Touch devices can trigger sticky or accidental hover states, especially when hover changes the DOM. @media (hover) and @media not all and (hover) help keep hover-only styling off devices that cannot hover.

Media queries can express basic logic for viewport ranges and device capabilities using and, commas, and not all and syntax.

Naming a controller action cookies can override ActionController cookie access and break unrelated requests, causing redirects or storage failures.

Migrate hashed settings stored in a single column by renaming keys safely in an ActiveRecord::Migration, using the store's coder and an embedded model.

Rails logs can be silenced completely in a specific environment by replacing the logger with Logger.new('/dev/null').

Production releases can be linked to Git history by tagging the deployed revision automatically with Capistrano.

Legacy authentication setups often miss SSL, cookie, CSRF, and session-fixation protections, leaving logins and browser-stored data easy to compromise.

currentColor reuses the current text color for borders and other CSS color values, avoiding duplicated color declarations and keeping states in sync.

MariaDB administrative access can be granted to a local user without a password, with unix_socket authentication, or by setting a password.

Browser fullscreen handling is inconsistent across vendors, forcing boilerplate and event workarounds. screenfull provides a small wrapper for cross-browser fullscreen requests, exit, state, and change events.

Monitor logs across multiple app servers from one terminal and avoid missing per-host errors; LOG selects another file, and terminal line truncation can hide long entries.

Capistrano can hide long command output with ellipses, making deployment logs harder to read. Disabling Airbrussh truncation keeps full server paths and responses visible.

Large JavaScript libraries can be loaded only when needed to keep initial bundles small and avoid duplicate script execution, memory leaks, and repeated event handlers.

Remove selected HTML tags while preserving their inner text and other child nodes using contents() and unwrap() in jQuery.

Rails console debugging for mail delivery failures, with ActionMailer settings inspection and a direct test message to verify SMTP and spam score.

Large PostgreSQL databases can hide tables that consume most disk space. pg_total_relation_size and pg_size_pretty help identify the biggest relations quickly.

Keep Rails or IRB commands available after exit by saving console history to a file and increasing the retained history length.

IRB may warn during boot when an alias conflicts with an existing method in its context, especially in programmatic setups.

Bundler can fail when a gem exposes dependencies missing from the API or lockfile; manually adding them to Gemfile.lock may restore bundle install.

Public file links in email can lose host and port information; combining root_url with a CarrierWave file path keeps contract URLs usable in mailers.

RubyGems 2.5.1 can raise Gem::Package::PathError during installation when the target path is invalid; updating RubyGems with gem update --system often resolves it.

Flexbox and Grid both handle responsive layout, but Flexbox fits one-dimensional arrangements while Grid is built for two-dimensional page structures.