* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    } 
body {
    font-family: Arial;
    display: flex;
    min-height: 100vh;/*1vh=1/100 chieu cao view*/
}
.leftbar {
    width: 250px;
    background-color: #2c3e50;
    color: white;
    padding: 1rem;
} 
.leftbar h2{
    margin-bottom: 2rem;
}
.leftbar a{
    display: block;
    color: white;
    text-decoration: none;
    margin-bottom: 1rem;
}
.leftbar a:hover{
    text-decoration: underline;
}
.main{
    flex-grow: 1;
    padding: 2rem;
}   
    .card{
        display: grid;
        grid-template-columns: repeat(auto-fit,minmax(200px,1fr));
        gap: 1rem;
    }
    .card{
        background: 1.5rem;
        padding: 1.5rem;
        border-radius: 8px;
        box-shadow: 0 0 10px rgba(0,0,0,0.1);
    }
    .card h3{
        margin-bottom: 0.5rem;
    }
    table{
        width: 100%;
        border-collapse: collapse;
        margin-top: 2rem;
    }
    table th,table td {
        padding: 0.75rem;
        text-align: left;
        border-bottom: 1px solid #ccc;
    }
    table th{
        background-color: #ecf0f1;
    }