HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.
In CodePen, whatever you write in the HTML editor is what goes within the <body>
tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html>
tag. If you want to add classes there that can affect the whole document, this is the place to do it.
In CodePen, whatever you write in the HTML editor is what goes within the <body>
tags in a basic HTML5 template. If you need things in the <head>
of the document, put that code here.
The resource you are linking to is using the 'http' protocol, which may not work when the browser is using https.
CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.
It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.
To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit-
or -moz-
.
We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).
Any URLs added here will be added as <link>
s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.
You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself.
You can also link to another Pen here (use the .css
URL Extension) and we'll pull the CSS from that Pen and include it. If it's using a matching preprocessor, use the appropriate URL Extension and we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.
JavaScript preprocessors can help make authoring JavaScript easier and more convenient.
Babel includes JSX processing.
Any URL's added here will be added as <script>
s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.
You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.
If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.
You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.
Search for and use JavaScript packages from npm here. By selecting a package, an import
statement will be added to the top of the JavaScript editor for this package.
Using packages here is powered by Skypack, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ES6 import
usage.
All packages are different, so refer to their docs for how they work.
If you're using React / ReactDOM, make sure to turn on Babel for the JSX processing.
If active, Pens will autosave every 30 seconds after being saved once.
If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.
If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.
Visit your global Editor Settings.
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css">
<body>
<div class="traka">
<span class="logo">
<img src="http://upload.wikimedia.org/wikipedia/commons/9/93/Solid_color_You_Tube_logo.png">
</span>
<input type="search" placeholder="Search">
<div id="menu">
<ul>
<li><i class="fa fa-envelope-o" id="poruke"></i></li>
<li><i class="fa fa-bell-o" id="notifikacije"></i></li>
<li><i class="fa fa-caret-down" id="down"></i></li>
</ul>
<img src="https://i.imgur.com/GjLlmP6.jpg">
</div>
<input type="button" value="Upload">
</div>
<div class="strana">
<ul>
<li id="title"><strong>Menu</strong></li>
<a href="#"><li><i class="fa fa-youtube-play"></i>What to watch</li></a>
<a href="#"><li><i class="fa fa-user"></i>My Channel</li></a>
<a href="#"><li><i class="fa fa-clock-o"></i>History</li></a>
<a href="#"><li><i class="fa fa-play-circle-o"></i>Watch later</li></a>
</ul>
<ul>
<li id="title"><strong>Playlists</strong><a href="#"><i class="fa fa-cog"></i></a></li>
<a href="#"><li><i class="fa fa-heart-o"></i>Liked Videos</li></a>
<a href="#"><li><i class="fa fa-indent"></i>My Music</li></a>
<a href="#"><li><i class="fa fa-indent"></i>Eminem</li></a>
<a href="#"><li><i class="fa fa-indent"></i>David Guetta</li></a>
</ul>
</div>
<div class="sve">
<div id="cover">
<div id="info">
<img src="https://i.imgur.com/GjLlmP6.jpg">
