/* display: block (default for div, p, h1-h6) */
.block-element {
  display: block;
  width: 100%;
  height: 100px;
  margin: 10px;
  padding: 10px;
}

/* Takes full width, stacks vertically */

/* display: inline (default for span, a, strong) */
.inline-element {
  display: inline;
  width: auto;
  height: auto;
  margin: 10px 0;
  padding: 5px 10px;
}

/* Flows with text, ignores height/width */

/* display: inline-block (hybrid) */
.inline-block-element {
  display: inline-block;
  width: 200px;
  height: 100px;
  margin: 10px;
  padding: 10px;
}

/* Flows inline but respects box model */

/* display: flex (layout mode) */
.flex-container {
  display: flex;
  gap: 20px;
  align-items: center;
}

/* Children become flex items */

/* display: grid (layout mode) */
.grid-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

/* Children become grid items */

/* display: none (hidden) */
.hidden {
  display: none;
}

/* Make a span behave like a block */
span {
  display: block;
  width: 100%;
  margin: 10px 0;
}

/* Now span stacks vertically and has width */

/* Make a div flow inline with text */
div {
  display: inline;
  margin: 0;
}

/* Now div flows horizontally like text */

/* Make a button behave like an inline element (unusual) */
button {
  display: inline;
}

/* Common: make list items display inline for navigation */
ul {
  list-style: none;
  padding: 0;
}

li {
  display: inline-block;
  margin: 0 10px;
}

/* Navigation: ul becomes flex container */
nav ul {
  display: flex;
  gap: 20px;
  list-style: none;
  padding: 0;
}

nav li {
  display: block;
}

/* Gallery: items become inline-block for wrapping */
.gallery {
  font-size: 0;
}

.gallery-item {
  display: inline-block;
  width: 200px;
  margin: 10px;
  font-size: 16px;
}

/* display: none vs visibility: hidden */

/* display: none: element removed from layout entirely */
.hidden-none {
  display: none;
}

/* visibility: hidden: element invisible but takes space */
.hidden-visibility {
  visibility: hidden;
}

/* display: contents (newer, powerful) */
.container {
  display: contents;
}

/* display: flow-root (new) */
.bfc {
  display: flow-root;
}

/* display: list-item (keeps list behavior) */
li {
  display: list-item;
}

/* display: table variants (less common) */
table {
  display: table;
}

tr {
  display: table-row;
}

td {
  display: table-cell;
}

/* display: flex opens up new properties */
.flex-container {
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  gap: 20px;
}

/* display: grid opens up grid properties */
.grid-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-gap: 20px;
}

/* display: block with positioning */
.positioned {
  display: block;
  position: absolute;
  top: 0;
  left: 0;
}

/* display: none ignores everything else */
.hidden {
  display: none;
  width: 100px;
  height: 100px;
  flex: 1;
  position: absolute;
}

/* display: inline-block with position */
.popup {
  display: inline-block;
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

/* 1. Use semantic HTML first */

/* Default display is semantic */

/* 2. Modern layouts: flex or grid, not inline-block */
/* Old way: inline-block for navigation */
li {
  display: inline-block;
  margin: 0 10px;
}

/* Modern way: flex */
ul {
  display: flex;
  gap: 10px;
  list-style: none;
  padding: 0;
}

/* 3. Use display: none for hidden content, not visibility: hidden */
.hidden {
  display: none;
}

/* 4. Don't fight natural display behavior */
/* Good: work with defaults */
button {
  padding: 10px 20px;
}

/* 5. Use display: contents sparingly */
.wrapper {
  display: contents;
}

/* 6. Don't mix conflicting display values */
/* Bad: flex + inline-block fighting */
.flex-container {
  display: flex;
}

.child {
  display: inline-block;
}

/* Good: let flex parent handle layout */
.flex-container {
  display: flex;
  gap: 20px;
}

.child {
  flex: 1;
}