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Styling — how it works here

Rule under the law docs/constitution/frontend-application.md. The law says what must be true; here — what it is called in this tree and where it lives. The layout of a component file — component-structure, state — angular-patterns, the browser environment — platform-access, the layer of calls to the server — api-layer. All five under one law.

Cold part: pitfalls.md next to it — traps already stepped on. Loaded on demand, not together with the rule.

What it is called here

In the law	Here
the shared set of styling values	the kit scales --rt-*; one's own on top of them — --<prefix>-* in the application's styles.scss
a class in the markup	the rtBlock and rtElem directives from @rt-tools, not a string in an attribute
a style rule	an &__<element> declaration in .scss — its own or in the application's shared layer
the shared layout layer	apps/<app>/src/styles/: <prefix>-page, <prefix>-form, <prefix>-panel, <prefix>-window in the admin, <prefix>-site-page on the site

Where it lives

In this tree — the table in implementation.md next to it. Paths live there, not here: the rule travels between repositories, the layout does not, and a path named in the rule lies in the first tree that keeps its code differently.

Flow

The flow of a styling edit: where a value comes from, where the layout lives and what opens an overlay.

flowchart TD
    A[Styling is edited] --> B{What is being set}
    B -->|Colour, spacing, font size| C[Taken as a styling token, not written as a value in place]
    B -->|Screen layout| D[Declared in the application's shared layer, not in the screen's styles]
    B -->|A layer above the page| E[Opened by the kit service; the layer number is taken from the scale]
    C --> F[The class is set by a directive, and every element class has its own rule]
    D --> F
    E --> F
    F --> G{The size of a control}
    G -->|Chosen by the pointer sign, not by the screen width| H[The styles file stays within the length limit]
    H --> I[The stylelint run: a warning fails it the same as an error]

How the law applies here

• Styling is taken as a --rt-* token, not written as a value in place. Composite values — box-shadow, text-shadow — are taken as a ready-made token whole, not assembled from parts.

  <!-- rt-when: *.scss *.css -->

• Every element class has its own style rule. A class without a rule looks working and silently does nothing.

  <!-- rt-when: *.scss *.css -->

• A class is set by a directive, not by a string in an attribute. rtElem gets the block name by injection from the nearest ancestor with rtBlock, and there is nothing to repeat that resolution by the text of the template.

  <!-- rt-when: *.html *.scss -->

• The layout is declared in the application's shared layer, not in the screen's styles. A screen component outside the kit has an empty styles file by default.

  <!-- rt-when: *.scss *.css -->

• One thing is called by one name in every place it occurs. A layout that keeps three vocabularies for the page, the edit panel and the window, with shared names in different meanings, does not count as a shared layer: the place of declaration matches, the meaning of the name does not. Choosing a name, the executor lands in a foreign vocabulary and brings a foreign spacing, and the checks do not see it. Where an element stands is set by the kind of block, not by a second set of names.

  <!-- rt-when: *.scss *.css *.html -->

• The sheet and the window are opened by the kit service, not by a layer number. The scale's numbers compare only between neighbours in the markup; the service moves the markup outside, to <body>, and there is nothing left to compare it with.

  <!-- rt-when: *.ts *.scss -->

• The layer number is taken from the scale, not written as a number in the component file. The scale is the only place where the layers are visible side by side: a number written in place does not land in it, and the next node takes the same number without learning of it.

  <!-- rt-when: *.scss *.css -->

• A width limit is declared together with the fate of what did not fit. A limit and a place in a row hide or wrap nothing by themselves: a node that may receive a value longer than its place has either ellipsis truncation or wrapping. Without that the text silently runs past the border and lies over its neighbour, and allowing an element to shrink does not replace truncation.

  <!-- rt-when: *.scss *.css -->

• Truncation goes in a pair with a tooltip. A truncated text without a tooltip reads as the whole value: a person has no way to learn where the text actually ends. The whole value they see either in the place itself or on hover — and a tooltip given a width limit of its own obeys the article above the same as a cell.

  <!-- rt-when: *.scss *.css -->

• The size of a control is chosen by the pointer sign, not by the screen width. A tablet in landscape is wider than the narrow-viewport threshold, yet it is tapped with a finger: pointer: coarse answers about the way of pressing, the width — about the room for the layout. The steps are taken from the kit, not assigned in pixels.

  <!-- rt-when: *.scss *.css -->

• A styles file is no longer than 500 lines. The limit is shared with code and texts, but stylelint does not judge length at all — a check of the tree holds it. A grown screen file is split by blocks, and shared layout leaves for its own layer.

  <!-- rt-when: *.scss *.css -->

• A stylelint warning fails the run the same as an error. !important is declared a warning, and the run goes with --max-warnings 0: otherwise the ban reads as a wish — two such warnings lay in the tree while npm run stylelint returned zero and was no gate.

  <!-- rt-when: *.scss *.css -->

What of the law is not here

The "class without a rule" check counts a match by element name, not by the pair "block — element": a class that has a rule, but under a foreign block, it lets through. The reverse direction — removing the rule of a live class — is not checked at all and is caught by reading the template.

Patterns

• styling-bem-layout — a screen on the shared layout layer, the application's blocks.
• styling-bem-component — styles of a kit component, :host, modifiers, the site's styling language.
• styling-bem-sheet — the sheet and the window above the page: what opens them, the backdrop, the measurement.