<div id="nick">Dino</div>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent eget nunc urna. Integer sed massa et est consequat lacinia sit amet nec eros. Phasellus massa magna, varius vitae pellentesque et, maximus eu nisl.</p>
</div>
</div>
<div id="toolsi">
<ul>
<a href="#"><li class="active">Home</li></a>
<a href="#"><li>Videos</li></a>
<a href="#"><li>Playlists</li></a>
<a href="#"><li>Discussions</li></a>
<a href="#"><li>About</li></a>
<a href="#"><li class="facebook"><i class="fa fa-facebook-official fa-2x"></i></li></a>
<a href="#"><li class="instagram"><i class="fa fa-instagram fa-2x"></i></li></a>
<a href="#"><li class="googleplus"><i class="fa fa-google-plus-square fa-2x"></i></li></a>
<a href="#"><li class="twitter"><i class="fa fa-twitter-square fa-2x"></i></li></a>
</ul>
<div id="subs">
<input type="button" value="Subscribe">
<span id="sub">839 418 <p>Subscribers</p></span>
</div>
</div>
<div id="kanali">
<ul>
<li id="title"><strong>Featured Channels</strong></li>
<li><img src="https://i.ytimg.com/i/RZoK7sezr5KRjk7BBjmH6w/mq1.jpg"><p>#RockMusic <i class="fa fa-check" id="kvaka"></i></p></li>
<li><img src="https://yt3.ggpht.com/-T7-tAkFbPOk/AAAAAAAAAAI/AAAAAAAAAAA/YE0M7XD3ZNM/s176-c-k-no/photo.jpg"><p>S.A.R.S.</p> <i class="fa fa-plus" id="plus"></i></p></li>
<li><img src="https://yt3.ggpht.com/-KjeWgxQlLV4/AAAAAAAAAAI/AAAAAAAAAAA/fMGm96CImAc/s46-c-k-no/photo.jpg"><p>HowToBasic</p> <i class="fa fa-check" id="kvaka"></i></p></li>
<li><img src="https://yt3.ggpht.com/-TrtEHOgcMFE/AAAAAAAAAAI/AAAAAAAAAAA/K547x_dy1bY/s176-c-k-no/photo.jpg"><p>Liverpool FC</p> <i class="fa fa-check" id="kvaka"></i></p></li>
<li><img src="https://yt3.ggpht.com/--n5ELY2uT-U/AAAAAAAAAAI/AAAAAAAAAAA/d9JvaIEpstw/s46-c-k-no/photo.jpg"><p>thenewboston</p> <i class="fa fa-plus" id="plus"></i></p></li>
</ul>
</div>
<div id="uploads">
<h1 id="title">Popular uploads</h1>
<div id="video">
<div id="slika">
<span id="pregledi">2, 299, 672, 978 views</span>
<span id="trajanje">4:13</span>
</div>
<a href="#"><h2>PSY - Gangam style</h2></a>
<span id="objavljen">Published 1 year ago</span>
</div>
<div id="video">
<div id="slika2">
<span id="pregledi">8, 372, 879 views</span>
<span id="trajanje2">12:28</span>
</div>
<a href="#"><h2>The best goalkeeper saves in 2014.</h2></a>
<span id="objavljen">Published 3 months ago</span>
</div>
<div id="video">
<div id="slika3">
<span id="pregledi">92,397 views</span>
<span id="trajanje3">6:33</span>
</div>
<a href="#"><h2>Merseyside Blind FC take part in special training session at Melwood</h2></a>
<span id="objavljen">Published 2 months ago</span>
</div>
</div>
<a href="#">
<div id="vel">
<div id="vrh">
<span id="lijevo">1, 531, 912 views</span>
<span id="desno">12:36</span>
</div>
<div id="dno">
<h1>Steven Gerrard - The best goals ever (1998-2015)</h1>
<p>Published 7 days ago</p>
</div>
<div id="ov">
<i class="fa fa-play fa-5x"></i>
<h1>Play video</h1>
</div>
</div>
</a>
<div id="interv">
<div id="traka">
<h1>Interviews</h1>
<input type="button" value="Play all">
</div>
<ul>
<li><div id="video">
<div id="slika4">
<span id="pregledi">52, 316 views</span>
<span id="trajanje3">5:00</span>
</div>
<a href="#"><h2>Adam Lallana interview Liverpool FC</h2></a>
<span id="objavljen">Published 3 months ago</span>
</div>
</li>
<li><div id="video">
<div id="slika5">
<span id="pregledi">21,397 views</span>
<span id="trajanje3">5:00</span>
</div>
<a href="#"><h2>Simon Mignolet interview Liverpool FC</h2></a>
<span id="objavljen">Published 4 months ago</span>
</div>
</li>
<li><div id="video">
<div id="slika6">
<span id="pregledi">142,396 views</span>
<span id="trajanje4">15:00</span>
</div>
<a href="#"><h2>Steven Gerrard interview Liverpool FC</h2></a>
<span id="objavljen">Published 2 months ago</span>
