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

// 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 {
  top: 50%;
  left: 50%;
  width: 610px;
  margin: -250px 0 0 -305px;
  .cancel {
    margin-left: 1em;
  }
}

.modal.in {
  -webkit-animation: fade 0.25s;
  animation: fade 0.25s;
}

.modal-body {
  padding: 15px;
}

.modal-footer .btn.right {
  float: right;
}

.modal-header {
  h3 {
    font-size: $font-up-3;
  }
}

.close {
  font-size: $font-up-3;
  text-decoration: none;
  &:visited {
    color: $primary-high;
  }
  cursor: pointer;
  &:hover {
    color: $primary;
  }
}

.modal {
  .category-chooser {
    width: 50%;
  }
}

.edit-category-modal {
  .modal-body {
    position: relative;
    height: 420px;
  }

  .disable_info_wrap {
    .cannot_delete_reason {
      top: -100px;
      right: 4px;
      max-width: 380px;
      min-width: 300px;
    }
  }
}

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

  .bulk-buttons {
    display: flex;
    flex-wrap: wrap;
    margin-right: -1%;

    .btn {
      flex: 1 0 30%;
      margin-bottom: 1em;
      margin-right: 1%;
      white-space: nowrap;
      overflow: hidden;
      max-width: 33%;

      @media screen and (max-width: 767px) {
        flex: 1 0 48%;
        max-width: 48%;
      }

      @include breakpoint(mobile) {
        flex: 1 1 auto;
        min-width: 49%;
        max-width: unset;
      }
    }
  }
}

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

  #move-selected {
    // prevents content from moving when user selects different move options 525px
    // is the same width we set on category edit modal
    width: 525px;

    p {
      margin-top: 0;
    }

    .radios {
      margin-bottom: 10px;
      display: flex;
      flex-direction: row;

      .radio-label {
        display: inline-block;
        padding-right: 15px;
      }
    }

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

    .category-chooser {
      margin-bottom: 9px;
    }

    form {
      width: 95%;
      margin-top: 20px;
      #split-topic-name,
      #choose-topic-title,
      #choose-message-title {
        width: 100%;
      }

      .participant-selector {
        width: 100%;
      }

      div.ac-wrap {
        width: 100%;
        margin-bottom: 9px;
      }
    }
  }
}