CSS Position Property — How static, relative, absolute, fixed, and sticky Actually Work

/* This does absolutely nothing */
.element {
  position: static;
  top: 50px; /* Ignored! */
  z-index: 999; /* Ignored! */
}

.badge {
  position: relative;
  top: -10px;  /* Moves UP 10px from original position */
  left: 5px;   /* Moves RIGHT 5px from original position */
}

/* Common use: creating a positioning context for absolute children */
.card {
  position: relative; /* This is the key! */
}
.card .badge {
  position: absolute;
  top: -8px;
  right: -8px;
}

/* Notification badge on an icon */
.icon-wrapper {
  position: relative; /* Creates positioning context */
  display: inline-block;
}

.notification-dot {
  position: absolute;
  top: -4px;
  right: -4px;
  width: 8px;
  height: 8px;
  background: red;
  border-radius: 50%;
}

/* Modal overlay */
.modal-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  /* Or: inset: 0; (shorthand) */
  background: rgba(0, 0, 0, 0.5);
}

/* Sticky header */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: white;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

/* Don't forget to add padding to body! */
body {
  padding-top: 64px; /* Height of navbar */
}

/* Back to top button */
.back-to-top {
  position: fixed;
  bottom: 20px;
  right: 20px;
}

/* Cookie banner */
.cookie-banner {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
}

/* Sticky table headers */
.table thead th {
  position: sticky;
  top: 0;
  background: white;
  z-index: 10;
}

/* Sticky sidebar */
.sidebar {
  position: sticky;
  top: 80px; /* Below fixed navbar */
  height: fit-content;
}

/* Section headers that stick during scroll */
.section-header {
  position: sticky;
  top: 0;
  background: var(--background);
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
}

/* ❌ Sticky won't work if any ancestor has overflow: hidden */
.parent {
  overflow: hidden; /* This kills sticky! */
}
.child {
  position: sticky; /* Won't stick */
  top: 0;
}

/* ❌ Also won't work without a threshold */
.element {
  position: sticky; /* Missing top/bottom/left/right! */
}

/* ✅ Fix: Remove overflow:hidden from ancestors OR restructure HTML */

/* ❌ Fixed element inside a transformed parent doesn't work as expected */
.parent {
  transform: translateX(0); /* Creates new containing block! */
}
.child {
  position: fixed; /* Now fixed relative to .parent, not viewport! */
  top: 0;
}

/* This also applies to: filter, perspective, will-change, contain */