</div>
</li>
<li><div id="video">
<div id="slika7">
<span id="pregledi">19,878 views</span>
<span id="trajanje3">5:00</span>
</div>
<a href="#"><h2>Lazar Marković interviw Liverpool FC</h2></a>
<span id="objavljen">Published 2 months ago</span>
</div>
</li>
</li>
<li><div id="video">
<div id="slika8">
<span id="pregledi">42,267 views</span>
<span id="trajanje3">5:00</span>
</div>
<a href="#"><h2>Daniel Sturridge interview Liverpool FC</h2></a>
<span id="objavljen">Published 1 months ago</span>
</div>
</li>
</li>
<li><div id="video">
<div id="slika9">
<span id="pregledi">32,397 views</span>
<span id="trajanje3">5:00</span>
</div>
<a href="#"><h2>Raheem Sterling interview Liverpool FC</h2></a>
<span id="objavljen">Published 2 months ago</span>
</div>
</li>
</div>
</div>
</body>
@import url(https://fonts.googleapis.com/css?family=Lato:100,300,400,700);
*
{
margin: 0;
padding: 0;
}
body
{
background: #F7F8FA;
font-family: Lato;
}
.traka
{
background: #fff;
height: 85px;
width: 100%;
border-bottom: 1px solid #EBECEB;
position: fixed;
z-index: 100;
}
.traka .logo img
{
height: 35px;
margin-left: 60px;
margin-top: 25px;
padding-right: 50px;
border-right: 1px solid #EBECEB;
}
.traka input[type=search]
{
border: none;
outline: none;
width: 40%;
height: 40px;
font-size: 18px;
font-family: Lato;
font-weight: 300;
position: absolute;
margin-top: 25px;
margin-left: 30px;
border-bottom: 1px solid #EBECEB;
}
input[type=button]
{
background: #E21725;
border: none;
outline: none;
border-radius: 3px;
text-transform: uppercase;
color: white;
font-weight: 600;
font-size: 11px;
font-family: Lato;
padding-bottom: 10px;
padding-top: 10px;
padding-right: 20px;
padding-left: 20px;
border-bottom: 2px solid #CA131F;
}
input[type=button]:hover
{
background: #E21725;
}
input[type=button]:active
{
background: #CA131F;
}
.traka input[type=button]
{
float: right;
margin-right: 100px;
margin-top: 28px;
}
#menu
{
width: 270px;
height: 100%;
background: #fff;
float: right;
border-left: 1px solid #EBECEB;
}
#menu li
{
display: inline-block;
font-size: 20px;
color: #879099;
margin-top: 35px;
margin-left: 35px;
}
#poruke:after
{
content: '6';
background: #E21725;
color: white;
font-size: 10px;
padding: 4px;
padding-right: 6px;
padding-left: 6px;
position: absolute;
top: -12px;
border: 2px solid white;
border-radius: 100%;
right: -11px;
font-family: Lato;
font-weight: normal;
}
#notifikacije:after
{
content: '9';
background: #E21725;
color: white;
font-size: 10px;
padding: 4px;
padding-right: 6px;
padding-left: 6px;
position: absolute;
top: -12px;
border: 2px solid white;
border-radius: 100%;
right: -11px;
font-family: Lato;
font-weight: normal;
}
#menu img
{
height: 50px;
width: 50px;
border-radius: 100%;
position: absolute;
top: 18px;
right: 50px;
}
#down
{
margin-left: 75px;
}
.sve
{
background: white;
height: 220%;
width: 82%;
position: relative;
float: right;
border-left: 1px solid #EBECEB;
}
.strana
{
width: 18%;
height: 100%;
position: fixed;
float: left;
z-index: 99;
}
.strana li
{
color: #A09F9D;
list-style: none;
font-family: Lato;
font-weight: bold;
padding-top: 10px;
padding-bottom: 10px;
padding-left: 5px;
padding-right: 10px;
transition: .1s all ease;
}
.strana ul
{
margin-top: 120px;
margin-left: 40px;
}
.strana ul:nth-child(2)
{
margin-top: 40px;
margin-left: 40px;
}
#title i
{
margin-left: 57px;
color: #A09F9D;
}
a
{
text-decoration: none;
color: #A09F9D;;
}
#title
{
font-size: 14px;
color: #E21725;
text-transform: uppercase;
font-weight: bold;
font-family: Arial;
}
#title:hover
{
background: transparent;
}
.strana li:hover
{
background: #E21725;
color: #fff;
}
.strana li:hover i
{
color: #fff;
}
.strana i
{
margin-right: 20px;
}
