/*! normalize.css v8.0.0 | MIT License | github.com/necolas/normalize.css */

/* Document
   ========================================================================== */

/**
 * 1. 修正所有浏览器中的行高.
 * 2. 在iOS的切换横竖屏时，防止字体大小的调整.
 */

 html {
    line-height: 1.15; /* 1 */
    -webkit-text-size-adjust: 100%; /* 2 */
  }
  
  /* Sections
     ========================================================================== */
  
  /**
   * 删除所有浏览器的margin值。
   */
  
  body {
    margin: 0;
  }
  
  /**
   * Correct the font size and margin on `h1` elements within `section` and
   * `article` contexts in Chrome, Firefox, and Safari.
   * 修正h1元素的font-size和margin值
   */
  
  h1 {
    font-size: 2em;
    margin: 0.67em 0;
  }
  
  /* Grouping content
     ========================================================================== */
  
  /**
   * 1. Add the correct box sizing in Firefox.
   * 2. Show the overflow in Edge and IE.
   * 1.修正火狐浏览器的box-sizing
   */
  
  hr {
    box-sizing: content-box; /* 1 */
    height: 0; /* 1 */
    overflow: visible; /* 2 */
  }
  
  /**
   * 1. Correct the inheritance and scaling of font size in all browsers.
   * 1. 在所有浏览器中纠正字体大小的继承和扩展。
   * 2. Correct the odd `em` font sizing in all browsers.
   * 2. 在所有浏览器中纠正奇数的字体大小。
   */
  
  pre {
    font-family: monospace, monospace; /* 1 */
    font-size: 1em; /* 2 */
  }
  
  /* Text-level semantics：文本级别的语义
     ========================================================================== */
  
  /**
   * Remove the gray background on active links in IE 10.
   * 删除IE 10中活跃链接的灰色背景。
   */
  
  a {
    background-color: transparent;
  }
  
  /**
   * 1. Remove the bottom border in Chrome 57-
   * 1. 移除Chrome 57-浏览器的border-bottom
   * 2. Add the correct text decoration in Chrome, Edge, IE, Opera, and Safari.
   * 2. 在Chrome、Edge、IE、Opera和Safari中添加正确的text-decoration。
   */
  
  abbr[title] {
    border-bottom: none; /* 1 */
    text-decoration: underline; /* 2 */
    text-decoration: underline dotted; /* 2 */
  }
  
  /**
   * Add the correct font weight in Chrome, Edge, and Safari.
   * 在Chrome、Edge和Safari中添加正确的font-weight
   */
  
  b,
  strong {
    font-weight: bolder;
  }
  
  /**
   * 1. Correct the inheritance and scaling of font size in all browsers.
   * 1.在所有浏览器中纠正字体大小的继承和扩展。
   * 2. Correct the odd `em` font sizing in all browsers.
   */
  
  code,
  kbd,
  samp {
    font-family: monospace, monospace; /* 1 */
    font-size: 1em; /* 2 */
  }
  
  /**
   * Add the correct font size in all browsers.
   */
  
  small {
    font-size: 80%;
  }
  
  /**
   * Prevent `sub` and `sup` elements from affecting the line height in
   * all browsers.
   * 防止“sub”和“sup”元素影响所有浏览器的线高度。
   */
  
  sub,
  sup {
    font-size: 75%;
    line-height: 0;
    position: relative;
    vertical-align: baseline;
  }
  
  sub {
    bottom: -0.25em;
  }
  
  sup {
    top: -0.5em;
  }
  
  /* Embedded content：嵌入命令
     ========================================================================== */
  
  /**
   * Remove the border on images inside links in IE 10.
   */
  
  img {
    border-style: none;
  }
  
  /* Forms
     ========================================================================== */
  
  /**
   * 1. Change the font styles in all browsers.
   * 2. Remove the margin in Firefox and Safari.
   */
  
  button,
  input,
  optgroup,
  select,
  textarea {
    font-family: inherit; /* 1 */
    font-size: 100%; /* 1 */
    line-height: 1.15; /* 1 */
    margin: 0; /* 2 */
  }
  
  /**
   * Show the overflow in IE.
   * 1. Show the overflow in Edge.
   */
  
  button,
  input { /* 1 */
    overflow: visible;
  }
  
  /**
   * Remove the inheritance of text transform in Edge, Firefox, and IE.
   * 在Edge、Firefox和IE中删除文本转换的继承。
   * 1. Remove the inheritance of text transform in Firefox.
   * 1. 删除Firefox中文本转换的继承。
   */
  
  button,
  select { /* 1 */
    text-transform: none;
  }
  
  /**
   * Correct the inability to style clickable types in iOS and Safari.
   * 纠正在iOS和Safari中无法使用可点击类型的功能。
   */
  
  button,
  [type="button"],
  [type="reset"],
  [type="submit"] {
    -webkit-appearance: button;
  }
  
