebox-avatar) {
    max-height: 60%;
    max-width: 10%;
  }

  .tags {
    color: gray;
  }
}

.onebox-metadata {
  color: dark-light-choose($primary-medium, $secondary-medium);
}

.onebox.xkcd .onebox-body {
  img {
    max-width: 100% !important;
    float: none !important;
  }
}

// pdf onebox
.onebox.pdf .onebox-body {
  .pdf-onebox-logo {
    width: 60px;
    height: 50px;
    float: left;
    background: image-url("favicons/pdf_64px.png") no-repeat;
    background-size: 48px 48px;
    display: inline-block;
  }
  .filesize {
    color: gray;
  }
}

// whitelistedgeneric twitter labels
.onebox.whitelistedgeneric {
  .label1,
  .label2 {
    color: dark-light-choose($primary-medium, $secondary-medium);
  }
  .label1 {
    float: left;
  }
  .label2 {
    float: right;
  }
}

.onebox {
  &.whitelistedgeneric,
  &.gfycat {
    .site-icon {
      width: 16px;
      height: 16px;
      margin-right: 3px;
    }
  }
}

.onebox.gfycat p {
  span.label1 a {
    white-space: nowrap;
  }
}

.onebox.instagram {
  div.instagram-description {
    color: dark-light-choose($primary-medium, $secondary-medium);
    padding-top: 10px;
  }
}

.onebox.githubcommit {
  pre.message {
    padding: 0;
  }
}

.onebox.twitterstatus {
  .like,
  .retweet {
    color: dark-light-choose($primary-medium, $secondary-medium);
    padding-left: 10px;
    svg {
      fill: currentColor;
      vertical-align: middle;
    }
  }
}

// mobile specific style
.mobile-view article.onebox-body {
  border-top: none;
}

// Google Photos Album
.onebox.google-photos-album {
  @extend .imgur-album;
}

// Force oneboxed videos to 16:9 aspect ratio
.onebox.video-onebox {
  position: relative;
  padding: 0 0 56.25% 0;
  width: 100%;

  video {
    position: absolute;
    width: 100%;
    height: 100%;
  }
}