# Less

線上編輯器: <http://winless.org/online-less-compiler>

## 安裝

NPM

```
npm install less -g
```

新建一個檔案名為test.less

```
@base: #f938ab;

.box-shadow(@style, @c) when (iscolor(@c)) {
  -webkit-box-shadow: @style @c;
  box-shadow:         @style @c;
}
.box-shadow(@style, @alpha: 50%) when (isnumber(@alpha)) {
  .box-shadow(@style, rgba(0, 0, 0, @alpha));
}
.box {
  color: saturate(@base, 5%);
  border-color: lighten(@base, 30%);
  div { .box-shadow(0 0 5px, 30%) }
}
```

進行編譯

```
lessc test.less test.css
```

CDN

```
<script src="//cdnjs.cloudflare.com/ajax/libs/less.js/2.5.3/less.min.js"></script>
```

開啟線上編繹器進行練習

## 1.定義變數與使用四則運算

```
@nice-blue: #5B83AD;
@light-blue: @nice-blue * 1.5;

#header {
  color: @light-blue;
}
```

## 2.使用Mixin

(將 css規則直接塞入其他css規則中)

```
.bordered {
  border-top: dotted 1px black;
  border-bottom: solid 2px black;
}

#menu a {
  color: #111;
  .bordered;
}

.post a {
  color: red;
  .bordered;
}
```

## 3.更加清楚的子代規則

(以下面為例，選取id header內所有 相關class)

```
#header {
  color: black;
}
#header .navigation {
  font-size: 12px;
}
#header .logo {
  width: 300px;
}
```

可寫成這樣

```
#header {
  color: black;
  .navigation {
    font-size: 12px;
  }
  .logo {
    width: 300px;
  }
}
```

虛擬元素記得前面+&

```
.clearfix {
  display: block;
  zoom: 1;

  &:after {
    content: " ";
    display: block;
    font-size: 0;
    height: 0;
    clear: both;
    visibility: hidden;
  }
}
```

## 4指定選擇器名稱的變數

```
@mySelector: banner;

.@{mySelector} {
  font-weight: bold;
  line-height: 40px;
  margin: 0 auto;
}
```

參考至:

中文:<http://less.bootcss.com/features/#features-overview-feature>

英文:<http://lesscss.org/>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://easonwang.gitbook.io/web_basic/css-advance/less.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.