创建特殊的CSS形状

Question

我想为我的标题创建一个特殊的CSS形状。必须看起来像这个网站上的第一个讲话泡泡http://nicolasgallagher.com/pure-css-speech-bubbles/demo/，但箭头必须是半圈，而半圈必须始终位于中间。这是用于我的标题，所以即使形状是浏览器长度的100％，该圆也必须留在浏览器的中间，当我调整浏览器窗口的大小时也是如此。

所以我的问题是，这是可能的，如果是这样，如何？

Answer 1

使用border-radius: 50%为半圈，然后将bottom 1/2圆的高度，left: 50%以大部分为中心，然后margin-left变为负1/2的宽度：

.half-circle { 
    background: orange; 
    padding: 1em; 
    position: relative; 
    text-align: center; 
} 
.half-circle::after { 
    background: orange; 
    border-radius: 50%; 
    bottom: -10px; 
    content: ''; 
    display: block; 
    height: 20px; 
    left: 50%; 
    margin-left: -10px; 
    position: absolute; 
    width: 20px; 
}​ 

Here's the fiddle

Answer 2

该代码正确的页面上。一个叫椭圆演讲：

HTML：

<div class="oval-speech">test</div> 

CSS

.oval-speech { 
position:relative; 
width:270px; 
padding:50px 40px; 
margin:1em auto 50px; 
text-align:center; 
color:#fff; 
background:#5a8f00; 
/* css3 */ 
background:-webkit-gradient(linear, 0 0, 0 100%, from(#b8db29), to(#5a8f00)); 
background:-moz-linear-gradient(#b8db29, #5a8f00); 
background:-o-linear-gradient(#b8db29, #5a8f00); 
background:linear-gradient(#b8db29, #5a8f00); 
/* 
NOTES: 
-webkit-border-radius:220px 120px; // produces oval in safari 4 and chrome 4 
-webkit-border-radius:220px/120px; // produces oval in chrome 4 (again!) but not supported in safari 4 
Not correct application of the current spec, therefore, using longhand to avoid future problems with webkit corrects this 

-webkit-border-top-left-radius:220px 120px; 
-webkit-border-top-right-radius:220px 120px; 
-webkit-border-bottom-right-radius:220px 120px; 
-webkit-border-bottom-left-radius:220px 120px; 
-moz-border-radius:220px/120px; 
border-radius:220px/120px;*/ 
} 

.oval-speech p {font-size:1.25em;} 

/* creates part of the curve */ 
.oval-speech:before { 
content:""; 
position:absolute; 
z-index:-1; 
bottom:-30px; 
right:50%; 
height:30px; 
border-right:60px solid #5a8f00; 
background:#5a8f00; /* need this for webkit - bug in handling of border-radius */ 
/* css3 */ 
-webkit-border-bottom-right-radius:80px 50px; 
-moz-border-radius-bottomright:80px 50px; 
border-bottom-right-radius:80px 50px; 
/* using translate to avoid undesired appearance in CSS2.1-capabable but CSS3-incapable browsers */ 
-webkit-transform:translate(0, -2px); 
-moz-transform:translate(0, -2px); 
-ms-transform:translate(0, -2px); 
-o-transform:translate(0, -2px); 
transform:translate(0, -2px); 
} 

/* creates part of the curved pointy bit */ 
.oval-speech:after { 
content:""; 
position:absolute; 
z-index:-1; 
bottom:-30px; 
right:50%; 
width:60px; 
height:30px; 
background:#fff; 
/* css3 */ 
-webkit-border-bottom-right-radius:40px 50px; 
-moz-border-radius-bottomright:40px 50px; 
border-bottom-right-radius:40px 50px; 
/* using translate to avoid undesired appearance in CSS2.1-capabable but CSS3-incapable browsers */ 
-webkit-transform:translate(-30px, -2px); 
-moz-transform:translate(-30px, -2px); 
-ms-transform:translate(-30px, -2px); 
-o-transform:translate(-30px, -2px); 
transform:translate(-30px, -2px); 
}