You can use flexbox layout.
override the ui-panel-content class to use flex properties:
.ui-panel-content { padding: 0 !important; display: flex; justify-content: space-between;
Here is your HTML content for your panel:
<div class="panelContent"> <textarea [rows]="5" [cols]="30" pInputTextarea autoResize="autoResize"></textarea> </div> <div class="panelBorder"></div>
and the corresponding CSS:
.panelContent { padding:5px; } .panelBorder { background: red; width: 4px; }
See Plunker
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