The Graph Builder makes Excel workbooks whose charts are native Excel charts linked to Excel Tables, not pictures. Change a number in Excel and the chart redraws; type a new row under a table and the chart grows to include it.
Each chart gets its own sheet. Blue cells are inputs; shaded columns are formulas that prepare the chart (for example the invisible base of a bridge), so leave them in place. To remove data, right-click inside a table and choose Delete, Table Rows. Chart titles are linked to cell A1 of each sheet.
Pick a style at the top of the page and every chart follows it: Default for the scottishpawel look, Boardroom for executive packs and Dark for screens. Colours adapt to each style. A chart can keep its own style from its Style tab, and any colour you pick yourself stays the same in every style.
Everything happens in your browser. Your data is not uploaded anywhere; your workbook list is kept only in this browser's storage so it survives a refresh.
The self-test builds a workbook with awkward sheet and column names and checks its structure.