#cover
{
height: 400px;
width: 100%;
background: url("https://i.imgur.com/jp5slG3.jpg");
background-size: 100%;
background-position: 0px -180px;
}
#info
{
background: rgba(0,0,0,0.3);
height: 100%;
width: 271px;
float: right;
text-align: center;
}
#info img
{
height: 100px;
width: 100px;
border-radius: 100%;
margin: 10px auto;
margin-top: 100px;
}
#nick
{
font-family: Lato;
font-weight: 100;
color: white;
font-size: 30px;
text-align: center;
width: 100%;
}
#info p
{
font-family: Lato;
color: white;
font-weight: 300;
margin: 10px auto;
}
#toolsi
{
height: 65px;
width: 100%;
background: #fff;
border-bottom: 1px solid #EBECEB;
position: relative;
}
#toolsi li
{
display: inline-block;
letter-spacing: 1px;
text-transform: uppercase;
font-size: 11px;
font-family: Arial;
font-weight: bold;
padding-bottom: 8px;
padding-left: 10px;
padding-right: 10px;
margin-right: 10px;
transition: .1s ease all;
}
.active
{
border-bottom: 2px solid #E21725;
color: rgba(0,0,0,0.7);
}
#toolsi ul
{
margin-left: 35px;
line-height: 4;
}
#subs
{
width: 270px;
height: 100%;
background: #fff;
border-left: 1px solid #EBECEB;
position: absolute;
top: 0;
right: 0;
}
#subs input[type=button]
{
margin: 17px;
}
#sub
{
color: #A09F9D;
font-size: 15px;
text-align: center;
position: absolute;
margin: 17px;
margin-left: 30px;
font-weight: 600;
}
#sub p
{
font-size: 10px;
text-transform: uppercase;
}
#kanali
{
height: 320px;
width: 270px;
border-left: 1px solid #EBECEB;
background: #F7F8FA;
float: right;
position: relative;
}
#kanali li
{
list-style: none;
margin-top: 20px;
}
#kanali p
{
vertical-align:10px;
display: inline;
margin-left: 15px;
color: #A09F9D;
font-size: 13px;
font-family: Arial;
font-weight: bold;
}
#kanali ul
{
margin: 30px;
}
#kanali img
{
height: 30px;
width: 30px;
border-radius: 100%;
}
#kanali i
{
padding: 5px;
height: 10px;
width: 10px;
color: white;
border-radius: 2px;
font-size: 10px;
margin-left: 30px;
margin-top: 3px;
position: absolute;
cursor: pointer;
right: 50px;
}
#kvaka
{
background:#E21725;
}
#plus
{
background: #818B94;
}
#uploads
{
height: 700px;
width: 270px;
border-left: 1px solid #EBECEB;
background: #F7F8FA;
top: 320px;
position: relative;
border-top: 1px solid #EBECEB;
float: right;
margin-right: -271px;
}
.facebook
{
margin-left: 60px;
}
.facebook:hover
{
color: #3b5998;
}
.instagram:hover
{
color: #3f729b;
}
.googleplus:hover
{
color: #dd4b39;
}
.twitter:hover
{
color: #55acee;
}
#uploads h1
{
margin: 30px;
}
#video
{
height: 195px;
width: 200px;
margin: 20px;
}
#video img
{
height: 120px;
width: 195px;
border-radius: 10px;
position: relative;
}
#video h2
{
font-size: 15px;
font-family: Lato;
margin-top: 10px;
transition: .1s ease all;
color: #293543;
font-weight: 450;
margin-bottom: 5px;
}
#objavljen
{
font-size: 11px;
color: #A09F9D;
}
#slika
{
height: 120px;
width: 195px;
background: url("https://i.ytimg.com/vi/9bZkp7q19f0/mqdefault.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika2
{
height: 120px;
width: 195px;
background: url("https://metrouk2.files.wordpress.com/2013/01/ay102122611arsenals-polish.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika3
{
height: 120px;
width: 195px;
background: url("https://i.ytimg.com/vi_webp/qe8A61_5oek/mqdefault.webp")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika4
{
height: 120px;
width: 195px;
background: url("http://assets.lfcimages.com/uploads/3333__2665__lallana1000a_517X310.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika5
{
height: 120px;
width: 195px;
background: url("http://i.ytimg.com/vi/-qNoH9b-THM/maxresdefault.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika6
{
height: 120px;
width: 195px;
