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Alignment

Height Alignment Pattern​

  • border simulation.
  • Negative margin.
  • absolute element: .absolute { top: 0; bottom: 0; } 使所有子元素 (absolute) 与父元素 (relative) 等高.
  • table layout: display: table-cell 默认等高.
  • flex layout: flex items 默认拉伸至盒子高度.
  • grid layout: grid items 默认等高.

Border Simulation Height Alignment​

/* 导航背景区 border 创建 */
.box {
  background-color: #f0f3f9;
  border-left: 150px solid #333;
}

/* 清除浮动影响 */
.box::after {
  clear: both;
  display: block;
  content: '';
}

/* 布局主结构 */
.box > nav {
  float: left;
  width: 150px;
  margin-left: -150px;
}

.box > section {
  overflow: hidden;
}

Negative Margin Height Alignment​

.column-box {
  overflow: hidden; /* hidden overflow background */
}

/* 视觉等高布局 */
.column-left,
.column-right {
  padding-bottom: 9999px;
  margin-bottom: -9999px;
}

Layout Height Alignment​

.table {
  display: table;
  overflow: hidden;

  .left {
    display: table-cell;
    width: 200px;
    background: #4caf50;
  }

  .right {
    display: table-cell;
    width: 800px;
    background: #99afe0;
  }
}

.flex {
  display: flex;
  flex-flow: row nowrap;
  align-items: stretch;

  .left {
    flex: 200px 0 0;
    background: #4caf50;
  }

  .right {
    flex: auto 1 0;
    background: #99afe0;
  }
}

.grid {
  display: grid;
  grid-template-columns: 200px auto;
  align-items: stretch;

  .left {
    background: #4caf50;
  }

  .right {
    background: #99afe0;
  }
}

Centering Pattern​

Centering Pattern

Horizontal Centering Pattern​

Horizontal Centering Inline Element​

  • text-align: center.
  • flex.
  • grid.
.quote {
  text-align: center;
}

Horizontal Centering Block Element​

  • Auto margin.
  • flex.
  • grid.
.row {
  width: 100%;
  max-width: var(--row-max-width);
  margin: 0 auto;
}

.container {
  max-width: 1024px;
  margin: 0 auto;
}

父元素 float, 父子元素 relative:

.container {
  position: relative;
  left: 50%;
  float: left;
}

.container ul {
  position: relative;
  left: -50%;
}

Vertical Centering Pattern​

Vertical Centering Inline element​

  • line-height.
  • vertical-align: middle:
    • 作用机制: 对齐基线 (baseline) 往上 1/2 x-height 高度 (即小写字母 x 交叉点处).
    • 作用环境: parent element line-height === height.
    • 作用对象: children inline/inline-block/table-cell element.
  • Vertical parent padding.
  • flex.
  • grid.

Button label (<a>) vertical alignment (行内块居中法:

a.button::before {
  display: inline-block;
  height: 16px;
  vertical-align: middle;
  content: '';
}

Vertical Centering Block element​

  • top + translateY.
  • vertical-align: middle + display: table-cell: 表格单元居中法.
  • Vertical margin.
  • Vertical padding.
  • flex.
  • grid.
.viewport-centered-block {
  width: 18em;
  margin: 50vh auto 0;
  transform: translateY(-50%);
}

.form-item-label {
  display: flex;
  flex-direction: row;
  align-items: center;
}

Mixing Centering Pattern​

.box {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  transform-style: preserve-3d; /* Remove blurry in WebKit browsers */
  backface-visibility: hidden; /* Remove blurry in WebKit browsers */
}

.dialog {
  position: absolute;
  inset: 0;
  width: fit-content;
  height: fit-content;
  margin: auto;
}

References​

  • Centering layout complete guide.
  • CSS layout guide.