Thành viên:Đức Anh/Nháp 79

.main-box {
    position: relative;
    margin: 1.2rem auto;
    padding: 1rem 2rem;
    width: 75%;
	font-family: sans-serif;
	font-size:125%;
    box-shadow: 0 2px 5px #c5c5c5;
}
/*Làm màu*/

.main-box.-red {
	background-color: #912a16;
	color:#ffffff;
}
.main-box.-cyan {
	background-color: #2db1b5;	
	color:#ffffff;
}

.main-box.-green {
	background-color: #107d28;
	color:#ffffff;
}

.main-box.-yellow {
	background-color:#e6db8c;
	color:#000000;
}

/*Hết làm màu*/
.main-box::before {
    content: "";
    z-index: -1;
    position: absolute;
    top: 0;
    right: 0;
    width: 100%;
    height: 100%;
    background-image: url(https://upload.wikimedia.org/wikipedia/commons/3/3b/SteacieLibrary.jpg);
    background-size: cover;
    background-repeat: no-repeat;
}

.main-box *::selection {
    background: rgba(236,236,236,0.35);
}

.main-box a {
    color: #ffff76;
}

.main-box a:active,
.main-box a:focus {
    background-color: rgba(255,207,98,0.5);
    color: #fff;
}