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<!DOCTYPE html>
<html lang="en-US">
<!-- Mirrored from www.w3schools.com/default.asp by HTTrack Website Copier/3.x [XR&CO'2014], Wed, 21 Dec 2022 09:29:05 GMT -->
<head>
<title>W3Schools Online Web Tutorials</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="Keywords" content="HTML, Python, CSS, SQL, JavaScript, How to, PHP, Java, C, C++, C#, jQuery, Bootstrap, Colors, W3.CSS, XML, MySQL, Icons, Node.js, React, Graphics, Angular, R, AI, Git, Data Science, Code Game, Tutorials, Programming, Web Development, Training, Learning, Quiz, Exercises, Courses, Lessons, References, Examples, Learn to code, Source code, Demos, Tips, Website">
<meta name="Description" content="Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more.">
<meta property="og:image" content="https://www.w3schools.com/images/w3schools_logo_436_2.png">
<meta property="og:image:type" content="image/png">
<meta property="og:image:width" content="436">
<meta property="og:image:height" content="228">
<meta property="og:title" content="W3Schools Free Online Web Tutorials">
<meta property="og:description" content="W3Schools offers free online tutorials, references and exercises in all the major languages of the web. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more.">
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<link rel="stylesheet" href="lib/w3schools30.css">
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var searchFromBox = false;
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<style>
/* Customize w3schools23.css */
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#nav_references,
#nav_exercises {
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#nav_tutorials h3,
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div.cse .gsc-control-cse,
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/* Customize W3.CSS */
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z-index: 4;
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color:white!important;
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right:0!important;
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h1,
.w3-jumbo {
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div.cse .gsc-control-cse,
div.gsc-control-cse {
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margin-top: 1em;
margin-bottom: 1em;
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margin-bottom: 1em;
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width: 60px;
font-size:14px;
padding: 5px;
position: absolute;
left:-20px;
top:-10px;
text-align: center;
color:black;
border-radius:25px;
-ms-transform: rotate(-20deg); /* IE 9 */
transform: rotate(-20deg);
}
.ws-yellow-hover:hover {
background-color:#fff080!important;
color:black!important;
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background-color:#ffb3bb!important;
color:black!important;
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font-size:11px;
font-weight:bold;
padding:3px 10px;
margin-left:3px;
text-align: center;
color:black;
border-radius:25px;
border:1px solid black;
position:relative;
top:-2px;
background-color:white;
}
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z-index:7!important;
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.ribbon-topnav {
display: none !important;
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}
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display: none !important;
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#darkmodemenu {
padding:5px 10px 10px 9px;
}
}
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.ws-hide-1080 {
display: none !important;
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border-bottom-right-radius:4px;
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height: 80px;
position: absolute;
top:-6px;
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margin-left:-25px;
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margin-top:73px;
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#howto_iframe {
height: 320px;
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@media screen and (max-width: 700px) {
#howto_iframe {
height: 280px;
}
.codeeditorbr-input {
margin-left: 15px;
}
.vl-howto {
height:45px;
}
.vl-howtobtn {
margin-top:37px;
}
}
@media screen and (max-width:584px) {
#howto_iframe {
height: 245px;
}
}
@media screen and (max-width:500px) {
#howto_iframe {
height: 215px;
}
}
@media screen and (max-width:450px) {
#howto_iframe {
height: 203px;
}
}
.codeeditorbr-container {
border-top-left-radius: 4px;
border-top-right-radius: 4px;
}
.codeeditorbr-row {
padding: 10px;
background: #f1f1f1;
border-top-left-radius: 4px;
border-top-right-radius: 4px;
}
.codeeditorbr-column {
float: left;
}
.codeeditorbr-left {
width: 20%;
}
.codeeditorbr-middle {
width: 80%;
}
@media screen and (max-width: 800px) {
.codeeditorbr-left {
width: 24%;
}
.codeeditorbr-middle {
width: 76%;
}
}
.codeeditorbr-row:after {
content: "";
display: table;
clear: both;
}
.codeeditorbr-dot {
margin-top: 5px;
height: 15px;
width: 15px;
