CSS Positioning

Absolute, relative, fixed, sticky, and stacking contexts.

Overview

Positioning controls element placement and layering.

Key Concepts

• Static — Default flow
• Relative — Offset from normal position
• Absolute — Relative to positioned ancestor
• Fixed — Relative to viewport
• Sticky — Hybrid of relative and fixed

Code Examples

/* Relative positioning */
.relative {
  position: relative;
  top: 10px;
  left: 20px;
}

/* Absolute positioning */
.container {
  position: relative;
}

.absolute-child {
  position: absolute;
  top: 0;
  right: 0;
}

/* Fixed header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: white;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.page-content {
  padding-top: 80px; /* Offset for fixed header */
}

/* Sticky elements */
.sticky-sidebar {
  position: sticky;
  top: 100px;
  align-self: flex-start;
}

/* Centering with position */
.center-absolute {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

/* Stacking contexts */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1000;
}

.overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 999;
  background: rgba(0, 0, 0, 0.5);
}

/* Tooltip positioning */
.tooltip {
  position: relative;
}

.tooltip-content {
  position: absolute;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%);
  z-index: 10;
}

/* Dropdown */
.dropdown {
  position: relative;
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  z-index: 50;
}

/* Sticky table header */
.table-wrapper {
  max-height: 400px;
  overflow-y: auto;
}

.table thead th {
  position: sticky;
  top: 0;
  background: white;
  z-index: 1;
}

Practice

Build a sticky header with a fixed sidebar layout.