Layout

Cell grid

Each slide has a CSS Grid canvas of nrows × ncols. Cells are placed automatically from left to right, top to bottom.

Use col and row to place a cell at a specific position (1-indexed) instead of the next available slot.

slide = deck.add_slide("Example", nrows=2, ncols=3)

slide.add_text("A")   # row 1, col 1
slide.add_text("B")   # row 1, col 2
slide.add_text("C")   # row 1, col 3
slide.add_text("D")   # row 2, col 1
slide.add_text("E")   # row 2, col 2
slide.add_text("F", row=2, col=3)   # row 2, col 3

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Column widths and row heights

By default the grid distributes space evenly. Use col_widths and row_heights to set explicit sizes using any valid CSS length (px, %, fr, etc.).

slide = deck.add_slide(
    "Custom sizing",
    nrows=2,
    ncols=2,
    col_widths=["2fr", "1fr"],      # left column twice as wide
    row_heights=["120px", "1fr"],   # first row fixed height
)

Mixed units work — fr values fill the remaining space after fixed sizes are applied, the same way they do in native CSS Grid.

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Spanning cells

Use colspan and rowspan to stretch a cell across multiple columns or rows. Use col and row to place a cell at a specific position (1-indexed) instead of the next available slot.

slide = deck.add_slide("Spanning", nrows=2, ncols=3)

# Spans columns 1 and 2 of row 1
slide.add_text("Wide header", colspan=2)

# Column 3, row 1
slide.add_metric(value=42, label="KPI")

# Row 2, spans all 3 columns
slide.add_table({'Col a': [1,2,3], 'Col b': [4,5,6]}, colspan=3)

# Explicit position — column 2, row 1, spanning 2 rows
slide.add_image("photo.png", col=2, row=1, rowspan=2)

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Layout templates

SlideDefaults and CellDefaults can be instantiated independently and passed per-slide via slide_defaults and cell_defaults. This lets you define reusable layout templates and apply them selectively, without changing the global defaults set on Deck.

from montin import Deck, SlideDefaults, CellDefaults

deck = Deck(title="Template Report")

# Define reusable templates
slide_2x2     = SlideDefaults(ncols=2, nrows=2)
slide_2x1     = SlideDefaults(ncols=2, nrows=1)
centered_cell = CellDefaults(halign="center", valign="middle")

# Apply a layout template and a cell template together
s = deck.add_slide("Results", slide_defaults=slide_2x2, cell_defaults=centered_cell)
for i in range(s.nrows * s.ncols):
    s.add_text(f"Cell {i}")

# Apply only a layout template; cell defaults fall back to the global ones
s = deck.add_slide("Summary", slide_defaults=slide_2x1)
for i in range(s.nrows * s.ncols):
    s.add_text(f"Cell {i}")

deck.write("template_report", open_browser=True)

The priority order for each parameter is:

1. Explicit argument — value passed directly to add_slide() or add_*().

2. Per-call default — slide_defaults / cell_defaults argument on add_slide().

3. Global default — slide_defaults / cell_defaults set on Deck.

Use the slide navigator (toggle the sidebar with the ☰ button or B) to compare the centred Results slide with the left-aligned Summary slide.