Component gallery

Typography

A .lead paragraph opens a section with a little more presence.

Body copy is set in IBM Plex Sans at a comfortable measure, with headings in Fraunces. Inline elements: inline_code(), ⌘ K, highlighted text, ADR, and a link. Sidenotes keep asides out of the main line of thought.On wide screens this floats into the margin; on narrow screens tap the number to expand it.

A third-level heading

Second-level headings get an automatic §n eyebrow and appear in the contents; third-level headings are indented beneath them.

Callouts

Badges

Draft Proposed Accepted In review Rejected Superseded High Medium Low v2.4.0

Cards & metrics

• 1

  Single source

  Tokens in one file drive every colour, size and duration.

• 2

  Both themes

  Light and dark from light-dark() — no duplicated rules.

• 3

  Degrades well

  No JavaScript? Steps become a list, tabs become sections.

Charts

Write the numbers as a table inside <bh-chart> to get a themed line or column chart. Hover, or focus the chart and use the arrow keys, to read every series at a point. The table stays one click away under “Show data”.

Comparisons & decisions

When the choice depends on how much each criterion matters, show the scoring with <bh-matrix>. Readers can move the weights and watch whether the leader changes.

Steps & timelines

1. Drain the node. Stop routing new traffic and wait for in-flight requests.
2. Upgrade. Apply the new image and restart the service.
3. Verify & restore. Health checks pass, then re-add to the pool.

1. 14:02
   Deploy begins

   Config change rolled to 5% of hosts.

2. 14:06
   Error rate spikes

   5xx climbs to 12% on canary hosts.

3. 14:09
   Alert fires

   On-call paged by SLO burn alert.

4. 14:15
   Rolled back

   Error rate returns to baseline.

Key-values & tables

Service

billing-api

Owner

Payments platform

Runtime

Rust 1.90, Tokio, Axum

Disclosure & predict-then-reveal

Code

Language classes get syntax highlighting (Prism, loaded only when needed). Every block gets a copy button; data-title labels it.

pub fn try_acquire(&mut self, now: Instant) -> bool {
    self.refill(now);                // ①
    if self.tokens >= 1.0 {
        self.tokens -= 1.0;          // ②
        true
    } else {
        false                        // ③
    }
}

Annotated code

let tokens = min(capacity, tokens + elapsed * rate);1
if tokens >= cost { tokens -= cost; allow() }2
else { reject(retry_after(cost - tokens)) }3

1. Refill lazily from elapsed time — no background timer needed.
2. Spend tokens only when the request is admitted.
3. Tell the client exactly when to come back.

Diffs

  timeout_ms: 2000
- retries: 5+ retries: 2+ retry_budget: 0.1  backoff: exponential

Code walkthrough

For explaining an implementation, <bh-codewalk> pins the code beside the prose. As you scroll, each step highlights its lines and shades the rest.

use std::time::{Duration, Instant};

pub struct TokenBucket {
    capacity: f64, // b: the largest burst
    rate: f64,     // r: tokens per second
    tokens: f64,
    last: Instant, // monotonic clock
}

impl TokenBucket {
    pub fn try_acquire(&mut self, cost: f64) -> Result<(), Duration> {
        let now = Instant::now();
        let elapsed = now.duration_since(self.last).as_secs_f64();
        self.tokens = (self.tokens + elapsed * self.rate).min(self.capacity);
        self.last = now;

        if self.tokens >= cost {
            self.tokens -= cost;
            Ok(())
        } else {
            Err(Duration::from_secs_f64((cost - self.tokens) / self.rate))
        }
    }
}

Diagrams

Inline SVG drawn with theme classes — .node.c1…c6, .edge, .zone, .label. Colours follow the theme; arrowheads are automatic. Pair a diagram with <bh-stepper for="…"> to walk through it. Each step is linkable (#gallery-arch-step-3), and the link button in the stepper bar copies a link to the current step.

• External
• Network edge
• Our service
• Storage
• Infrastructure

Prose can point into a diagram. Hover over the gateway, or over the service and its two stores, to light those parts. Click one to bring the diagram into view. Mark up the phrase with data-ref="figure-id:part-id …".

Current vs proposed

Wrap two versions of a diagram in <bh-versions> to switch between them, or press Compare and drag the divider. Mark parts with data-change="added|changed|removed" to show what the proposal changes.

Sequence diagrams

Describe actors and messages, and <bh-sequence> lays them out with the theme's vocabulary. Replies are dashed, notes sit over one or more lifelines, and every part keeps its data-id, so a stepper can walk through the exchange.

Mermaid (fallback)

For quick sequence or state diagrams, a <pre class="mermaid"> renders with theme colours (loaded from a CDN only when present). Prefer hand-placed SVG for anything central to the argument.

sequenceDiagram
    participant C as Client
    participant L as Limiter
    participant S as Service
    C->>L: request
    alt token available
      L->>S: forward
      S-->>C: 200 OK
    else bucket empty
      L-->>C: 429 Retry-After
    end

Tabs

let resp = client.get(url).send().await?;

resp, err := http.Get(url)

resp = httpx.get(url)

Playground

Named inputs feed data-expr outputs and data-bind attributes — live models with no custom script.

Glossary terms

Words defined in the glossary are underlined automatically the first time they appear on a page. Hover over one to see its definition. For example, a gateway might enforce a rate limit with a token bucket and answer rejected calls with Retry-After, keeping p99 latency inside the SLO.

The popup stays put while it's open. Move the pointer into it to select and copy text or follow its links. Click a term, or press Enter on it, to pin the popup; Esc or a click elsewhere closes it. To mark a word explicitly, use data-term="id", as in this GCRA reference. Add class="no-glossary" to keep a passage unmarked.

Layout

Children of .bh-article sit in the reading column. Add .wide to use the gutters, or .full to go edge to edge.