How to make a header ribbon responsive - html

Question

I have the following JSFiddle: http://jsfiddle.net/eotamvwy/
HTML:
<div class="infobox-container">
<div class="triangle-l"></div>
<div class="triangle-r"></div>
<div class="infobox">
<h3><span>This is the Header</span></h3>
<p>This is the content of the infobox.<p/>
</div>
</div>
How can I modify the CSS so that it is responsive?
I have a div which has the following style:
width: 98%
padding: 0 1% 0 1%
I want to insert the infobox-container inside and stretch it 100% and resize based on the above div.

Answer 1

Use percentage units for responsiveness and for triangles you don't need extra elements, you could use :after and :before :pseudo-elements on .infobox h3.
Updated Fiddle
body {
width: 100%;
margin: 0;
}
.main-container {
width: 98%;
padding: 0 1% 0 1%;
text-align: center;
}
.infobox-container {
position: relative;
display: inline-block;
margin: 0;
padding: 0;
width: 100%;
}
.infobox {
width: 80%;
padding: 10px 5px 5px 5px;
margin: 10px;
position: relative;
z-index: 1;
-webkit-border-radius: 2px;
-moz-border-radius: 2px;
border-radius: 2px;
-webkit-box-shadow: 0px 0px 3px rgba(0, 0, 0, 0.55);
-moz-box-shadow: 0px 0px 3px rgba(0, 0, 0, 0.55);
box-shadow: 0px 0px 3px rgba(0, 0, 0, 0.55);
background: #424242;
background-image: -webkit-gradient(linear, left top, left bottom, from(#6a6b6b), to(#424242));
background-image: -moz-linear-gradient(top, #6a6a6a, #424242);
color: #fff;
font-size: 90%;
}
.infobox h3 {
position: relative;
width: calc(100% + 22px);
color: #fff;
padding: 10px 5px;
margin: 0;
left: -15px;
-webkit-box-shadow: 0px 0px 3px rgba(0, 0, 0, 0.55);
-moz-box-shadow: 0px 0px 3px rgba(0, 0, 0, 0.55);
box-shadow: 0px 0px 3px rgba(0, 0, 0, 0.55);
background: #3198dd;
background-image: -webkit-gradient(linear, left top, left bottom, from(#33acfc), to(#3198dd));
background-image: -moz-linear-gradient(top, #33acfc, #3198dd);
font-size: 160%;
text-align: center;
text-shadow: #2187c8 0 -1px 1px;
font-weight: bold;
}
.infobox h3:before,
.infobox h3:after {
content: '';
border-color: transparent #2083c2 transparent transparent;
border-style: solid;
border-width: 12px;
height: 0;
width: 0;
position: absolute;
left: -12px;
top: 100%;
transform: translateY(-50%);
z-index: -1;
/* displayed under infobox */
}
.infobox h3:after {
border-color: transparent transparent transparent #2083c2;
left: 100%;
margin-left: -12px;
}
.infobox a {
color: #35b0ff;
text-decoration: none;
border-bottom: 1px dotted transparent;
}
.infobox a:hover,
.infobox a:focus {
text-decoration: none;
border-bottom: 1px dotted #35b0ff;
}
<div class="main-container">
<div class="infobox-container">
<div class="infobox">
<h3><span>This is the Header</span></h3>
<p>This is the content of the infobox.</p>
</div>
</div>
</div>

