#container{
    width:1200px; background-color: beige;margin: auto;
}
#header{height:200px;border-style: solid;}
#menu{
    background-color: aqua; height:50px;
}
.sp{
    width: 350px;height: 250px; box-sizing: border-box;
    border: solid;float: left;margin: 15px;
    border-radius: 20px;padding: 30px;
}
/*bai 1*/
body{
    font-family: Times New Roman;
    background: #eeeeee;
}

.tieude{
    color: green;
}

.box1{
    width: 600px;
    margin: 20px auto;
    padding: 20px;
    background: #f5f0c8;
    border: 2px solid blue;
    border-radius: 10px;
    text-align: center;
}

.box1 h2{
    color: brown;
}

.box1 p{
    text-align: justify;
    font-size: 16px;
}

.box2{
    width:500px;
    margin:30px auto;
    padding:20px;

    border:2px solid blue;
    border-radius:10px;

    text-align:center;
}

.hinhanh{
    width:100%;
    border-radius:8px;
    margin-bottom:10px;
}

.box2 p{
    text-align:justify;
}
body{
    margin:0;
    font-family: "Times New Roman", Times, serif;
}

/* khung trang */
#container{
    width:100%;
    border:3px solid black;
    min-height:100vh;
    box-sizing: border-box;
}

/* header */
header{
    background:#6f6f6f;
    color:white;
    text-align:center;
    padding:70px 0;
}

header h1{
    margin:0;
    font-size:50px;
}

/* phần giữa */
.main{
    display:flex;
    min-height:400px;
    font-size:35px;
}

/* menu bên trái */
nav{
    width:250px;
    background:#bdbdbd;
    padding:20px;
}

nav a{
    display:block;
    margin-bottom:10px;
    color:purple;
    font-size:35px;
}

/* nội dung bên phải */
section{
    flex:1;
    background:#dcdcdc;
    padding:30px;
}

section h2{
    margin-top:0;
}

/* footer */
footer{
    background:#6f6f6f;
    color:white;
    text-align:center;
    padding:20px;
    font-size:35px;
}body{
    margin:0;
    font-family: "Times New Roman", Times, serif;
}

/* khung trang */
#container{
    width:100%;
    border:3px solid black;
    min-height:100vh;
    box-sizing: border-box;
}

/* header */
header{
    background:#6f6f6f;
    color:white;
    text-align:center;
    padding:70px 0;
}

header h1{
    margin:0;
    font-size:50px;
}

/* phần giữa */
.main{
    display:flex;
    min-height:400px;
    font-size:35px;
}

/* menu bên trái */
nav{
    width:250px;
    background:#bdbdbd;
    padding:20px;
}

nav a{
    display:block;
    margin-bottom:10px;
    color:purple;
    font-size:35px;
}

/* nội dung bên phải */
section{
    flex:1;
    background:#dcdcdc;
    padding:30px;
}

section h2{
    margin-top:0;
}

/* footer */
footer{
    background:#6f6f6f;
    color:white;
    text-align:center;
    padding:20px;
    font-size:35px;
}
/*bai 2*/
body{
    margin:0;
    font-family: "Times New Roman", Times, serif;
}

/* khung trang */
#container{
    width:100%;
    border:3px solid black;
    min-height:100vh;
    box-sizing: border-box;
}

/* header */
header{
    background:#6f6f6f;
    color:white;
    text-align:center;
    padding:70px 0;
}

header h1{
    margin:0;
    font-size:50px;
}

/* phần giữa */
.main{
    display:flex;
    min-height:400px;
    font-size:35px;
}

/* menu bên trái */
nav{
    width:250px;
    background:#bdbdbd;
    padding:20px;
}

nav a{
    display:block;
    margin-bottom:10px;
    color:purple;
    font-size:35px;
}

/* nội dung bên phải */
section{
    flex:1;
    background:#dcdcdc;
    padding:30px;
}

section h2{
    margin-top:0;
}

/* footer */
footer{
    background:#6f6f6f;
    color:white;
    text-align:center;
    padding:20px;
    font-size:35px;
}
/*bai 3*/
body{
    margin:0;
    font-family:Times New Roman;
}

/* Khung chính */
.container{
    width:100%;
    border:2px solid #333;
}

/* Header */
header{
    background:#FCC;
    text-align:center;
    padding:20px;
}

/* Khu vực nội dung */
.content{
    background:#ddd;
    padding:20px;
}

/* 3 cột */
.city{
    float:left;
    width:30%;
    margin:1.5%;
}

/* hình ảnh */
.city img{
    width:100%;
    margin-top:10px;
}

/* Footer */
footer{
    background:#FCC;
    text-align:center;
    padding:15px;
    clear:both;
}
/* #btvn */
    body{
margin:0;
font-family:Arial;
}

.container{
width:1000px;
margin:auto;
border:1px solid black;
}

/* Header */
.header{
background:#ddd;
text-align:center;
padding:30px;
}

/* Banner */
.banner{
background:#a9d6d6;
padding:15px;
}

/* Navigation */
.navigation{
background:#8fbfc0;
padding:15px;
}

/* Main layout */
.main{
overflow:hidden;
}

/* Menu */
.menu{
float:left;
width:25%;
background:#999;
height:200px;
padding:10px;
box-sizing:border-box;
}

/* Content */
.content{
float:left;
width:50%;
background:#bbb;
height:200px;
padding:10px;
box-sizing:border-box;
}

/* Sidebar */
.sidebar{
float:left;
width:25%;
background:#ccc;
height:200px;
padding:10px;
box-sizing:border-box;
}

/* Footer */
.footer{
clear:both;
background:#ddd;
text-align:center;
padding:10px;
}