[BUG] dash_table.DataTable styling issues for header height and column width when using fixed_columns

Context

• dash: 3.0.4
• OS: Windows
• Browser: Firefox 139.0.4

Bug description

I have data where the column name is longer than the data itself. When putting the column as fixed_column in a DataTable, the width of the displayed column seems to be calculated disregarding the length of the column name.

from dash import Dash, dash_table
import pandas as pd

df = pd.DataFrame(
    {
        "longer header": ["aaaaaa", "bbbbbb", "cccccc"],
        **{f"column {i}": ["12345", "12345", "12345"] for i in range(1, 10)},
    }
)

app = Dash()
app.layout = dash_table.DataTable(
    data=df.to_dict("records"),
    columns=[{"id": c, "name": c} for c in df.columns],
    fixed_columns={"headers": True, "data": 1},
    style_table={"minWidth": "100%"},
)

if __name__ == "__main__":
    app.run(debug=True)

If I remove the fixed_columns attribute, it works fine:

Additionally, if I add line breaks to the fixed column header, the height of the header is mismatched between the fixed and the non-fixed columns.

from dash import Dash, dash_table
import pandas as pd


df = pd.DataFrame(
    {
        "longer\nheader": ["aaaaaa", "bbbbbb", "cccccc"],
        **{f"column {i}": ["12345", "12345", "12345"] for i in range(1, 10)},
    }
)

app = Dash()
app.layout = dash_table.DataTable(
    data=df.to_dict("records"),
    columns=[{"id": c, "name": c} for c in df.columns],
    fixed_columns={"headers": True, "data": 1},
    style_table={"minWidth": "100%"},
    style_cell={"whiteSpace": "pre-line"},
)

if __name__ == "__main__":
    app.run(debug=True)

Again this is does not occur if the fixed_columns attribute is removed:

Expected behavior

The width of a fixed column in a DataTable is calculated taking into account the column name as well as the data. The height of the header row of the DataTable is calculated taking into account fixed and non-fixed columns.

Inizia eseguendo le riproduzioni fornite di Dash e pandas, prima con fixed_columns e poi senza, incluso il caso di intestazione multilinea. Traccia il comportamento di stile e dimensionamento delle colonne bloccate di DataTable; il lavoro è completato quando la larghezza della colonna bloccata include il testo dell’intestazione e le altezze delle intestazioni bloccata e non bloccata corrispondono.