Answer 2

If you want this header ribbon to be responsive, you need to get away from using fixed-widths and instead combine width:100%; and max-width: 270px; (or whatever).
When you define the width attribute to be 270px, you are telling the browser you want this particular element to have both a minimum and maximum width of 270px. If you are thinking responsively, what you actually want is for your element to expand as much as possible (width:100%), but to max-out at 270px (max-width: 270px;).
Thats the responsive bit.
What you are actually after is something closer to this:
http://jsfiddle.net/TheIronDeveloper/eotamvwy/3/
* {
box-sizing: border-box;
}
.infobox-container {
position: relative;
display: block;
margin: 0;
padding: 0;
max-width: 500px;
width: 100%;
}
.infobox {
padding: 3em 5px 5px;
margin:10px;
position: relative;
z-index: 90;
-webkit-border-radius: 2px;
-moz-border-radius: 2px;
border-radius: 2px;
-webkit-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
-moz-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
background: #424242;
background-image: -webkit-gradient(linear, left top, left bottom, from(#6a6b6b), to(#424242));
background-image: -moz-linear-gradient(top,#6a6a6a,#424242);
color: #fff;
font-size: 90%;
}
.infobox-ribbon {
position: absolute;
top: 10px;
width: 100%;
color: #fff;
padding: 10px 5px;
margin: 0;
z-index: 100;
-webkit-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
-moz-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
background: #3198dd;
background-image: -webkit-gradient(linear, left top, left bottom, from(#33acfc), to(#3198dd));
background-image: -moz-linear-gradient(top,#33acfc,#3198dd);
font-size: 160%;
text-align: center;
text-shadow: #2187c8 0 -1px 1px;
font-weight: bold;
}
.infobox-container .triangle-l {
border-color: transparent #2083c2 transparent transparent;
border-style:solid;
border-width:13px;
height:0;
width:0;
position: absolute;
left: -12px;
top: 45px;
z-index: 0; /* displayed under infobox */
}
.infobox-container .triangle-r {
border-color: transparent transparent transparent #2083c2;
border-style:solid;
border-width:13px;
height:0;
width:0;
position: absolute;
right: -12px;
top: 45px;
z-index: 0; /* displayed under infobox */
}
.infobox a {
color: #35b0ff;
text-decoration: none;
border-bottom: 1px dotted transparent;
}
.infobox a:hover, .infobox a:focus {
text-decoration: none;
border-bottom: 1px dotted #35b0ff;
}
<div class="infobox-container">
<div class="triangle-l"></div>
<div class="triangle-r"></div>
<h3 class="infobox-ribbon">This is the Header</h3>
<div class="infobox">
<p>This is the content of the infobox.</p>
</div>
</div>
I did a few things here:
I applied * {box-sizing:border-box;}, which does a nicer job at making elements "mold" to the widths that I tell them to (regardless of margins), more details here
I took the h3 ribbon out of the infobox, and changed its position to absolute. My reasoning is that the h3-ribbon needs to conform to the info-box container's width, not the infobox itself. That way, regardless of the width, the ribbon will conform to its parent, and the infobox can occupy its 100% + margins (which should always be even on both sides.)
And like I mentioned before, I changed the fixed-width of the infobox-container to width:100%;max-width:500px;. If you try resizing down, the ribbon stays in place.

Answer 3

I think you can just make a couple of small changes to make all the sizes responsive at least to the content:
The most important changes:
Use 'Calc' to set the width. Support is reasonable well (see caniuse), but you could also solve this differently using negative margins (or probably other ways as well).
.infobox h3 {
width: calc(100% + 20px);
}
The right arrow can simply be solved by setting right to -12px, just as the left one has left: -12px.
.infobox-container .triangle-r {
right: -12px;
}
.infobox-container {
position: relative;
display: inline-block;
margin: 0;
padding: 0;
width: auto;
}
.infobox {
padding: 10px 5px 5px 5px;
margin:10px;
position: relative;
z-index: 90;
-webkit-border-radius: 2px;
-moz-border-radius: 2px;
border-radius: 2px;
-webkit-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
-moz-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
background: #424242;
background-image: -webkit-gradient(linear, left top, left bottom, from(#6a6b6b), to(#424242));
background-image: -moz-linear-gradient(top,#6a6a6a,#424242);
color: #fff;
font-size: 90%;
}
.infobox h3 {
position: relative;
width: calc(100% + 20px);
color: #fff;
padding: 10px 5px;
margin: 0;
left: -15px;
z-index: 100;
-webkit-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
-moz-box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
box-shadow: 0px 0px 3px rgba(0,0,0,0.55);
background: #3198dd;
background-image: -webkit-gradient(linear, left top, left bottom, from(#33acfc), to(#3198dd));
background-image: -moz-linear-gradient(top,#33acfc,#3198dd);
font-size: 160%;
text-align: center;
text-shadow: #2187c8 0 -1px 1px;
font-weight: bold;
}
.infobox-container .triangle-l {
border-color: transparent #2083c2 transparent transparent;
border-style:solid;
border-width:13px;
height:0;
width:0;
position: absolute;
left: -13px;
top: 54px;
z-index: 2; /* displayed under infobox */
}
.infobox-container .triangle-r {
border-color: transparent transparent transparent #2083c2;
border-style:solid;
border-width:13px;
height:0;
width:0;
position: absolute;
right: -12px;
top: 54px;
z-index: 2; /* displayed under infobox */
}
.infobox a {
color: #35b0ff;
text-decoration: none;
border-bottom: 1px dotted transparent;
}
.infobox a:hover, .infobox a:focus {
text-decoration: none;
border-bottom: 1px dotted #35b0ff;
}
<div class="infobox-container">
<div class="triangle-l"></div>
<div class="triangle-r"></div>
<div class="infobox">
<h3><span>This is the Headewefewfewfewfewfewfewfr</span></h3>
<p>This is the content of the infobox.</p>
</div>
</div>