discourse/app/assets/stylesheets/desktop/modal.scss

// base styles for every modal popup used in Discourse

.modal-middle-container {
  display:table-cell;
  vertical-align: middle;
}

// Hardcode to be the same as before for now. I would recommend not using bootbox, or finding a way so the html structure can be the same
.bootbox.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  z-index: 1050;
  overflow: auto;
  width: 610px;
  height: auto;
  margin: -250px 0 0 -305px;
  background-color: $primary_background_color;
  border: 1px solid $primary_border_color;
  border: 1px solid lighten($primary_border_color, 10%);

  box-shadow: 0 3px 7px rgba($primary_shadow_color, .8);
  background-clip: padding-box;

}

.modal.in {
-webkit-animation: modal .25s;
animation: modal .25s;
}

//fade in and animate up

@-webkit-keyframes modal {
    from {opacity: 0}
    to {opacity: 1}
}@keyframes fade {
    from {opacity: 0}
    to {opacity: 1}
}

.modal-body {
  overflow-y: auto;
  max-height: 400px;
  padding: 15px;
}

.modal-footer .btn + .btn {
  margin-left: 5px;
  margin-bottom: 0;
}
.modal-footer .btn.right {
  float: right;
}

.modal-footer .btn-group .btn + .btn {
  margin-left: -1px;
}
.modal-header {
  border-bottom: 1px solid $primary_border_color;
  h3 {
    color: $nav-pills-background-color-active;
    font-size: 20px;
    padding: 10px 15px 7px;
  }
  .close {
    float: right;
    font-size: 20px;
    margin: 10px 10px 0;
    text-decoration: none;
    color: $modal-close-button-color;
    cursor: pointer;
    &:hover {
      color: darken($modal-close-button-color,20);
    }
  }
}

.modal {
  .category-combobox {
    width: 430px;

    .chzn-drop {
      left: -9000px;
      width: 428px;
    }
    .chzn-search input {
      width: 378px;
    }

    .chzn-search-icon {
      margin-top: 8px;
    }
  }
}

.flag-modal {
  max-height: 450px;
}

.custom-message-length {
  margin-bottom: 10px;
  margin-left: 20px;
}

.flag-message {
  margin-left: 20px;
  width: 95% !important;
}

.edit-category-modal {
  .modal-body {
    position: relative;
    height: 420px;
    max-height: 420px;
    padding-bottom: 0;
  }
  .secure-category-options {
    margin: 10px 0 0 16px;
    .badge-list {
      margin: 10px 0;
      li {
        margin: 0 4px 8px 0;
        a {
          color: lighten($primary_text_color, 50%);
          cursor: pointer;
        }
        a:hover {
          color: $primary_text_color;
        }
      }
    }
  }
}

.topic-bulk-actions-modal {
  p {
    margin-top: 0;
  }
  &.full .modal-body {
    height: 400px;
    max-height: 400px;
  }
}
.tabbed-modal {
  .modal-body {
    position: relative;
    height: 350px;
  }
}

.modal-tab {
  position: absolute;
}

.split-modal {
  .modal-body {
    position: relative;
    height: 350px;
  }

  #move-selected {
    p {
      margin-top: 0;
    }

    input[type=radio] {
      margin-right: 10px;
    }

    button {
      margin-top: 10px;
      display: block;
      width: 300px;
    }

    form {
      margin-top: 20px;
      #split-topic-name, #choose-topic-title {
        width: 520px;
      }
    }
  }
}