CSS Grids

Grid Container

<div class="container">
  <div class="item item-1"> </div>
  <div class="item item-2"> </div>
  <div class="item item-3"> </div>
</div>

Grid Item

<div class="container">
  <div class="item"> </div>
  <div class="item">
    <p class="sub-item"> </p>
  </div>
  <div class="item"> </div>
</div>

.item {
  grid-column-start: <number> | <name> | span <number> | span <name> | auto;
  grid-column-end: <number> | <name> | span <number> | span <name> | auto;
  grid-row-start: <number> | <name> | span <number> | span <name> | auto;
  grid-row-end: <number> | <name> | span <number> | span <name> | auto;
}

.item-a {
  grid-column-start: 2;
  grid-column-end: five;
  grid-row-start: row1-start;
  grid-row-end: 3;
}

.item-b {
  grid-column-start: 1;
  grid-column-end: span col4-start;
  grid-row-start: 2;
  grid-row-end: span 2;
}

.container {
  grid-template-columns: ...  ...;
  /* e.g. 
      1fr 1fr
      minmax(10px, 1fr) 3fr
      repeat(5, 1fr)
      50px auto 100px 1fr
  */
  grid-template-rows: ... ...;
  /* e.g. 
      min-content 1fr min-content
      100px 1fr max-content
  */
}

.container {
  grid-template-columns: [first] 40px [line2] 50px [line3] auto [col4-start] 50px [five] 40px [end];
  grid-template-rows: [row1-start] 25% [row1-end] 100px [third-line] auto [last-line];
}

.container {
  grid-template-rows: [row1-start] 25% [row1-end row2-start] 25% [row2-end];
}

.container {
  grid-template-columns: repeat(3, 20px [col-start]);
}

.container {
  grid-template-columns: 20px [col-start] 20px [col-start] 20px [col-start];
}

.item {
  grid-column: <start-line> / <end-line> | <start-line> / span <value>;
  grid-row: <start-line> / <end-line> | <start-line> / span <value>;
}

.item-c {
  grid-column: 3 / span 2;
  grid-row: third-line / 4;
}

.item {
  grid-column-start: col-start 2;
}

.container {
  grid-template-columns: 1fr 1fr 1fr;
}

.container {
  grid-template-columns: 1fr 50px 1fr 1fr;
}

.item {
  grid-area: <name> | <row-start> / <column-start> / <row-end> / <column-end>;
}

.container {
  grid-template-areas: 
    "<grid-area-name> | . | none | ..."
    "...";
    }
    
    .item-a {
  grid-area: header;
}
.item-b {
  grid-area: main;
}
.item-c {
  grid-area: sidebar;
}
.item-d {
  grid-area: footer;
}

.container {
  display: grid;
  grid-template-columns: 50px 50px 50px 50px;
  grid-template-rows: auto;
  grid-template-areas: 
    "header header header header"
    "main main . sidebar"
    "footer footer footer footer";
}