# [CSS]CSS notes
###### tags: `css`

## grid
### tuts
https://www.daconote.com/css-gride-fr/

## transform
### 移除transform

  .btn:disabled:active{
      transform:none;
    }

## var
### basics
https://www.w3schools.com/css/css3_variables.asp

:root {
  --blue: #1e90ff;
  --white: #ffffff;
}

body { background-color: var(--blue); }

h2 { border-bottom: 2px solid var(--blue); }

## 圖片相關
### 圖片大小與比例調整: objec-fit
https://www.w3schools.com/css/css3_object-fit.asp

## rwd相關
### 根據寬度縮放文字
https://stackoverflow.com/questions/16056591/font-scaling-based-on-width-of-container


## 尺寸相關

### px與em的換算
http://www.flycan.com/article/css/css-em-to-px-87.html

網頁文字預設大小為16px
1em = 16px

線上換算
http://pxtoem.com/

## flexbox相關

對齊flexbox item內的文字
https://stackoverflow.com/questions/25311541/how-to-vertically-align-text-inside-a-flexbox

>將該item也設定為display:flex後
>再用align-items跟justify-content去對齊文字

 *{
        box-sizing: border-box;
        margin: 0px;
        padding: 0px;
        border: black solid 1px;
      }
      body{
        border: rebeccapurple 2px solid;
        height: 300px;

      }
      .flex-container{
        margin-top: 5%;
        margin-left: 5%;
        border: grey 1px solid;
        display: flex;
        flex-direction: row;
        height: 50%;
        width: 50%;
        align-items: center;
        /* justify-content: space-between; */

      }
      .flex-container .flex-item{
        border: black 1px solid;
        /* height: 20%; */
        width: 100%;
        display: flex;
        align-items: center;
        justify-content: center;
      }
      .item1{
        background-color: green;
        height: 50px;
      }
      .item2{
        background-color: goldenrod;
        height: 20%;
      }
      .item3{
        background-color: wheat;
        height: 80%;
      }

<div class="flex-container">
  <div class="flex-item item1">
    <div>item1 txt</div>
  </div>
  <div class="flex-item item2">item2</div>
  <div class="flex-item item3">item3</div>
</div>

## 選擇器

### 僅在按鈕為非disabled時才有hover效果
https://stackoverflow.com/questions/26754497/css-disable-hover-effect

css

.btnStart {

/*  若按鈕為disabled,hover效果不作用 */
  &:not(:disabled):hover{
  background-color: rgb(110, 187, 189);
  color: #000;
  }

## 對齊

### 垂直置中
#### 絕對位置垂直置中

top:50%;
transform: translateY(-50%);

### 水平&垂直置中

position:absolute;
transform:translate(-50%,-50%);

### 水平置中
方1

margin: 20px auto

方2

display:grid;
place-items: center;

### 使文字置中對齊
水平:text-center
垂直:line-height

html

<div class="block">Click Me</div>

css

.block{
  width: 400px;
  height: 400px;
  line-height: 400px;
  text-align: center;
}