# HUST Beamer visual system

This file is the design contract for `v0.7`. New templates and components
should extend these rules instead of introducing page-specific geometry.

## Design direction

The theme combines Moloch's presentation mechanics with a HUST-specific visual
language:

- Oxford-like whitespace and single-focus section dividers
- ETH-like grid discipline and restrained recurring identity
- CUHK-like Chinese/English metadata handling
- Split-band boxes with a restrained serif callout voice
- THU-like separation of theme, color, font, inner, and outer concerns
- Copenhagen-like readiness for unit-level variants

The result is not a permanent branded sidebar. HUST identity is concentrated
where it carries meaning and is absent from ordinary-page footers.

## Page geometry

- Canvas: `160 × 90 mm` (`aspectratio=169`)
- Physical safe margin for branded and special pages: `10 mm`
- Ordinary title field: `x = 12 mm`, width `136 mm`
- Ordinary body field: `x = 17 mm`, width `115 mm`
- Logical grid: 12 columns of `8 mm` with `4 mm` gutters
- Header label top: `4.8 mm`
- Page title top: `10.2 mm`
- No decorative rule below the title
- Header reservation: `0–21 mm`
- Main content region: approximately `24–78 mm`
- Footer region: `81–86 mm`

Recommended fixed-width column splits inside the `115 mm` body field:

| Split | Widths |
| --- | --- |
| Wide + narrow | `78 mm + 32 mm` |
| Balanced asymmetric | `66 mm + 44 mm` |
| Equal thirds | `35 mm + 35 mm + 35 mm` |

Do not restore a permanent right rail. An asymmetric content split is chosen
per slide and must stay inside the inset body field.

## Page families

### Cover

- Full-height `60 mm` deep structural-blue identity field (`37.5%` of the
  canvas)
- Emblem, inverse Chinese standard name, and bilingual unit lockup in the field
- Quiet HUST-paper content field from `x = 60–160 mm`
- Event, title, and subtitle share the `x = 70 mm` anchor
- Author and date close the identity field at its lower edge
- Main title measure: `80 mm`, set in HUST ink rather than inverse white
- An optional photograph may replace the blue field base under an `88%` blue
  overlay; it never changes the text geometry
- Main title limited to one or two lines
- English subtitle is secondary and may use up to two lines

The cover is the strongest identity moment, but blue remains below half of the
canvas. This left-field composition must not recur on ordinary content pages.

### Outline

- White canvas and full `140 mm` information width
- One short, single-line `HUSTInk` title, then open blue-numbered rows
- No cards, rail, or repeated emblem
- Page-number-only light footer

### Section divider

- Full `HUSTFrameBlue` canvas
- White inverse wordmark at top left
- Small chapter label, one large section title, and one optional claim
- Physical page number at bottom right

### Standard content

- Section label: `8.5 pt / 10.5 pt`, bold, `HUSTFrameBlueSoft`
- Page title: `13.5 pt / 17 pt`, bold, `HUSTInk`
- The label and title use fixed slots at `4.8` and `10.2 mm`
- Keep ordinary titles to one line when possible and never exceed two lines
- Ordinary frames do not render `\framesubtitle`; place any supporting claim
  in the body hierarchy instead
- A reserved `21 mm` title field keeps body baselines stable across the deck
- Whitespace closes the title field; ordinary frames have no decorative rule
- Body starts at `x = 17 mm`, creating a `5 mm` step from the title anchor
- Body width is `115 mm` (`71.875%` of the canvas); do not stretch sparse
  content to the right edge
- No wordmark, unit name, or other metadata at bottom left
- Physical page count at bottom right

### Closing

- Full `HUSTFrameBlue` canvas
- Same inverse brand and page anchors as section dividers
- One large closing message, English prompt, and compact author/unit detail

## Color semantics

> **Hard rule: `HUSTFrameBlue` belongs to the page skeleton. The separate box
> blue and pink are controlled component accents and may appear only in native
> box title bands.**

| Token | Role |
| --- | --- |
| `HUSTBlue` | Official reference blue; external identity assets and compatibility |
| `HUSTFrameBlue` | Deep structural blue for pagination and full brand pages |
| `HUSTFrameBlueSoft` | Slightly lighter structural label |
| `HUSTFrameRule` | Quiet separator inside structural metadata |
| `HUSTRed` | Alerts, failure, corrective feedback |
| `HUSTInk` | Ordinary page titles, body headings, metrics, and strong content |
| `HUSTText` | Ordinary body text |
| `HUSTMuted` | Supporting text and metadata |
| `HUSTRule` | Neutral content dividers and borders |
| `HUSTMist` | Default neutral information surface |
| `HUSTSurfaceStrong` | Stronger neutral grouping surface |
| `HUSTBluePale` | Inverse supporting text on blue brand pages only |
| `HUSTCode` | Code surface |
| `HUSTBoxBlue` | Primary box title band only |
| `HUSTBoxBlueWash` | Nearly neutral body surface under a blue title band |
| `HUSTBoxPink` | Definition, formula, evidence, or secondary box title band |
| `HUSTBoxPinkWash` | Pale warm body surface under a pink title band |
| `HUSTBoxGold` | First-level list marker inside blue and pink boxes only |
| `HUSTAlertDeep` | Accessible small alert title and marker on pink |

