Display, Position & Overflow

display controls how an element behaves in layout. block elements take full width and start on a new line. inline elements flow with text. none hides the element completely.

CSS Display

display controls how an element behaves in layout. block elements take full width and start on a new line. inline elements flow with text. none hides the element completely.

Real-life example: block is like a full-width bus stop. inline is like a word in a sentence. none is like removing a poster from the wall.

display values

.block-box {
  display: block;
  background: #ecfeff;
  margin-bottom: 1rem;
}

.hidden-mobile {
  display: none; /* use carefully — still in DOM */
}

CSS Position

position sets how an element is placed. static is default. relative moves from its normal spot. absolute is placed inside a positioned parent. fixed sticks to the viewport. sticky blends both.

Real-life example: fixed is like a sticker on your phone screen that stays while you scroll. absolute is like placing a sticker inside one photo frame.

position types

.relative-badge {
  position: relative;
  top: 4px;
}

.parent {
  position: relative;
}

.badge {
  position: absolute;
  top: 8px;
  right: 8px;
  background: #ef4444;
  color: white;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  font-size: 0.75rem;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: white;
}

Position Offsets & z-index

top, right, bottom, and left move positioned elements. z-index controls stacking order — higher numbers appear on top.

Real-life example: z-index is like stack order of plates — the plate with the higher number sits on top.

Offsets and stacking

.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.5);
  z-index: 1000;
}

.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 1001;
  background: white;
  padding: 1.5rem;
  border-radius: 12px;
}

Overflow

overflow controls what happens when content is bigger than its box. hidden cuts off extra content. auto adds scrollbars when needed. scroll always shows scrollbars.

Real-life example: overflow: hidden is like a window too small for a long banner — you only see the part that fits.

overflow examples

.scroll-box {
  max-height: 200px;
  overflow-y: auto;
  border: 1px solid #e2e8f0;
  padding: 1rem;
}

.avatar-crop {
  width: 80px;
  height: 80px;
  overflow: hidden;
  border-radius: 50%;
}

Float (legacy) & inline-block

float was used for text wrapping around images and old layouts. Today prefer Flexbox and Grid. inline-block lets elements sit side by side but still accept width and height.

Real-life example: float is like an old boat layout — still floating in some old websites. inline-block is like small boxes that can sit in a row but still have fixed size.

float note and inline-block

/* Legacy — know it when reading old code */
.img-float {
  float: left;
  margin-right: 1rem;
}

/* Modern alternative for small rows */
.tag {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  background: #ecfeff;
  border-radius: 999px;
  margin: 0.25rem;
}

Align & Centering

text-align centers inline content. margin: auto centers block elements with a set width. For modern layouts, Flexbox and Grid centering are easier and more powerful.

Real-life example: margin: auto is like equal empty space on left and right of a car in a parking slot.

For new projects, use Flexbox or Grid for layout — not float.

Centering patterns

.narrow {
  max-width: 600px;
  margin-inline: auto;
  text-align: center;
}

.flex-center {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 200px;
}