  /**
   * Remove the inner border and padding in Firefox.
   * 移除Firefox中border和padding
   */
  
  button::-moz-focus-inner,
  [type="button"]::-moz-focus-inner,
  [type="reset"]::-moz-focus-inner,
  [type="submit"]::-moz-focus-inner {
    border-style: none;
    padding: 0;
  }
  
  /**
   * Restore the focus styles unset by the previous rule.
   * 恢复以前规则未设置的焦点样式。
   */
  
  button:-moz-focusring,
  [type="button"]:-moz-focusring,
  [type="reset"]:-moz-focusring,
  [type="submit"]:-moz-focusring {
    outline: 1px dotted ButtonText;
  }
  
  /**
   * Correct the padding in Firefox.
   * 修正火狐的padding值
   */
  
  fieldset {
    padding: 0.35em 0.75em 0.625em;
  }
  
  /**
   * 1. Correct the text wrapping in Edge and IE.
   * 1. 
   * 2. Correct the color inheritance from `fieldset` elements in IE.
   * 2. 从IE的“fieldset”元素中纠正颜色继承。
   * 3. Remove the padding so developers are not caught out when they zero out
   *    `fieldset` elements in all browsers.
   * 3.
   */
  
  legend {
    box-sizing: border-box; /* 1 */
    color: inherit; /* 2 */
    display: table; /* 1 */
    max-width: 100%; /* 1 */
    padding: 0; /* 3 */
    white-space: normal; /* 1 */
  }
  
  /**
   * Add the correct vertical alignment in Chrome, Firefox, and Opera.
   * 在Chrome、Firefox和Opera中添加正确的垂直对齐方式。
   */
  
  progress {
    vertical-align: baseline;
  }
  
  /**
   * Remove the default vertical scrollbar in IE 10+.
   * 删除IE 10+中的默认垂直滚动条
   */
  
  textarea {
    overflow: auto;
  }
  
  /**
   * 1. Add the correct box sizing in IE 10.
   * 1. 修正IE10中的box-sizing
   * 2. Remove the padding in IE 10.
   * 2. 移除IE10的padding值
   */
  
  [type="checkbox"],
  [type="radio"] {
    box-sizing: border-box; /* 1 */
    padding: 0; /* 2 */
  }
  
  /**
   * Correct the cursor style of increment and decrement buttons in Chrome.
   * 修正Chrome中增加和减量按钮的光标样式。
   */
  
  [type="number"]::-webkit-inner-spin-button,
  [type="number"]::-webkit-outer-spin-button {
    height: auto;
  }
  
  /**
   * 1. Correct the odd appearance in Chrome and Safari.
   * 1. 修正在Chrome和Safari中出现的奇怪现象。
   * 2. Correct the outline style in Safari.
   * 2. 修正Safari中的outline样式
   */
  
  [type="search"] {
    -webkit-appearance: textfield; /* 1 */
    outline-offset: -2px; /* 2 */
  }
  
  /**
   * Remove the inner padding in Chrome and Safari on macOS.
   * 移除chrome和macos上的Safari的padding值
   */
  
  [type="search"]::-webkit-search-decoration {
    -webkit-appearance: none;
  }
  
  /**
   * 1. Correct the inability to style clickable types in iOS and Safari.
   * 1. 纠正在iOS和Safari中无法使用可点击类型的功能。
   * 2. Change font properties to `inherit` in Safari.
   * 2. 在Safari中更改字体属性，以“inherit”。
   */
  
  ::-webkit-file-upload-button {
    -webkit-appearance: button; /* 1 */
    font: inherit; /* 2 */
  }
  
  /* Interactive：交互式的
     ========================================================================== */
  
  /*
   * Add the correct display in Edge, IE 10+, and Firefox.
   * 修正Edge, IE 10+,和 Firefox中details标签的display属性
   */
  
  details {
    display: block;
  }
  
  /*
   * Add the correct display in all browsers.
   * 修正所有浏览器的display属性
   */
  
  summary {
    display: list-item;
  }
  
  /* Misc
     ========================================================================== */
  
  /**
   * Add the correct display in IE 10+.
   * 修正IE10+的template元素的display
   */
  
  template {
    display: none;
  }
  
  /**
   * Add the correct display in IE 10.
   * 修正IE 10中的display
   */
  
  [hidden] {
    display: none;
  }