Utilities for layout
For faster mobile-friendly and responsive development, Bootstrap includes dozens of utility classes for showing, hiding, aligning, and spacing content.
Use our display utilities for responsively toggling common values of the displayproperty. Mix it with our grid system, content, or components to show or hide them across specific viewports.
Bootstrap 4 is built with flexbox, but not every element's displayhas been changed to display: flexas this would add many unnecessary overrides and unexpectedly change key browser behaviors. Most of our components are built with flexbox enabled.
Should you need to add display: flexto an element, do so with .d-flexor one of the responsive variants (eg, .d-sm-flex). You'll need this class or displayvalue to allow the use of our extra flexbox utilities for sizing, alignment, spacing, and more.
Use the marginand padding spacing utilities to control how elements and components are spaced and sized. Bootstrap 4 includes a five-level scale for spacing utilities, based on a 1remvalue default $spacervariable. Choose values for all viewports (eg, .mr-3for margin-right: 1rem), or pick responsive variants to target specific viewports (eg, .mr-md-3for margin-right: 1remstarting at the mdbreakpoint).
When toggling displayisn't needed, you can toggle the visibilityof an element with our visibility utilities . Invisible elements will still affect the layout of the page, but are visually hidden from visitors.