background: url("http://assets1.lfcimages.com/uploads/1905__7361__gerrardinterview1000_517X310.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika7
{
height: 120px;
width: 195px;
background: url("http://footballtube.r.worldssl.net/img/video/lazar-markovic--first-interview-for-liverpool-fc.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika8
{
height: 120px;
width: 195px;
background: url("http://i.ytimg.com/vi/rNyiqIokbgg/maxresdefault.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika9
{
height: 120px;
width: 195px;
background: url("http://i1.ytimg.com/vi/x7tTvQy76M0/hqdefault.jpg")no-repeat;
background-size: 120%;
border-radius: 7px;
}
#slika8 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika9 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika2 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika3 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika4 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika5 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika6 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#slika7 span
{
color: white;
background: rgba(0,0,0,0.7);
border-radius: 15px;
font-family: Lato;
font-weight: 500;
padding: 7px;
font-size: 11px;
}
#pregledi
{
margin-left: 3px;
line-height: 4;
}
#trajanje
{
margin-left: 28px;
}
#trajanje2
{
margin-left: 45px;
}
#trajanje3
{
margin-left: 70px;
}
#trajanje4
{
margin-left: 58px;
}
#video h2:hover
{
color: #E21725;
}
#vel
{
height: 400px;
width: 70%;
background: url("http://www.lostivalepensante.it/wp-content/uploads/ay102894607epa03566911-live.jpg")no-repeat;
background-size: 100%;
margin: 25px;
margin-top: 40px;
border-radius: 4px;
position: relative;
}
#vrh
{
height: 100px;
width: 100%;
color: white;
top: 20px;
left: 50px;
position: absolute;
}
#vrh span
{
background: rgba(0,0,0,0.5);
padding: 10px;
border-radius: 25px;
}
#lijevo
{
float: left;
}
#desno
{
margin-left: 450px;
}
#dno
{
height: 120px;
width: 100%;
position: absolute;
bottom: 0;
transition: .1s all ease;
border-radius: 0px 0px 4px 4px;
color: white;
background: -moz-linear-gradient(top, rgba(0,0,0,0) 0%, rgba(0,0,0,0.65) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(0,0,0,0)), color-stop(100%,rgba(0,0,0,0.65))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(top, rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(top, rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%); /* IE10+ */
background: linear-gradient(to bottom, rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00000000', endColorstr='#a6000000',GradientType=0 ); /* IE6-9 */
}
#dno h1
{
width: 70%;
font-family: Lato;
font-weight: 300;
font-size: 30px;
margin: 30px;
}
#dno p
{
position: absolute;
right: 10;
bottom: 10;
font-family: Lato;
font-weight: 300;
}
#vel:hover #dno
{
display: none;
}
#vel:hover #vrh
{
display: none;
}
#ov
{
height: 100%;
width: 100%;
position: absolute;
background: rgba(226,23,37, 0.7);
display: none;
transition: .3s all ease;
}
#ov i
{
margin-top: 160px;
margin-left: 320px;
color: #fff;
text-align: center;
text-shadow: 1px 3px 5px #000000;
border-radius: 4px;
}
#vel:hover #ov
{
display: block;
}
#ov h1
{
width: 97%;
font-family: Lato;
font-weight: 300;
margin-top: 20px;
font-size: 30px;
text-align: center;
color: white;
}
#interv
{
position: relative;
height: 500px;
width: 74%;
margin: 25px;
}
#traka
{
position: absolute;
top: 0;
width: 100%;
height: 45px;
}
#interv h1
{
font-size: 14px;
color: #E21725;
text-transform: uppercase;
font-family: Arial;
font-weight: bold;
line-height: 3;
}
#traka input[type=button]
{
right: 0;
top: 0;
position: absolute;
font-size: 10px;
}
#interv li
{
display: inline-block;
margin-top: -15px;
}
#interv ul
{
position: absolute;
left: -15px;
top: 50px;
}
Also see: Tab Triggers