fix(ui): Fix bugs in the UI

[julialeex]

Before

1. Things on the chat page are not aligned (see image)
2. The search bar text font is too big (see gif)
3. The search bar moves while typing (see gif)

After

1. Everything is aligned
2. Smaller font
3. Make the search bar not move while typing

Test plan

CI & local tests

[abeatrix]

lgtm!

[sourcegraph-release-bot]

The backport to M68 failed at https://github.com/sourcegraph/cody/actions/runs/13209043570:

The process '/usr/bin/git' failed with exit code 1

To backport this PR manually, you can either:

Via the sg tool

Use the sg backport command to backport your commit to the release branch.

sg backport -r M68 -p 7001

Via your terminal

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-M68 M68
# Navigate to the new working tree
cd .worktrees/backport-M68
# Create a new branch
git switch --create backport-7001-to-M68
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 d17c277efe2415d07f533801d29d9fb3274f1b5f
# Push it to GitHub
git push --set-upstream origin backport-7001-to-M68
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-M68

If you encouter conflict, first resolve the conflict and stage all files, then run the commands below:

git cherry-pick --continue
# Push it to GitHub
git push --set-upstream origin backport-7001-to-M68
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-M68

• Follow above instructions to backport the commit.
• Create a pull request where the base branch is M68 and the compare/head branch is backport-7001-to-M68., click here to create the pull request.

Once the pull request has been created, please ensure the following:

• Make sure to tag @sourcegraph/release in the pull request description.

• kindly remove the release-blocker from this pull request.

[sourcegraph-release-bot]

The backport to M68 failed at https://github.com/sourcegraph/cody/actions/runs/13209377869:

The process '/usr/bin/git' failed with exit code 1

To backport this PR manually, you can either:

Via the sg tool

Use the sg backport command to backport your commit to the release branch.

sg backport -r M68 -p 7001

Via your terminal

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-M68 M68
# Navigate to the new working tree
cd .worktrees/backport-M68
# Create a new branch
git switch --create backport-7001-to-M68
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 d17c277efe2415d07f533801d29d9fb3274f1b5f
# Push it to GitHub
git push --set-upstream origin backport-7001-to-M68
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-M68

If you encouter conflict, first resolve the conflict and stage all files, then run the commands below:

git cherry-pick --continue
# Push it to GitHub
git push --set-upstream origin backport-7001-to-M68
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-M68

• Follow above instructions to backport the commit.
• Create a pull request where the base branch is M68 and the compare/head branch is backport-7001-to-M68., click here to create the pull request.

Once the pull request has been created, please ensure the following:

• Make sure to tag @sourcegraph/release in the pull request description.

• kindly remove the release-blocker from this pull request.