[Python] Using Tailwindcss with weasyprint in python

I am trying to use tailwindcss with weasyprint in python to generate PDFs but it doesn't apply any of the classes. Not sure what I'm doing wrong.

Very basic template:

templates/basic.html

<!DOCTYPE html>
<html>

<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>

<body>
<h1 class="text-3xl font-bold underline">Hello world!</h1>
<div class="foo">This is a Foo</div>
</body>
</html>


with this CSS:

assets/basic.css

@import "tailwindcss";

.foo {
font-size: 12px;
}


I know I need to compile the CSS and use the compiled version with weasyprint, to i do this in my Dockerfile

FROM node:20-alpine AS node-builder

WORKDIR /tmp
RUN npm install tailwindcss @tailwindcss/cli

FROM node-builder AS tailwind-base

COPY --from=node-builder /tmp/node_modules /tmp/node_modules
COPY --from=backend-base /app/assets/*.css /tmp/
COPY --from=backend-base /app/templates/ /tmp/templates/

WORKDIR /tmp
RUN npx @tailwindcss/cli -i ./basic.css -o ./basic.compiled.css


I then copy the compiled css into my app stage

COPY --from=tailwind-base /tmp/basic.compiled.css /app/css/basic.compiled.css

and use it with weasyprint:

css = CSS("/app/css/basic.compiled.css")
html = HTML(string=self.to_html(), base_url="/app/")
virtual_file = BytesIO()
html.write_pdf(target=virtual_file, stylesheets=[css])


the resulting compiled CSS:

/*! tailwindcss v4.1.12 | MIT License | https://tailwindcss.com */
@layer properties;
@layer theme, base, components, utilities;
@layer theme {
:root, :host {
--font-sans: ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji",
"Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
--font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
"Courier New", monospace;
--text-xs: 0.75rem;
--text-xs--line-height: calc(1 / 0.75);
--text-xl: 1.25rem;
--text-xl--line-height: calc(1.75 / 1.25);
--text-3xl: 1.875rem;
--text-3xl--line-height: calc(2.25 / 1.875);
--font-weight-bold: 700;
--default-font-family: var(--font-sans);
--default-mono-font-family: var(--font-mono);
}
}
@layer base {
*, ::after, ::before, ::backdrop, ::file-selector-button {
box-sizing: border-box;
margin: 0;
padding: 0;
border: 0 solid;
}
html, :host {
line-height: 1.5;
-webkit-text-size-adjust: 100%;
tab-size: 4;
font-family: var(--default-font-family, ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji");
font-feature-settings: var(--default-font-feature-settings, normal);
font-variation-settings: var(--default-font-variation-settings, normal);
-webkit-tap-highlight-color: transparent;
}
hr {
height: 0;
color: inherit;
border-top-width: 1px;
}
abbr:where([title]) {
-webkit-text-decoration: underline dotted;
text-decoration: underline dotted;
}
h1, h2, h3, h4, h5, h6 {
font-size: inherit;
font-weight: inherit;
}
a {
color: inherit;
-webkit-text-decoration: inherit;
text-decoration: inherit;
}
b, strong {
font-weight: bolder;
}
code, kbd, samp, pre {
font-family: var(--default-mono-font-family, ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace);
font-feature-settings: var(--default-mono-font-feature-settings, normal);
font-variation-settings: var(--default-mono-font-variation-settings, normal);
font-size: 1em;
}
small {
font-size: 80%;
}
sub, sup {
font-size: 75%;
line-height: 0;
position: relative;
vertical-align: baseline;
}
sub {
bottom: -0.25em;
}
sup {
top: -0.5em;
}
table {
text-indent: 0;
border-color: inherit;
border-collapse: collapse;
}
:-moz-focusring {
outline: auto;
}
progress {
vertical-align: baseline;
}
summary {
display: list-item;
}
ol, ul, menu {
list-style: none;
}
img, svg, video, canvas, audio, iframe, embed, object {
display: block;
vertical-align: middle;
}
img, video {
max-width: 100%;
height: auto;
}
button, input, select, optgroup, textarea, ::file-selector-button {
font: inherit;
font-feature-settings: inherit;
font-variation-settings: inherit;
letter-spacing: inherit;
color: inherit;
border-radius: 0;
background-color: transparent;
opacity: 1;
}
:where(select:is([multiple], [size])) optgroup {
font-weight: bolder;
}
:where(select:is([multiple], [size])) optgroup option {
padding-inline-start: 20px;
}
::file-selector-button {
margin-inline-end: 4px;
}
:laceholder {
opacity: 1;
}
@supports (not (-webkit-appearance: -apple-pay-button)) or (contain-intrinsic-size: 1px) {
:laceholder {
color: currentcolor;
@supports (color: color-mix(in lab, red, red)) {
color: color-mix(in oklab, currentcolor 50%, transparent);
}
}
}
textarea {
resize: vertical;
}
::-webkit-search-decoration {
-webkit-appearance: none;
}
::-webkit-date-and-time-value {
min-height: 1lh;
text-align: inherit;
}
::-webkit-datetime-edit {
display: inline-flex;
}
::-webkit-datetime-edit-fields-wrapper {
padding: 0;
}
::-webkit-datetime-edit, ::-webkit-datetime-edit-year-field, ::-webkit-datetime-edit-month-field, ::-webkit-datetime-edit-day-field, ::-webkit-datetime-edit-hour-field, ::-webkit-datetime-edit-minute-field, ::-webkit-datetime-edit-second-field, ::-webkit-datetime-edit-millisecond-field, ::-webkit-datetime-edit-meridiem-field {
padding-block: 0;
}
::-webkit-calendar-picker-indicator {
line-height: 1;
}
:-moz-ui-invalid {
box-shadow: none;
}
button, input:where([type="button"], [type="reset"], [type="submit"]), ::file-selector-button {
appearance: button;
}
::-webkit-inner-spin-button, ::-webkit-outer-spin-button {
height: auto;
}
[hidden]:wherenot([hidden="until-found"])) {
display: none !important;
}
}
@layer utilities {
.text-3xl {
font-size: var(--text-3xl);
line-height: var(--tw-leading, var(--text-3xl--line-height));
}
.text-xl {
font-size: var(--text-xl);
line-height: var(--tw-leading, var(--text-xl--line-height));
}
.text-xs {
font-size: var(--text-xs);
line-height: var(--tw-leading, var(--text-xs--line-height));
}
.font-bold {
--tw-font-weight: var(--font-weight-bold);
font-weight: var(--font-weight-bold);
}
.underline {
text-decoration-line: underline;
}
}
.foo {
font-size: 6px;
}
@property --tw-font-weight {
syntax: "*";
inherits: false;
}
@layer properties {
@supports ((-webkit-hyphens: none) and (not (margin-trim: inline))) or ((-moz-orient: inline) and (not (color:rgb(from red r g b)))) {
*, ::before, ::after, ::backdrop {
--tw-font-weight: initial;
}
}
}


The .foo works but not the H1. I copied that from the get started guide on tailwindcss docs.

tailwindcss version v4.1.12 weasyprint version v66.0

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