cssgridgenerator
App UI

CSS Grid Chat App Layout Generator

Conversation list, message thread and a composer pinned to the bottom.

Open in
1080px

Drag across the grid to draw an area. Arrow keys nudge, Shift + arrows resize.

space to pan · ⌘scroll to zoom
1300px2minmax(0, 1fr)3
1auto21fr3auto4
thread-head1 / 2 / 2 / 3
messages2 / 2 / 3 / 3
composer3 / 2 / 4 / 3
convos1 / 1 / 4 / 2

Reading orderAt Desktop, convos is the first thing seen but thread-head is the first thing focused. Placement has moved the layout out of document order, so keyboard and screen reader users get a different sequence from everyone else.

Seenconvos → thread-head → messages → composer

Focusedthread-head → messages → composer → convos

Usually the fix is in the markup, not in CSS: reorder the children so the HTML reads the way the page does, then place them back where you want them. Reaching for order or row-reverse instead moves the picture without moving the focus, which is the bug rather than the cure.

It is not always wrong. A full-height sidebar beside a topbar diverges by construction, and the accepted answer there is a skip link to the main content rather than a reordered document. WCAG 2.2 SC 1.3.2 asks that the sequence be meaningful — not that it be identical.

Named areas. The CSS is a picture of the layout, and only the properties that actually change get repeated inside each media query.

.chat {
  display: grid;
  grid-template-columns: 1fr;
  grid-template-rows: auto 1fr auto;
  gap: 0;
  grid-template-areas:
    "thread-head"
    "messages"
    "composer";
}

.chat > .thread-head { grid-area: thread-head; }
.chat > .messages { grid-area: messages; }
.chat > .composer { grid-area: composer; }
.chat > .convos { display: none; }

@media (min-width: 900px) {
  .chat {
    grid-template-columns: 300px minmax(0, 1fr);
    grid-template-areas:
      "convos thread-head"
      "convos messages"
      "convos composer";
  }

    .chat > .convos { grid-area: convos; }
}

How this layout works

The thread column is auto 1fr auto: a header that stays, a message list that takes the remaining height and scrolls, and a composer that grows as the draft gets longer. The composer being auto rather than a fixed height is what lets it expand to three lines without maths.

Pin the scroll to the bottom the cheap way: display: flex; flex-direction: column-reverse on the message list, or overflow-anchor plus a scroll-to-bottom on new messages. Grid places the list; keeping it stuck to the newest message is a separate job.

On mobile the conversation list and the thread are two screens, not two columns. The generator hides the list at the narrow breakpoint — route between them instead of trying to fit both.

Every property used here is listed in the CSS Grid cheat sheet, with the reason to reach for it.

Frequently asked questions

How do I pin a chat composer to the bottom?
Make the thread column auto 1fr auto: header, scrolling messages, composer. The composer row is auto, so it grows as the draft wraps to two or three lines without any height calculation.
Should the conversation list and thread share a screen on mobile?
No. They are two screens with navigation between them. Squeezing both into a phone width leaves neither usable, which is why every native mail and chat app routes rather than splits.
How do I center a grid in CSS?
Use justify-content: center on the grid container to centre the whole grid inside it, and margin-inline: auto with a max-width to centre the container in the page. These are different jobs: the first moves the tracks within the container, the second moves the container itself.
How do I center items inside a CSS grid?
Set place-items: center on the container. That is shorthand for align-items plus justify-items, and it centres every item inside its own cell on both axes. For a single item, use place-self: center on that item instead.
How do I make a CSS grid responsive?
Use grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)) and it reflows at every width with no media queries at all. Add breakpoints only when the exact column count matters, or when the layout has to change shape rather than just wrap.
When should I use CSS Grid instead of Flexbox?
Use Grid when things must line up in two directions at once, and Flexbox when content flows along one axis. A page skeleton or dashboard is Grid; a navbar or row of buttons is Flexbox. They nest: Grid for the page, Flexbox inside the cells.

How to use it

  1. Open the pattern

    The chat app layout loads into the editor already responsive, with every breakpoint set up.

  2. Change the tracks

    Edit the column and row sizes in the Tracks panel. Anything valid in a track list works.

  3. Redraw at another width

    Move the ruler past a breakpoint marker and rearrange. Only the placement changes.

  4. Copy the code

    Take CSS, HTML, Tailwind or a shadcn component. The media queries are already written.

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