[html] How to expand textarea width to 100% of parent (or how to expand any HTML element to 100% of parent width)?

How to expand textarea width to 100% of parent?

I try width 100% but it is not works it expands to 100% of page what crash layout.

Here the question in visual way.

Please provide some hints.

I would do something like this:

HTML:

<div class="wrapper">
    <div class="side">sidebar here</div>
    <div class="main">
        <textarea class="taclass"></textarea>
    </div>
</div><!--/ wrapper -->

CSS:

.wrapper{
    display: block;
    width: 100%;
    overflow: hidden;
}
.side{
    float:left;
    width:20%;
}
.main{
    float:right;
    width:80%;
}
.taclass{
    display:block;
    width:100%;
    padding:2%;
    -webkit-box-sizing: border-box;
       -moz-box-sizing: border-box;
            box-sizing: border-box;
}

Try this..Add this in your page

<style>
textarea
{
width:100%;
}
</style>

HTML:

<div id="left"></div>
<div id="content">
        <textarea cols="2" rows="10" id="rules"></textarea>
</div>

CSS:

body{
    width:100%;
    border:1px solid black;
    border-radius:5px;

}
#left{
    width:20%;
height:400px;
    float:left;
    border: 1px solid black;
    display:block;
}
#content{
    width:78%;
    height:400px;
    float:left;
    border:1px solid black;
    text-align:center;
}
textarea
{
   margin-top:100px;
    width:98%;
}

DEMO: HERE

Add the css

  <style type="text/css">
    textarea
    {

        border:1px solid #999999
        width:99%;
        margin:5px 0;
        padding:1%;
    }
</style>

The box model is something every web-developer should know about. working with percents for sizes and pixels for padding/margin just doesn't work. There always is a resolution at which it doesn't look good (e.g. giving a width of 90% and a padding/margin of 10px in a div with a width of under 100px).

Check this out (using micro.pravi's code): http://jsbin.com/umeduh/2

<div id="container">
    <div class="left">
        <div class="content">
            left
        </div>
    </div>
    <div class="right">
        <div class="content">
            right
            <textarea>Check me out!</textarea>
        </div>
    </div>
</div>

The <div class="content"> are there so you can use padding and margin without screwing up the floats.

this is the most important part of the CSS:

textarea {
    display: block;
    width: 100%;
    -webkit-box-sizing: border-box;
       -moz-box-sizing: border-box;
            box-sizing: border-box;
}

You need to define width of the div containing the textarea and when you declare textarea, you can then set .main > textarea to have width: inherit.

Note: .main > textarea means a <textarea> inside of an element with class="main".

Here is the working solution

The HTML:

<div class="wrapper">
  <div class="left">left</div>
  <div class="main">
    <textarea name="" cols="" rows=""></textarea>
  </div>
</div>

The CSS:

.wrapper {
  display: table;
  width: 100%;
}

.left {
  width: 20%;
  background: #cccccc;
  display: table-cell;
}

.main {
  width: 80%;
  background: gray;
  display: inline;
}

.main > textarea {
  width: inherit;
}