background-color: #bbb;
border-radius: 50%;
display: inline-block;
margin-left: 3px;
}
.codeeditorbr-input {
width: 80%;
border-radius: 3px;
border: none;
background-color: white;
margin-top: -8px;
height: 22px;
color: #666;
font-size: 14px;
padding: 5px;
}
.hover-yellow:hover {
background-color: #fff080 !important;
color: black !important;
}
.codeeditorbr-tablink {
font-size: 17px;
font-family: 'Source Sans Pro', sans-serif;
border: none;
display: inline-block;
padding: 6px 18px;
vertical-align: middle;
overflow: hidden;
text-decoration: none;
color: inherit;
text-align: center;
cursor: pointer;
white-space: nowrap;
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
color: #ffffff;
}
.codeeditorbr-tablink:hover {
background-color: #E7E9EB !important
}
.hover-yellow:hover {
background-color:#fff080!important;
color:black!important;
}
#bgcodeimg {
background: #282A35 url("about/w3codes.png") no-repeat fixed center;
}
#bgcodeimg2 {
background: #282A35 url("spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg") no-repeat fixed center;
}
form.example {
position:relative;
}
form.example input[type=text] {
padding: 10px;
font-size: 17px;
border: 1px solid #282A35;
border-radius:25px;
float: left;
width: 80%;
padding-left:25px;
background: white;
border-top-right-radius:0;
border-bottom-right-radius:0;
border-right:0;
border-right: 1px solid #04AA6D;
outline:0;
}
form.example button {
border-radius:25px;
float: left;
width: 20%;
padding: 10px;
background:#04AA6D;
color: white;
font-size: 17px;
border: 1px solid #282A35;
border-left: none;
cursor: pointer;
border-top-left-radius:0;
border-bottom-left-radius:0;
}
form.example button:hover {
background: #059862;
color: white;
}
form.example::after {
content: "";
clear: both;
display: table;
}
#listofsearchresults {
display:none;
position:absolute;
//border:1px solid #000;
background-color:#282A35;
background-color:#fff;
color:#000;
width:80%;
top:47px;
border-left: 1px solid #282A35;
border-right: 1px solid #282A35;
border-bottom: 1px solid #282A35;
text-align:left;
}
#listofsearchresults a {
background-color:#e2e3e9;
background-color:#fff;
color:#777;
text-decoration:none;
display:block;
padding:10px 30px;
width:100%;
opacity:0.95;
}
#listofsearchresults a:hover {
color:#000;
opacity:1;
}
.span_search {
background-color:#ffecee;
}
.search_active {
background-color:#ffecee!important;
color:#000!important;
}
.search_active .span_search {
background-color:#ffccd1;
}
.learntocodeh1 {
font-size:70px;
font-weight:700;
}
.learntocodeh3 {
color:#FFC0C7;
font-weight:700;
margin-top:30px!important;
font-size:23px;
}
.learntocodecontent {
padding-left:90px;
padding-right:90px;
}
@media screen and (max-width: 600px) {
.learntocodeh1 {
font-size:50px!important;
}
.learntocodeh3 {
font-size:21px!important;
}
.learntocodecontent {
padding-left:35px;
padding-right:35px;
}
form.example input[type=text],form.example button {
font-size: 16px;
}
form.example input[type=text] {
padding-left:16px;
}
}
@media screen and (max-width: 1006px) and (min-width: 992px) {
.ws-hide-special {
display:none;
}
}
.grey-color {
background-color: #E7E9EB;
color: #000;
}
body.darkpagetheme .grey-color {
background-color: #38444d;
color: #ddd;
}
body.darkpagetheme .bar-icon-hover:hover,body.darkpagetheme .fa-logo:hover {
background-color: #1d2a35!important;
color:#059862!important;
}
table.gstl_50 {/*google search suggestions*/
color:#000;
}
.topnavmain_pro {
background-color:#282A35;
color:#fff;
}
body.darkpagetheme .topnavmain_pro {
background-color:#fff;
color:#000;
}
.pro-caption {
padding: 78px 35px 96px 35px;
text-align: center
}
.pro-caption h1 {
font-weight: 700;
font-size: 52px;
line-height: 55px;
padding-top: 11px;
padding-bottom: 20px;
font-family: Source Sans Pro;
color: #fff;
margin: 0
}
.pro-caption h3 {
font-size: 25px;
color: #FFC0C7;
margin:19px 0;
}
.pro-caption li {
font-size:20px;
line-height:36px;
text-align:left;
list-style-type:none;
}
@media screen and (max-width:620px) {
.pro-caption {padding: 70px 15px 70px 15px;}
.pro-caption h1 {font-size:50px;}
.pro-caption h3 {font-size:24px;}
.pro-caption li {font-size:18px;}
}
@media screen and (max-width:550px) {
.pro-caption h1 {font-size:40px;}
.pro-caption h3 {font-size:24px;}
.pro-caption li {font-size:18px;}
}
</style>
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-->
<a class="w3-bar-item w3-button bar-icon-hover w3-right w3searchbtntopnav" href="javascript:void(0)" style="padding-top:24px;padding-bottom:24px;padding-left:12px;padding-right:12px;margin-right:8px" onclick="gSearch(this)" title='Search W3Schools' id="nav_search_btn"><i class='fa'></i></a>
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<div id="darkmodemenu" class="w3-white w3-hide-small" onmouseover="mouseoverdarkicon()" onmouseout="mouseoutofdarkicon()">
<input id="radio_darkpage" type="checkbox" name="radio_theme_mode" onclick="click_darkpage()"><label for="radio_darkpage"> Dark mode</label>
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<div class="w3-container w3-padding-32">
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