Admin settings

Everything the toolbar offers is seeded, capped, or made available for editing from Configuration → Content authoring → Canvas Builder (/admin/config/content/canvas-builder, the General tab, a peer of Styles / Components / AI / Blueprints / Usage), behind the Administer Canvas Builder permission. The tab is a vertical-tabs form (GeneralSettingsForm) over the canvas_builder.settings config object, with six sub-tabs:

• Framework: the active profile radio (Custom / Bootstrap 5 / Tailwind) and the Tailwind Safelist viewer. Covered in Frameworks; it's the same page, just a different tab.
• Responsive: which viewports the toolbar's device chip (and the Style panel's device picker) offers, plus each one's label, icon, and the CSS class applied when it's hidden (hide_at_*). Widths themselves are read-only here; they come from Canvas / your theme's {theme}.canvas.yml. Disabling a viewport hides it from the editor but keeps any classes already configured for it. The base (narrowest) viewport can't be disabled: every other viewport's mobile-first cascade inherits from it.

• Sections: layout_maps class-mapping tables for the Section band (width, height, alignment): one framework class per value × viewport, live under a classes engine (Bootstrap/Tailwind), inert under the default css_vars engine. See Frameworks → Layout class maps.
• Columns: the toolbar's actual defaults and caps, plus the Columns family's own layout_maps tables (count, gap, align, column order):

- **Default layout type**: Columns or Grid, applied to every newly
  placed Section.
- **Max columns in editor** (`layout_defaults.columns.max_count`): the
  hard ceiling (1–6) for the toolbar's Structure-tab column-count row and
  the "+ Column" action; every per-viewport **Max allowed** below is
  bounded by it.
- The **per-viewport table** lists **Column default** (the count a new
  Section starts with at that breakpoint), **Max allowed** (`vp_max`, a
  per-viewport ceiling beneath the global max), **Vertical align**,
  **Horizontal align**, and **Gap**: the seed values for `valign`,
  `halign`, and `gap` a freshly placed Section carries before an author
  touches the Arrange/Spacing tabs. Every column past the base viewport
  defaults to **— (inherit)**, matching the mobile-first cascade the
  toolbar itself reads at render/edit time.

• Grid: a pointer note (Grid shares the Columns tab's instance defaults) plus a free-text Grid minimum-item-width list and the Grid family's own layout_maps tables (grid alignment). The toolbar's own Min column width pills (100–400px) come from the Section SDC's fixed prop enum, not from this list.
• Section templates: one table, one row per layout preset (the 12 built-ins, in order, then any custom ones), each with an Enabled checkbox controlling whether it appears in the toolbar's "Choose a column layout" chooser and "More layouts" gallery. Built-in rows are always present and tunable (label locked; Type/Mobile/Tablet/Desktop/Large/Layout ratio editable) but not removable, only turned off. Custom rows add every field including the label, plus a Remove button. A row whose column count exceeds the Columns tab's Max columns in editor value is force-disabled, with the reason shown inline next to its checkbox.