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Calendar

A month of days to pick from. It's the grid from the APG's date picker, with all the keyboard support you'd expect.

Element
<slab-calendar>
Built on
<table role=grid>
As Markdown
calendar.md

Example

Here's a styled version, <slab-styled-calendar>. It's not in the package — it's an example of what you can build with the headless element. Copy it and make it yours at the bottom of this page. Switch to "As it ships" to see the same markup with the headless element and no CSS at all. That's your starting point.

Styled example As it ships
HTML
<slab-styled-calendar min="2026-10-12" max="2026-12-18" value="2026-10-16"></slab-styled-calendar>
HTML
<slab-calendar min="2026-10-12" max="2026-12-18" value="2026-10-16"></slab-calendar>

Usage

Install
pnpm add slab-elements lit
HTML
<script type="module">
  import 'slab-elements/calendar.js';
</script>

<slab-calendar value="2026-03-14"></slab-calendar>

Keyboard

Key What it does
Left, Right Moves a day, into the month before or after at an end.
Up, Down Moves a week.
Home, End Moves to the start or end of the week.
Page Up, Page Down Moves back or forward a month. With Shift, a year.
Enter, Space Selects the day and dispatches “change”.

Behavior

A calendar with no visual styles: a month of days in a [role=grid], to pick one from, as in the APG's date picker.

Dates are ISO "yyyy-mm-dd" strings, as on a Date Field, and are worked out in UTC, so a change to or from daylight saving time never skips or repeats a day.

One day is tabbable: the selected one, or else today, kept between min and max. The arrow keys move a day or a week, into the month before or after when they reach an end. Home and End go to the start and end of the week, Page Up and Page Down go back and forward a month, and with Shift a year. Enter, Space and a click select the day and dispatch "change". Days before min or after max can't be reached or selected.

The month's name, the weekdays' and each day's full date are the browser's own, from Intl.DateTimeFormat, in the language of the nearest lang attribute. Slab ships no text, so the only words that aren't the browser's are the previous and next buttons', which previous-label and next-label set.

Style it through its parts. A day is also ::part(selected), ::part(today) and ::part(disabled) when it's those.

API

<slab-calendar>

Attributes
Name Type Default Description
max string The latest date that can be selected, as "yyyy-mm-dd".
min string The earliest date that can be selected, as "yyyy-mm-dd".
next-label string The next month button's text and so its accessible name. "Next month" when unset.
previous-label string The previous month button's text and so its accessible name. "Previous month" when unset.
value string '' The selected date, as "yyyy-mm-dd", or an empty string. Like a native input, the attribute is the default value and the property is the current one.
week-start number 0 The day weeks start on, from 0 for Sunday to 6 for Saturday.
version string
Methods
Signature Description
focus(options?: FocusOptions): void
Events
Name Type Description
change Event
CSS parts
Name Description
day A day of the month
disabled A day before the earliest date or after the latest
empty A cell before the first day of the month or after the last
grid The days
header The month and the buttons that change it
heading The month and year
next The button to the next month
previous The button to the previous month
selected The selected day
today Today
weekday A day of the week, above the days

Copy and own it

<slab-styled-calendar> isn't in the package. It's an example — copy it into your project and change whatever you want. Under the hood, it's just the headless element, subclassed, with styles set. That's it. Keyboard, focus, ARIA, forms, and events all come from the headless element, and the styles only reach in through ::part() and :state(), same as yours would.

To use it, copy these files, swap the tag in @customElement() for one of your own, and import it. tokens.styles.ts holds the colors and fonts every styled example shares, so you only need it once.

calendar.ts 
import { customElement } from 'lit/decorators.js';
import Calendar from 'slab-elements/calendar.js';
import styles from './calendar.styles.js';
import tokens from './tokens.styles.js';

declare global {
  interface HTMLElementTagNameMap {
    'slab-styled-calendar': StyledCalendar;
  }
}

/**
 * Calendar, styled: a raised slab of days, with today ringed in ember and
 * the selected day in ink.
 */
@customElement('slab-styled-calendar')
export default class StyledCalendar extends Calendar {
  static override styles = [tokens, styles];
}
calendar.styles.ts 
import { css } from 'lit';

/*
  The previous and next buttons' text is their accessible name, so it stays,
  at no size, and a chevron is drawn in its place.
*/
export default css`
  :host {
    background-color: var(--paper);
    border: var(--border);
    box-shadow: var(--shadow);
    color: var(--ink);
    display: inline-block;
    font-family: var(--font-body);
    padding: 1rem;
  }

  [part~='header'] {
    align-items: center;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
    margin-block-end: 0.75rem;
  }

  [part~='heading'] {
    font-family: var(--font-display);
    font-size: 1.125rem;
    font-weight: 600;
  }

