2018-10-10 22:03:03 +00:00
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---
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id: 5a9d72ad424fe3d0e10cad16
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2020-12-16 07:37:30 +00:00
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title: 使用媒体查询更改变量
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2018-10-10 22:03:03 +00:00
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challengeType: 0
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2019-12-13 05:47:57 +00:00
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videoUrl: 'https://scrimba.com/c/cWmL8UP'
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forumTopicId: 301091
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2021-01-13 02:31:00 +00:00
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dashedName: use-a-media-query-to-change-a-variable
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2018-10-10 22:03:03 +00:00
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2021-01-08 19:20:48 +00:00
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CSS 变量可以简化媒体查询的定义方式。
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2018-10-10 22:03:03 +00:00
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2021-01-08 19:20:48 +00:00
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例如,当屏幕小于或大于媒体查询所设置的值,只要我们更新变量的值,那么使用了此变量的元素样式就都会更改。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --instructions--
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2018-10-10 22:03:03 +00:00
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2021-02-06 04:42:36 +00:00
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在 `media query`(媒体查询)声明的 `:root` 选择器里,重定义 `--penguin-size` 的值为 `200px`。 同时,重新定义 `--penguin-skin` 的值为 `black`, 然后通过缩放页面来查看它们是否生效。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2021-01-08 19:20:48 +00:00
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`:root` 中的 `--penguin-size` 值应为 `200px`。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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code.match(
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/media\s*?\(\s*?max-width\s*?:\s*?350px\s*?\)\s*?{[\s\S]*:root\s*?{[\s\S]*--penguin-size\s*?:\s*?200px\s*?;[\s\S]*}[\s\S]*}/gi
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)
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);
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2018-10-10 22:03:03 +00:00
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```
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2021-01-08 19:20:48 +00:00
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`:root` 中的 `--penguin-skin` 值应为 `black`。
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2019-12-13 05:47:57 +00:00
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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code.match(
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/media\s*?\(\s*?max-width\s*?:\s*?350px\s*?\)\s*?{[\s\S]*:root\s*?{[\s\S]*--penguin-skin\s*?:\s*?black\s*?;[\s\S]*}[\s\S]*}/gi
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)
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);
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2018-10-10 22:03:03 +00:00
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```
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2019-12-13 05:47:57 +00:00
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --seed-contents--
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```html
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<style>
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:root {
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--penguin-size: 300px;
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--penguin-skin: gray;
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--penguin-belly: white;
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--penguin-beak: orange;
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}
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@media (max-width: 350px) {
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:root {
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/* Only change code below this line */
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/* Only change code above this line */
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}
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}
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.penguin {
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position: relative;
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margin: auto;
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display: block;
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margin-top: 5%;
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width: var(--penguin-size, 300px);
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height: var(--penguin-size, 300px);
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}
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.right-cheek {
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top: 15%;
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left: 35%;
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background: var(--penguin-belly, white);
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width: 60%;
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height: 70%;
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border-radius: 70% 70% 60% 60%;
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}
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.left-cheek {
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top: 15%;
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left: 5%;
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background: var(--penguin-belly, white);
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width: 60%;
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height: 70%;
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border-radius: 70% 70% 60% 60%;
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}
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.belly {
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top: 60%;
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left: 2.5%;
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background: var(--penguin-belly, white);
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width: 95%;
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height: 100%;
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border-radius: 120% 120% 100% 100%;
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}
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.penguin-top {
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top: 10%;
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left: 25%;
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background: var(--penguin-skin, gray);
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width: 50%;
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height: 45%;
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border-radius: 70% 70% 60% 60%;
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}
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.penguin-bottom {
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top: 40%;
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left: 23.5%;
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background: var(--penguin-skin, gray);
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width: 53%;
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height: 45%;
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border-radius: 70% 70% 100% 100%;
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}
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.right-hand {
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top: 5%;
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left: 25%;
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background: var(--penguin-skin, black);
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width: 30%;
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height: 60%;
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border-radius: 30% 30% 120% 30%;
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transform: rotate(130deg);
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z-index: -1;
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animation-duration: 3s;
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animation-name: wave;
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animation-iteration-count: infinite;
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transform-origin:0% 0%;
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animation-timing-function: linear;
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}
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@keyframes wave {
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10% {
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transform: rotate(110deg);
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}
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20% {
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transform: rotate(130deg);
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}
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30% {
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transform: rotate(110deg);
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}
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40% {
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transform: rotate(130deg);
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}
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}
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.left-hand {
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top: 0%;
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left: 75%;
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background: var(--penguin-skin, gray);
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width: 30%;
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height: 60%;
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border-radius: 30% 30% 30% 120%;
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transform: rotate(-45deg);
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z-index: -1;
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}
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.right-feet {
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top: 85%;
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left: 60%;
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background: var(--penguin-beak, orange);
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width: 15%;
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height: 30%;
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border-radius: 50% 50% 50% 50%;
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transform: rotate(-80deg);
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z-index: -2222;
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}
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.left-feet {
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top: 85%;
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left: 25%;
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background: var(--penguin-beak, orange);
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width: 15%;
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height: 30%;
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border-radius: 50% 50% 50% 50%;
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transform: rotate(80deg);
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z-index: -2222;
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}
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.right-eye {
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top: 45%;
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left: 60%;
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background: black;
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width: 15%;
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height: 17%;
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border-radius: 50%;
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}
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.left-eye {
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top: 45%;
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left: 25%;
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background: black;
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width: 15%;
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height: 17%;
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border-radius: 50%;
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}
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.sparkle {
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top: 25%;
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left:-23%;
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background: white;
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width: 150%;
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height: 100%;
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border-radius: 50%;
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}
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.blush-right {
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top: 65%;
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left: 15%;
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background: pink;
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width: 15%;
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height: 10%;
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border-radius: 50%;
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}
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.blush-left {
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top: 65%;
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left: 70%;
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background: pink;
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width: 15%;
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height: 10%;
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border-radius: 50%;
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}
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.beak-top {
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top: 60%;
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left: 40%;
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background: var(--penguin-beak, orange);
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width: 20%;
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height: 10%;
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border-radius: 50%;
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}
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.beak-bottom {
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top: 65%;
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left: 42%;
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background: var(--penguin-beak, orange);
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width: 16%;
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height: 10%;
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border-radius: 50%;
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}
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body {
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background:#c6faf1;
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}
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.penguin * {
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position: absolute;
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}
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</style>
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<div class="penguin">
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<div class="penguin-bottom">
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<div class="right-hand"></div>
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<div class="left-hand"></div>
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<div class="right-feet"></div>
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<div class="left-feet"></div>
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</div>
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<div class="penguin-top">
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<div class="right-cheek"></div>
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<div class="left-cheek"></div>
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<div class="belly"></div>
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<div class="right-eye">
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<div class="sparkle"></div>
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</div>
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<div class="left-eye">
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<div class="sparkle"></div>
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</div>
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<div class="blush-right"></div>
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<div class="blush-left"></div>
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<div class="beak-top"></div>
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<div class="beak-bottom"></div>
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</div>
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</div>
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```
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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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```html
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<style>@media (max-width: 350px) {:root {--penguin-size: 200px; --penguin-skin: black;}}</style>
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```
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