discourse/app/assets/stylesheets/mobile/compose.scss

.composer-popup-container {
  display: none !important; // can be removed if inline JS CSS is removed from composer-popup
}

.composer-popup {
  display: none !important; // can be removed if inline JS CSS is removed from composer-popup
}

#reply-control {
  z-index: z("mobile-composer");
    .reply-area {
      padding: 0 10px;
      @media screen and (max-width: 374px) {
        padding: 0 5px;
      }
      flex-grow: 1;
    }

    &.open {
      height: 250px;
      &.edit-title {
        height: 100%;
      }
    }

    .reply-to {
      margin: 5px 0;
    }

    .toggler {
      margin-left: -5px;
      .d-icon-chevron-down {
        vertical-align: text-top;
      }
    }

    &.draft {
      .toggle-toolbar,
      .toggler {
        top: 8px;
      }
      .draft-text {
        width: calc(100% - 40px);
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
      }
    }

    #reply-title {
      width: calc(100% - 20px);
    }

    .category-input {
      margin-bottom: 5px;
      .category-chooser {
        width: 100% !important;
      }
    }

    .submit-panel {
      margin-bottom: 5px;
      align-items: baseline;
      .save-or-cancel {
        flex: 1 1 auto;
        #draft-status,
        #file-uploading {
          margin-left: 15px;
        }
        .cancel {
          font-size: 1.6em;
          color: $primary-low-mid;
          margin-left: .6em;  
          padding: 0 5px;        
        }
      }
      .composer-bottom-right {
        margin-left: auto;
        flex: 1 1 auto;
      }
    }

    .d-editor-textarea-wrapper {
      width: 100%;
    }

    &.show-preview {
      .d-editor-preview-wrapper {
        position: fixed;
        z-index: z("base") + 1;
        top: 0;
        bottom: 0;
        left: 0;
        right: 0;
        background-color: $secondary;
        max-width: 100%;
        margin: 0;
        padding: 10px;
        overflow: auto;        
        .d-editor-preview {
          margin-bottom: 40px;
        }
      }
      .btn.hide-preview {
        position: fixed;
        right: 5px;
        bottom: 5px;
        z-index: z("base") + 2;
      }
    }

    &.hide-preview {
      .d-editor-preview-wrapper {
        display: none;
      }
    }

    .d-editor-button-bar {
      display: none;
    }

    .toolbar-visible .d-editor-button-bar {
      display: flex;
    }

    .d-editor-button-bar .btn {
      @media all and ( max-width: 350px) {
        padding: 2px 4px;
      }
      &.preview {
        margin: 0;
      }
    }

    #mobile-uploader {
      display: none;
    }

    .title-and-category,
    .user-selector {
      margin: 0;
      .users-input {
        margin-bottom: 5px;
      }
    }

    .title-input,
    .category-input,
    .users-input,
    .add-warning {
      width: 100%;
    }

    .add-warning {
      margin: 0 0 5px 5px;
    }
  }