  [part~='previous'],
  [part~='next'] {
    align-items: center;
    background-color: var(--paper);
    block-size: 2.25rem;
    border: var(--border);
    color: var(--ink);
    cursor: pointer;
    display: flex;
    font-size: 0;
    inline-size: 2.25rem;
    justify-content: center;
    padding: 0;
    transition: background-color 100ms;

    &::before {
      block-size: 0.5rem;
      border-block-end: 2px solid currentcolor;
      border-inline-start: 2px solid currentcolor;
      content: '';
      inline-size: 0.5rem;
      rotate: 45deg;
      translate: 0.125rem 0;
    }

    &:hover {
      background-color: var(--chalk);
    }

    &:focus-visible {
      outline: 3px solid var(--ember);
      outline-offset: 2px;
    }
  }

  [part~='next']::before {
    rotate: -135deg;
    translate: -0.125rem 0;
  }

  /*
    Separate rather than collapsed, so each day draws its own border whole.
    Collapsed, a day's border merges with its neighbors' and today's ring
    breaks up.
  */
  [part~='grid'] {
    border-collapse: separate;
    border-spacing: 0;
  }

  [part~='weekday'] {
    color: var(--ash);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 400;
    padding-block-end: 0.375rem;
    text-transform: uppercase;
  }

  [part~='day'] {
    block-size: 2.5rem;
    border: 2px solid transparent;
    box-sizing: border-box;
    cursor: pointer;
    inline-size: 2.5rem;
    text-align: center;
    transition:
      background-color 100ms,
      color 100ms;

    &:hover {
      background-color: var(--chalk);
    }

    &:focus-visible {
      outline: 3px solid var(--ember);
      outline-offset: -3px;
    }
  }

  [part~='today'] {
    border-color: var(--ember);
  }

  /*
    The ring is inside the day, so on the selected one it's on ink, where
    ember falls short of 3:1 in the dark. The text's color always has the
    contrast.
  */
  [part~='selected'] {
    background-color: var(--ink);
    color: var(--paper);
    font-weight: 600;

    &:hover {
      background-color: var(--ink);
    }

    &:focus-visible {
      outline-color: currentcolor;
    }
  }

  [part~='disabled'] {
    color: var(--ash);
    cursor: not-allowed;
    text-decoration: line-through;

    &:hover {
      background-color: transparent;
    }
  }

  @media (prefers-reduced-motion: reduce) {
    [part~='previous'],
    [part~='next'],
    [part~='day'] {
      transition: none;
    }
  }
`;
tokens.styles.ts 
import { css } from 'lit';

/*
  The styled components' palette and type, taken from the logo: ink for the
  courses, ember for the base, paper behind them.

  Each is a short alias for a "--slab-styled-*" property, with the default as
  its fallback. Retheming is "--slab-styled-ember" and the rest on ":root",
  which every shadow root inherits. Were the defaults declared under those
  names here instead, each host's own declaration would shadow the page's.

  Each default is "light-dark()", so the components follow the page's
  "color-scheme": "dark" for dark, "light" for light, and "light dark" to
  follow the operating system. Ink and paper trade places in the dark, so
  ink is always the text and paper always what's behind it. Contrast is given
  as light, then dark.
*/
export default css`
  :host {
    /* Secondary text. 6.8:1 and 6.9:1 on paper. */
    --ash: var(--slab-styled-ash, light-dark(#5e5a55, #a8a19a));
    --border: 2px solid var(--ink);

    /* Behind disabled and read-only controls, and hovered rows. */
    --chalk: var(--slab-styled-chalk, light-dark(#f4f1ec, #2b2926));

    /*
      The logo's orange, brighter in the dark. 4.25:1 and 5.2:1 on paper is
      enough for borders, fills and large text, but not always for small text,
      which takes "--ember-deep".
    */
    --ember: var(--slab-styled-ember, light-dark(#d9492a, #ec5f3b));

    /*
      Orange for small text on paper, and for paper text on it. 5.7:1 and
      7.4:1.
    */
    --ember-deep: var(--slab-styled-ember-deep, light-dark(#b3381a, #ff8566));
    --font-body: var(
      --slab-styled-font-body,
      'IBM Plex Sans',
      system-ui,
      sans-serif
    );
    --font-display: var(
      --slab-styled-font-display,
      'Zilla Slab',
      rockwell,
      'Roboto Slab',
      serif
    );
    --font-mono: var(
      --slab-styled-font-mono,
      'IBM Plex Mono',
      ui-monospace,
      monospace
    );
    --ink: var(--slab-styled-ink, light-dark(#1c1c1c, #f4f1ec));
    --paper: var(--slab-styled-paper, light-dark(#fff, #1a1918));

    /* The hard, offset shadow a raised surface casts. */
    --shadow: 4px 4px 0 var(--ink);
  }
`;