CSS Input with width: 100% goes outside parent'

问题:

I am trying to make a login form constituted of two input fields with an inset padding, but those two fields always end up exceeding its parent's boundaries; the issue stems from the added inset padding. What could be done in order to rectify this issue?

JSFiddle snippet: http://jsfiddle.net/4x2KP/

N.B.: The code may not be at its cleanest. For instance, the span element that encapsulates the text inputs may not be needed at all.

    #mainContainer {
    	line-height: 20px;
    	font-family: "Helvetica Neue",Helvetica,Arial,sans-serif;
        background-color: rgba(0,50,94,0.2);
    	margin: 20px auto;
    	display: table;
    	-moz-border-radius: 15px;
    	border-style: solid;
    	border-color: rgb(40, 40, 40);
    	border-radius: 2px 5px 2px 5px / 5px 2px 5px 2px;
    	border-radius: 2px;
    	border-radius: 2px 5px / 5px;
    	box-shadow: 0 5px 10px 5px rgba(0,0,0,0.2);
    }
    
    .loginForm {
    	width: 320px;
    	height: 250px;
    	padding: 10px 15px 25px 15px;
    	overflow: hidden;
    }
    
    .login-fields > .login-bottom input#login-button_normal {
    	float: right;
    	padding: 2px 25px;
    	cursor: pointer;
    	margin-left: 10px;
    }
    
    .login-fields > .login-bottom input#login-remember {
    	float: left;
    	margin-right: 3px;
    }
    
    .spacer {
    	padding-bottom: 10px;
    }
    
    /* ELEMENT OF INTEREST HERE! */
    input[type=text],
    input[type=password] {
        width: 100%;
    	height: 20px;
    	padding: 5px 10px;
    	background-color: rgb(215, 215, 215);
        line-height: 20px;
        font-size: 12px;
        color: rgb(136, 136, 136);
        border-radius: 2px 2px 2px 2px;
        border: 1px solid rgb(114, 114, 114);
    	box-shadow: 0 1px 0 rgba(24, 24, 24,0.1);
    }
    
    input[type=text]:hover,
    input[type=password]:hover,
    label:hover ~ input[type=text],
    label:hover ~ input[type=password] {
     	background:rgb(242, 242, 242) !important;
    }
    
    input[type=submit]:hover {
      box-shadow:
        inset 0 1px 0 rgba(255,255,255,0.3),
        inset 0 -10px 10px rgba(255,255,255,0.1);
    }

    <div id="mainContainer">
        <div id="login" class="loginForm">
            <div class="login-top">
            </div>
            <form class="login-fields" onsubmit="alert('test'); return false;">
                <div id="login-email" class="login-field">
                    <label for="email" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">E-mail address</label>
                    <span><input name="email" id="email" type="text"></input></span>
                </div>
                <div class="spacer"></div>
                <div id="login-password" class="login-field">
                    <label for="password" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">Password</label>
                    <span><input name="password" id="password" type="password"></input></span>
                </div>
                <div class="login-bottom">
                    <input type="checkbox" name="remember" id="login-remember"></input>
                    <label for="login-remember" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">Remember my email</label>
                    <input type="submit" name="login-button" id="login-button_normal" style="cursor: pointer" value="Log in"></input>
                </div>
            </form>
        </div>
    </div>

回答1:

Use the CSS definition box-sizing:border-box to prevent padding from affecting an element's width or height. See documentation for box-sizing. You may also want to check the browser compatibility of box-sizing (IE8+).

border-box : The width and height properties include the padding and border, but not the margin... Note that padding and border will be inside of the box.

input[type=text],
input[type=password] {
    box-sizing : border-box;
}

EDIT: At the time of this edit, no prefixes are necessary for box-sizing. See shouldiprefix.com.

#mainContainer {
  line-height: 20px;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  background-color: rgba(0, 50, 94, 0.2);
  margin: 20px auto;
  display: table;
  -moz-border-radius: 15px;
  border-style: solid;
  border-color: rgb(40, 40, 40);
  border-radius: 2px 5px 2px 5px / 5px 2px 5px 2px;
  border-radius: 2px;
  border-radius: 2px 5px / 5px;
  box-shadow: 0 5px 10px 5px rgba(0, 0, 0, 0.2);
}
.loginForm {
  width: 320px;
  height: 250px;
  padding: 10px 15px 25px 15px;
  overflow: hidden;
}
.login-fields > .login-bottom input#login-button_normal {
  float: right;
  padding: 2px 25px;
  cursor: pointer;
  margin-left: 10px;
}
.login-fields > .login-bottom input#login-remember {
  float: left;
  margin-right: 3px;
}
.spacer {
  padding-bottom: 10px;
}
input[type=text],
input[type=password] {
  width: 100%;
  height: 30px;
  padding: 5px 10px;
  background-color: rgb(215, 215, 215);
  line-height: 20px;
  font-size: 12px;
  color: rgb(136, 136, 136);
  border-radius: 2px 2px 2px 2px;
  border: 1px solid rgb(114, 114, 114);
  box-shadow: 0 1px 0 rgba(24, 24, 24, 0.1);
  box-sizing: border-box;
}
input[type=text]:hover,
input[type=password]:hover,
label:hover ~ input[type=text],
label:hover ~ input[type=password] {
  background: rgb(242, 242, 242);
  !important;
}
input[type=submit]:hover {
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.3), inset 0 -10px 10px rgba(255, 255, 255, 0.1);
}
.login-top {
  height: auto;/*85px;*/
}
.login-bottom {
  padding: 35px 15px 0 0;
}

