CSS Layout Techniques

Box Model and Display Properties

Understanding the box model is fundamental to CSS layout.

The Box Model

.box {
  width: 300px;
  height: 200px;
  padding: 20px;
  border: 1px solid black;
  margin: 30px;
}
                                

/* Makes width include content, padding, and border */
* {
  box-sizing: border-box;
}
                                

Display Properties

Positioning Techniques

The position property determines how an element is positioned in the document flow.

.element { position: static; }

.element { 
  position: relative;
  top: 10px;
  left: 20px;
}

.parent {
  position: relative;
}
.child {
  position: absolute;
  top: 0;
  right: 0;
}

.header {
  position: fixed;
  top: 0;
  width: 100%;
}

.nav {
  position: sticky;
  top: 0;
  z-index: 100;
}

Z-Index and Stacking Context

The z-index property controls the vertical stacking order of elements.

.background {
  position: relative;
  z-index: 1;
}

.foreground {
  position: absolute;
  z-index: 2; /* Will appear above .background */
}

.tooltip {
  position: absolute;
  z-index: 100; /* Will appear above most elements */
}
                        

Flexbox Layout

Flexbox is a one-dimensional layout method designed for laying out items in rows or columns.

Flex Container Properties

.container {
  display: flex;
  
  /* Main axis direction */
  flex-direction: row | row-reverse | column | column-reverse;
  
  /* Wrapping behavior */
  flex-wrap: nowrap | wrap | wrap-reverse;
  
  /* Shorthand for direction and wrap */
  flex-flow: row wrap;
  
  /* Main axis alignment */
  justify-content: flex-start | flex-end | center | space-between | space-around | space-evenly;
  
  /* Cross axis alignment */
  align-items: stretch | flex-start | flex-end | center | baseline;
  
  /* Multi-line alignment */
  align-content: flex-start | flex-end | center | space-between | space-around | stretch;
}
                        

Flex Item Properties

.item {
  /* Order (default: 0) */
  order: 1;
  
  /* Grow factor (default: 0) */
  flex-grow: 1;
  
  /* Shrink factor (default: 1) */
  flex-shrink: 0;
  
  /* Base size (default: auto) */
  flex-basis: 200px;
  
  /* Shorthand for grow, shrink, basis */
  flex: 1 0 auto;
  
  /* Individual alignment override */
  align-self: auto | flex-start | flex-end | center | baseline | stretch;
}
                        

Common Flexbox Patterns

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-links {
  display: flex;
  gap: 20px;
}
                                

.card-container {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}

.card {
  flex: 1 0 300px;
  max-width: calc(33.333% - 20px);
}
                                

Grid Layout

CSS Grid is a two-dimensional layout system designed for complex layouts.

Grid Container Properties

.container {
  display: grid;
  
  /* Define columns */
  grid-template-columns: 200px 1fr 2fr;
  
  /* Define rows */
  grid-template-rows: auto 300px auto;
  
  /* Column gaps */
  column-gap: 20px;
  
  /* Row gaps */
  row-gap: 20px;
  
  /* Shorthand for both gaps */
  gap: 20px;
  
  /* Named areas */
  grid-template-areas: 
    "header header header"
    "sidebar content content"
    "footer footer footer";
    
  /* Alignment of all items along row axis */
  justify-items: start | end | center | stretch;
  
  /* Alignment of all items along column axis */
  align-items: start | end | center | stretch;
  
  /* Alignment of the entire grid within container (row axis) */
  justify-content: start | end | center | stretch | space-around | space-between | space-evenly;
  
  /* Alignment of the entire grid within container (column axis) */
  align-content: start | end | center | stretch | space-around | space-between | space-evenly;
}
                        

Grid Item Properties

.item {
  /* Column start/end lines */
  grid-column-start: 1;
  grid-column-end: 3;
  
  /* Row start/end lines */
  grid-row-start: 1;
  grid-row-end: 3;
  
