PraCha, home

The design system

Everything this site is made of, drawn by the same code that draws the site. If it is not here, it is not part of the system yet.

The visual library

Principles

  1. One anatomy on every page: header, page head, body with a margin, page foot, footer.
  2. Content is the only variable. Places differ in what they hold, never in where things go.
  3. Everything is an entry with an address: place, kind, date and slug give one permanent URL and one row.
  4. Visuals carry meaning: every mark is real or explains something real.
  5. Paper and three pigments: ink, indigo, maroon. One pigment per element; two never mix.
  6. Fraunces for titles, Figtree to read, JetBrains Mono for labels; Tamil is first-class.
  7. Nothing overlaps. No counts, no streaks. No em dashes. Works without JavaScript, on a phone, at night.

Colour · day

paper#fefdfathe ground
ink#141416text, ink lines
ink-2#3a3a40secondary text, graphite
muted#6b6b72meta, labels
rule#e6e4dfhairlines
field#f4f3efcode, quiet panels
maroon#7a1f2ethe one point: seal, result, state
indigo#2a3a7cwhat matters: links, the wash

Colour · night

paper#0f1019
ink#f1efe9
ink-2#c9c7c2
muted#9a99a3
rule#2a2c38
field#171925
maroon#e07f8c
indigo#9aa8f0

Type

nameFraunces 3.1remPrabakaran Chandran
h1 · titleFraunces 2.6remWhy does a network forget?
h2 · sectionFraunces 1.6remWhat happened
ledeFigtree 1.28remOne sentence saying what this is.
bodyFigtree 1.125rem / 1.62I chose control engineering somewhat by accident, and have looked at the world as a system ever since.
metaJetBrains Mono .78rem17 Oct 2026 · log · working
quoteFraunces 1.06remGet the essence, and express it in your own style.
TamilCatamaran · Noto Serif Tamilபிரபாகரன் சந்திரன்   கற்க கசடறக் கற்பவை

Space

4px
8px
12px
16px
24px
32px
48px
64px
96px

Grid

main · 42rem · text, pictures and figures, all on one margin

The order of making

Marks happen in the order a hand makes them, and each medium keeps to its job, its pigment and its place. Every engine, scene, collection and diagram is on the visual library.

Places

Components

G1 Header wordmark, places, the seal; the same on every page

At the top of this page.

G2 Footer contact, the record, elsewhere, the name line

At the foot of this page.

G3 Icons small marks on the things you click; one stroke in the text colour, or a service's own glyph

sharelinkmailinboxatrssdoclistuserleftrightoutdownloadcopychecksendbookarticlesearchgithubhuggingfacesubstackxwhatsapplinkedin

P1 Breadcrumb where this sits

P2 Page head title and one sentence

Causal State-Space Models for Time Series

Forecasting models predict what will happen — but decisions change the pattern. This integrates causal structure into sequence models so they can reason about interventions, not just correlations.

P3 Meta line date · kind · stage · modes

buildsettledscience · engineering

L1 Row the one list pattern

E7 Ensō on an inquiry's own page: the gap is how settled it is

E1 Frame the kind's summary in one place

E2 Figure numbered, captioned, in the house palette

Fig. 1The house plot style: ink data, one maroon point for the result, labels never on a line.

E5 Quote their own sentences, with the source

Get the essence and express it in my own style.

from The Artist and the Engineer, 2026

E6 Outcome a labelled result line in the Lab

failed The invariance penalty hurt every head.

E8 Code highlighted at build time, three pigments, a copy button

python
def forget_less(features, classes):
    # one covariance, pooled over every class seen so far
    mu = {k: features[classes == k].mean(0) for k in set(classes)}
    return mu, shrink(cov(features))

E9 Artwork an open-access work, shown whole and credited

A manuscript page showing a seated automaton figure holding a cup and a flower, its hidden pipes and floats drawn inside its body, beside Arabic text.
Figure for Use at Drinking Parties, folio from a Book of the Knowledge of Ingenious Mechanical Devices, Badi' al-Zaman ibn al-Razzaz al-Jazari, dated 715 AH/1315 CE. The Metropolitan Museum of Art, 55.121.12. CC0 1.0.

F1 Reply the end of every piece

If this was yours too, I'd like to hear it. Write to mepc3197@columbia.edu · the title goes in the subject line

F6 Share a small Share by the date; copy the link, or send it on, at the foot

F4 Letter line one input, one button, one promise

Sent through Substack, which will ask you to confirm. Your email is used for these letters and nothing else. Subscribe on Substack instead.

C6 Settled stamp the seal at the end of a settled piece

Settled · 27 Mar 2026

Where things live