The page-blue allowlist is deliberately short: frame label, page number,
outline navigation, and the cover/section/closing fields. `HUSTBoxBlue` is not
page blue and cannot be reused outside a native box title band.
Ordinary page titles, body headings, kickers, metrics, formulas, open-list
markers, table values, code keywords, and self-authored diagram nodes or
arrows must default to `HUSTInk`, `HUSTText`, `HUSTMuted`, or a neutral
surface. Native box title bands are the explicit exception.

Body emphasis is created with weight, scale, whitespace, and placement, never
by borrowing page blue. `HUSTBluePale` is prohibited on ordinary content
pages. A data visualization may define its own categorical palette, but
neither `HUSTFrameBlue` nor `HUSTBoxBlue` may become its automatic first
series.

Pink is not alert red. Red is not a general decoration color: a normal slide
should have no red focus, while a diagram may use one red corrective path.

## Component grammar

### Items

- Native `itemize` and `enumerate` are the default list interfaces
- Unordered lists use circular bullets at every level; size and gray value,
  rather than a change of shape, communicate nesting
- Ordered lists use `01`, `02`, `03` at the first level, then `a`, `b` and
  `i`, `ii` for nested levels
- First-level items receive `1.25 mm` separation; nested lists become tighter
- `\hustitem{title}{note}` is the preferred pattern when an item needs a bold
  claim and one muted supporting line
- Prefer no more than four first-level items and two visible levels per slide;
  the third level exists for compatibility, not as a default composition
- Open-list markers remain neutral content and never borrow structural brand
  blue; a box may locally use `HUSTBoxGold` at the first level

### Boxes

- Native `block`, `exampleblock`, and `alertblock` are the public interfaces
- `block` uses a `HUSTBoxBlue` title band for a primary explanation,
  comparison, summary, conclusion, or future-work region
- `exampleblock` uses a `HUSTBoxPink` title band for a definition, formula,
  model, evidence region, or secondary emphasis
- `alertblock` keeps the pink anatomy but uses a red title and first-level
  marker only for a real warning, limitation, or failure
- Every box joins a colored title band directly to its pale body field, with
  square corners, no shadow, no border, and no gap between the two surfaces
- The title band uses approximately `1.4 mm` horizontal inset; the body uses
  `2.4 mm` padding
- Box title and body use a restrained Roman/Song voice at `9.5/12 pt` and
  `9.2/13 pt`; running content outside boxes stays sans serif
- A slide normally uses one primary box or two related compact boxes; a double
  box should keep each body to two or three short items
- Blue and pink are selected by meaning, never alternated as decoration, and
  ordinary list items must not be converted into separate boxes

Metrics are open black typography by default. Numbered principles and
conclusions use open rows. A filled surface is justified only when it groups
related content or separates code/data from the page.

Chinese carries the primary message. English is supporting metadata and uses a
smaller, consistent secondary style. Repeating the full bilingual school or
unit name on every page is prohibited.

## Information-density rules

- One dominant claim or composition per slide
- Prefer two purposeful regions over three unrelated cards
- Keep ordinary body text near `9.5 pt / 13.5 pt`
- Keep a single box to three or four short items; keep each box in a stacked
  pair to two or three short items
- Never stack three colored title bands on one ordinary slide
- Keep titles short enough for one line whenever possible
- Use the `78 + 32 mm` split for dense tables with a narrow metric column
- Give diagrams the full `115 mm` body width when possible
- Reserve at least one clear whitespace region; do not fill the canvas merely
  to make it look substantial

## Review checklist

- Does the slide preserve the `12 mm` title anchor and `17 mm` body anchor?
- Is there any accidental permanent sidebar or decorative rail?
- Do the section label, title, reserved title field, body, and footer preserve
  their fixed vertical regions?
- Is there any decorative rule under an ordinary title? There should not be.
- Is school identity absent from the ordinary footer and concentrated on
  branded page families?
- Is every blue element on an ordinary page either page skeleton or an
  approved primary box title band?
- Outside box title bands, are headings, formulas, code, tables, and diagrams
  neutral?
- Is pink used as a box family rather than mistaken for semantic alert red?
- Is red exceptional and semantically tied to failure or alert state?
- Do list items preserve parallel wording and no more than two visible levels?
- Does every box clearly map to primary blue, secondary pink, or pink-alert
  semantics?
- Does the slide have one dominant composition?
- Do panels use the joined title-band/body-field grammar without borders or
  shadows?
- Are Chinese and English serving different hierarchy levels?
- Does every numbered page show physical document pagination?
- Does the frame compile without overfull or underfull boxes?