  /* Shorthand for column start/end */
  grid-column: 1 / 3;
  
  /* Shorthand for row start/end */
  grid-row: 1 / 3;
  
  /* Shorthand for both row and column */
  grid-area: 1 / 1 / 3 / 3;
  
  /* Named area placement */
  grid-area: header;
  
  /* Individual alignment override (row axis) */
  justify-self: start | end | center | stretch;
  
  /* Individual alignment override (column axis) */
  align-self: start | end | center | stretch;
}
                        

Advanced Grid Techniques

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 20px;
}
                                

.layout {
  display: grid;
  grid-template-columns: 200px 1fr;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "header header"
    "sidebar content"
    "footer footer";
  height: 100vh;
}

.header { grid-area: header; }
.sidebar { grid-area: sidebar; }
.content { grid-area: content; }
.footer { grid-area: footer; }
                                

Multi-column Layout

CSS Multi-column Layout allows content to flow into multiple columns, similar to newspaper layouts.

.content {
  /* Number of columns */
  column-count: 3;
  
  /* Width of columns */
  column-width: 200px;
  
  /* Gap between columns */
  column-gap: 40px;
  
  /* Line between columns */
  column-rule: 1px solid #ccc;
  
  /* Prevent element breaking across columns */
  .no-break {
    break-inside: avoid;
  }
  
  /* Force element to span all columns */
  .full-width {
    column-span: all;
  }
}
                        

Modern Layout Features

Subgrid

Subgrid allows grid items that are also grid containers to inherit the grid tracks from their parent.

.parent-grid {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: auto auto;
}

.child-grid {
  grid-column: 2 / 7;
  display: grid;
  grid-template-columns: subgrid;
}
                        

Container Queries

Container queries allow you to apply styles based on the size of a containing element rather than the viewport.

.card-container {
  container-type: inline-size;
  container-name: card;
}

@container card (min-width: 400px) {
  .card {
    display: flex;
  }
  
  .card-image {
    width: 40%;
  }
  
  .card-content {
    width: 60%;
  }
}
                        

Aspect Ratio

The aspect-ratio property allows you to maintain proportional dimensions for elements.

.video-container {
  width: 100%;
  aspect-ratio: 16 / 9;
}

.profile-image {
  width: 200px;
  aspect-ratio: 1 / 1;
  object-fit: cover;
}
                        

Logical Properties

Logical properties allow you to write direction-independent styles that work with different writing modes and text directions.

/* Instead of this (physical properties) */
.box {
  margin-left: 20px;
  padding-right: 15px;
  border-top: 1px solid black;
}

/* Use this (logical properties) */
.box {
  margin-inline-start: 20px;
  padding-inline-end: 15px;
  border-block-start: 1px solid black;
}
                        

Responsive Layout Strategies

Mobile-First Approach

/* Base styles for mobile */
.container {
  display: flex;
  flex-direction: column;
}

/* Tablet styles */
@media (min-width: 768px) {
  .container {
    flex-direction: row;
    flex-wrap: wrap;
  }
  
  .item {
    flex: 0 0 50%;
  }
}

/* Desktop styles */
@media (min-width: 1024px) {
  .item {
    flex: 0 0 33.333%;
  }
}
                        

Fluid Layouts

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.fluid-image {
  width: 100%;
  height: auto;
}

.fluid-typography {
  font-size: clamp(1rem, 2.5vw, 1.5rem);
}
                        

CSS Grid for Responsive Layouts

.layout {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-areas:
    "header header header header"
    "main main main sidebar"
    "footer footer footer footer";
  gap: 20px;
}

@media (max-width: 768px) {
  .layout {
    grid-template-columns: 1fr;
    grid-template-areas:
      "header"
      "main"
      "sidebar"
      "footer";
  }
}

.header { grid-area: header; }
.main { grid-area: main; }
.sidebar { grid-area: sidebar; }
.footer { grid-area: footer; }