<div id="mainContainer">
  <div id="login" class="loginForm">
    <div class="login-top">
    </div>
    <form class="login-fields" onsubmit="alert('test'); return false;">
      <div id="login-email" class="login-field">
        <label for="email" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">E-mail address</label>
        <span><input name="email" id="email" type="text" /></span>
      </div>
      <div class="spacer"></div>
      <div id="login-password" class="login-field">
        <label for="password" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">Password</label>
        <span><input name="password" id="password" type="password" /></span>
      </div>
      <div class="login-bottom">
        <input type="checkbox" name="remember" id="login-remember" />
        <label for="login-remember" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">Remember my email</label>
        <input type="submit" name="login-button" id="login-button_normal" style="cursor: pointer" value="Log in" />
      </div>
    </form>
  </div>
</div>

---

Alternatively, rather than adding padding to the <input> elements themselves, style the <span> elements wrapping the inputs. That way, the <input> elements can be set to width:100% without being affected by any additional padding. Example below:

#login-form {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  background-color: rgba(0, 50, 94, 0.2);
  margin: 20px auto;
  padding: 10px 15px 25px 15px;
  border: 4px solid rgb(40, 40, 40);
  box-shadow: 0 5px 10px 5px rgba(0, 0, 0, 0.2);
  border-radius: 2px;
  width: 320px;
}
label span {
  display: block;
  padding: .3em 1em;
  background-color: rgb(215, 215, 215);
  border-radius: .25em;
  border: 1px solid rgb(114, 114, 114);
  box-shadow: 0 1px 0 rgba(24, 24, 24, 0.1);
  margin: 0 0 1em;
}
label span:hover {
  background: rgb(242, 242, 242);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.3), inset 0 -10px 10px rgba(255, 255, 255, 0.1);
}
input[type=text],
input[type=password] {
  background: none;
  border: none;
  width: 100%;
  height: 2em;
  line-height: 2em;
  font-size: 12px;
  color: rgb(136, 136, 136);
  outline: none;
}
.login-bottom {
  margin: 2em 1em 0 0;
}
input#login-button {
  float: right;
  padding: 2px 25px;
}
input#login-remember {
  float: left;
  margin-right: 3px;
}

<form id="login-form">
  <label>E-mail address
    <span><input name="email" type="text" /></span>
  </label>
  <label>Password
    <span><input name="password" type="password" /></span>
  </label>
  <div class="login-bottom">
    <label>
      <input type="checkbox" name="remember" id="login-remember" />Remember my email
    </label>
    <input type="submit" name="login-button" id="login-button" value="Log in" />
  </div>
</form>

回答2:

If all above fail, try setting the following properties for your input, to have it take max space but not overflow:

input {
    min-width: 100%;
    max-width: 100%;
}

回答3:

The other answers seem to tell you to hard-code the width or use a browser-specific hack. I think there is a simpler way.

By calculating the width and subtracting the padding (which causes the field overlap). The 20px comes from 10px for left padding and 10px for right padding.

input[type=text],
input[type=password] {
    ...
    width: calc(100% - 20px);
}

回答4:

Padding is added to the overall width. Because your container has a pixel width, you are better off giving the inputs a pixel width too, but remember to remove the padding and border from the width you set to avoid the same issue.

回答5:

Try changing the box-sizing to border-box. The padding is adding to width of your input elements.

See Demo here

CSS

input[type=text],
input[type=password] {
    width: 100%;
    margin-top: 5px;
    height: 25px;
    ...
}

input {
    box-sizing: border-box;
}

+box-sizing

回答6:

I tried these solutions but never got a conclusive result. In the end I used proper semantic markup with a fieldset. It saved having to add any width calculations and any box-sizing.

It also allows you to set the form width as you require and the inputs remain within the padding you need for your edges.

In this example I have put a border on the form and fieldset and an opaque background on the legend and fieldset so you can see how they overlap and sit with each other.

<html>
  <head>
  <style>
    form {
      width: 300px;
      margin: 0 auto;
      border: 1px solid;
    }
    fieldset {
      border: 0;
      margin: 0;
      padding: 0 20px 10px;
      border: 1px solid blue;
      background: rgba(0,0,0,.2);
    }
    legend {
      background: rgba(0,0,0,.2);
      width: 100%;
      margin: 0 -20px;
      padding: 2px 20px;
      color: $col1;
      border: 0;
    }
    input[type="email"],
    input[type="password"],
    button {
      width: 100%;
      margin: 0 0 10px;
      padding: 0 10px;
    }
    input[type="email"],
    input[type="password"] {
      line-height: 22px;
      font-size: 16px;
    }
    button {
    line-height: 26px;
    font-size: 20px;
    }
  </style>
  </head>
  <body>
  <form>
      <fieldset>
          <legend>Log in</legend>
          <p>You may need some content here, a message?</p>
          <input type="email" id="email" name="email" placeholder="Email" value=""/>
          <input type="password" id="password" name="password" placeholder="password" value=""/>
          <button type="submit">Login</button>
      </fieldset>
  </form>
  </body>
</html>

回答7:

Padding is essentially added to the width, therefore when you say width:100% and padding: 5px 10px you're actually adding 20px to the 100% width.

回答8:

Do you want the input fields to be centered? A trick to center elements: specify the width of the element and set the margin to auto, eg:

margin : 0px auto;
width:300px

A link to your updated fiddle:

http://jsfiddle.net/4x2KP/5/

回答9:

You also have an error in your css with the exclamation point in this line:

background:rgb(242, 242, 242);!important;

remove the semi-colon before it. However, !important should be used rarely and can largely be avoided.