📐Grid System
container / container-fluidResponsive container
container-{sm|md|lg|xl|xxl}Breakpoint containers
rowRow wrapper
col / col-{n}Column (n = 1-12)
col-md-66 cols from md up
col-sm-12 col-md-6 col-lg-4Responsive columns
offset-md-3Offset 3 columns
g-3 / gx-3 / gy-3Gutter utilities
row-cols-3Auto-distribute columns
order-first / order-last / order-{n}Column ordering
⚡Flexbox Utilities
d-flex / d-inline-flexEnable flex
justify-content-{start|center|end|between|around}JC
align-items-{start|center|end|stretch}AI
align-self-{value}Self align
flex-wrap / flex-nowrapWrap
flex-fill / flex-grow-1 / flex-shrink-0Flex grow/shrink
gap-3Gap
ms-auto / me-autoMargin auto (push)
↔️Spacing
m-3 / mx-3 / my-3Margin all/x/y
mt-3 / me-3 / mb-3 / ms-3Individual (t/end/b/start)
p-3 / px-3 / py-3Padding all/x/y
pt-3 / pe-3 / pb-3 / ps-3Individual padding
Scale: 0=0 1=0.25rem 2=0.5rem 3=1rem 4=1.5rem 5=3remScale
m-auto / mx-autoAuto margin (centering)
🔠Typography
h1 – h6 / .h1 – .h6Heading classes
display-1 to display-6Display headings
leadLarge intro text
small / .smallSmall text
text-mutedMuted/secondary text
text-{start|center|end}Text alignment
fw-bold / fw-semibold / fw-normal / fw-lightFont weight
fst-italic / fst-normalFont style
text-uppercase / text-lowercase / text-capitalizeTransform
text-truncateSingle-line truncation
lh-1 / lh-sm / lh-base / lh-lgLine height
🎨Colors & Backgrounds
text-primary/secondary/success/danger/warning/infoText colors
text-body / text-muted / text-whiteSemantic text
bg-primary/.../bg-body/bg-transparentBackgrounds
bg-opacity-50Background opacity
bg-gradientApply gradient
text-bg-primaryBg + contrasting text
link-primary/danger/...Colored links
🖱️Buttons
btnBase button class
btn-primary / btn-secondarySolid buttons
btn-outline-primaryOutlined button
btn-sm / btn-lgSize variants
btn-block (d-grid)Full-width button
disabledDisabled state
btn-closeX close button
btn-group / btn-group-verticalButton group
🧩Components
card / card-body / card-headerCard component
card-title / card-text / card-footerCard parts
navbar / navbar-brand / nav-linkNavigation
navbar-togglerMobile toggle
dropdown / dropdown-toggle / dropdown-menuDropdown
modal / modal-dialog / modal-contentModal
alert alert-primaryAlert boxes
badge bg-primaryBadge
spinner-border / spinner-growLoading spinners
toastToast notification
accordionCollapsible content
offcanvasSlide-out panel
📝Forms
form-controlInput / textarea / select styling
form-labelInput label
form-check / form-check-input / form-check-labelCheckbox/radio
form-selectStyled select
form-floatingFloating label
form-textHelp text
is-valid / is-invalidValidation states
valid-feedback / invalid-feedbackFeedback messages
input-group / input-group-textInput addons
🔧Utilities
d-none / d-block / d-{bp}-flexDisplay
d-none d-md-blockHide on mobile
position-relative/absolute/fixed/stickyPosition
top-0 / start-0 / end-0 / bottom-0Offsets
translate-middleCenter absolutely-positioned
rounded / rounded-pill / rounded-circleBorder radius
shadow / shadow-sm / shadow-lgShadows
overflow-hidden / overflow-autoOverflow
w-100 / w-75 / w-50Width utilities
vh-100 / h-100Height utilities
visually-hiddenAccessible hide