[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.

Start by running the provided Dash and pandas reproductions, first with fixed_columns and then without it, including the multiline header case. Trace the DataTable fixed-column styling and sizing behavior; done when fixed-column width includes the header text and the fixed and non-fixed header heights match.