Khung 1 :

trèn vào css :

Code:

.codebox {
-moz-border-radius: 5px;
-moz-box-shadow: 0 0 5px #e4e3e3;
-webkit-box-shadow: 0 0 5px #e4e3e3;
background: white;
border: 0;
border-left: 3px solid #999;
border-radius: 5px;
box-shadow: 0 0 5px #e4e3e3;
color: #909090;
font-size: 12px;
font-style: italic;
margin: 10px auto;
max-width: 600px;
padding: 10px 1% 10px 5px;
}

.codebox {
background-color: #FFFFE1;
border: 1px dotted #DDD;
margin: 1em;
}

khung 2:

Code:

.codebox {
margin: 1em;
background: whiteSmoke;
border: 1px solid #C2C0B8;
-webkit-box-shadow: 0 0 60px 10px rgba(0, 0, 0, .1) inset, 0 5px 0 -4px #fff, 0 5px 0 -3px #c2c0b8, 0 11px 0 -8px #fff, 0 11px 0 -7px #c2c0b8, 0 17px 0 -12px #fff, 0 17px 0 -11px #c2c0b8;
-moz-box-shadow: 0 0 60px 10px rgba(0, 0, 0, .1) inset, 0 5px 0 -4px #fff, 0 5px 0 -3px #c2c0b8, 0 11px 0 -8px #fff, 0 11px 0 -7px #c2c0b8, 0 17px 0 -12px #fff, 0 17px 0 -11px #c2c0b8;
box-shadow: 0 0 60px 10px rgba(0, 0, 0, .1) inset, 0 5px 0 -4px #fff, 0 5px 0 -3px #c2c0b8, 0 11px 0 -8px #fff, 0 11px 0 -7px #c2c0b8, 0 17px 0 -12px #fff, 0 17px 0 -11px #c2c0b8;
max-width: 700px;
overflow: hidden;
}


.codebox dd.cont_code {
background: none;
width: 680px;
}

khung 3 :

Code:

.codebox {
  background: #fafafa url(http://cuul.tk/img/gradient.png) repeat-x 0 0px;
border: 1px solid #e3e3e3!important;
    border-radius: 3px 3px 3px 3px;
}

.codebox dt {
background: url(http://i41.servimg.com/u/f41/16/71/63/22/fondoh10.png);
-moz-border-radius-bottomleft:0!important;
-moz-border-radius-bottomright:0!important;
-moz-border-radius-topleft: 3px!important;
-moz-border-radius-topright: 3px!important;
-webkit-border-radius: 3px 3px 0 0!important;
color: #fff;
text-shadow: 0px 2px 3px #000;
padding: 10px;
font-weight: bold;
}

khung 4 :

Code:

.codebox{color: #62761a;  -webkit-box-shadow: 0px 0px 8px 0px rgba(0,0,0,0.2);  -moz-box-shadow: 0px 0px 8px 0px rgba(0,0,0,0.2);  box-shadow: 0px 0px 8px 0px rgba(0,0,0,0.2);  text-shadow: white 1px 1px 0px;  border: 1px solid #b3bca2;  background: url(http://www.9xstudio.biz/users/2012/10/88/45/album/code1110.png);}
.codebox dd{  margin: 0;  border-width: 0px 1px 1px 1px;  border-style: solid;  border-color: white;  border-top: 1px solid white;  background: none;}
.codebox dt{  border-width: 1px 1px 0px 1px;  border-style: solid; border-color: white; border-bottom: 1px solid #b3bca2;  background: url(http://www.9xstudio.biz/users/2012/10/88/45/album/code2110.png);}

khung 5 :

Code:

.codebox {
    -moz-border-bottom-colors: none;
    -moz-border-image: none;
    -moz-border-left-colors: none;
    -moz-border-right-colors: none;
    -moz-border-top-colors: none;
    background: none repeat scroll 0 0 #FFFFFF;
    border-color: -moz-use-text-color -moz-use-text-color -moz-use-text-color #999999;
    border-radius: 5px 5px 5px 5px;
    border-style: none none none solid;
    border-width: 0 0 0 3px;
    box-shadow: 0 0 5px #E4E3E3;
    color: #909090;
    font-size: 12px;
    font-style: italic;
    margin: 10px auto;
    max-width: 600px;
    padding: 10px 1% 10px 5px;
}
98-ltr.css (dòng 1)
.codebox {
    background-color: #FFFFE1;
    border: 1px dotted #DDDDDD;
    margin: 1em;
}
.codebox dd.cont_code {
    background: none repeat scroll 0 0 transparent;
}
98-ltr.css (dòng 1)
.codebox dd.cont_code {
    max-height: 200px;
    overflow: auto;
}
98-ltr.css (dòng 1)
.codebox dd {
    background-color: #FFFFE1;
    margin: 0.5em;
    padding: 0.5em;
}
.codebox dt {
    border-bottom: 1px dotted #DDDDDD;
    color: #6E6E6E;
    font-family: tahoma,arial;
    font-size: 14px;
    font-style: normal;
    font-weight: 700;
    padding: 0.25em;
    text-transform: uppercase;
}
blockquote {
    background-color: #FFFFFF;
    border: 1px solid #DCDCDC;
    border-radius: 5px 5px 5px 5px;
    box-shadow: 0 0 5px #E4E3E3;
    color: #909090;
    font-size: 12px;
    font-style: italic;
    margin: 10px auto;
    max-width: 600px;
    padding: 10px 1%;
}
blockquote div {
    background: url("http://z5.ifrm.com/30015/146/0/p1049280/QuoteL.png") no-repeat scroll left top, url("http://z5.ifrm.com/30015/146/0/p1049281/QuoteR.png") no-repeat scroll right bottom #FFFFFF;
    border-radius: 5px 5px 5px 5px;
    min-height: 25px;
    text-indent: 35px;
}

blockquote code, blockquote div {
    clear: both;
    margin: 0;
    padding: 5px;
}

các bạn thick khung nào thì lấy code ở dưới vả bỏ vào cuối CSS nhé !
nguồn : zone-a7