*{
            margin: 0;
            padding: 0;
            box-sizing: border-box;
}

body {
        font-family: Arial;
        display: flex;
        min-height: 100vh;/*1vh = 1/100 chiều cao view*/
        background:#f4f4f4;
        }
.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;
}
.cards {
        display: grid;
        grid-template-columns: repeat (auto-fit, minmax (200px, 1fr));
        gap: 1rem;
}
.card {
        background: white;
        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;
}
table th, table td {
        padding: 0.75rem;
        text-align: left;
        border-bottom: 1px solid #ccc;
}
table th {
        background-color: #ecf0f1;
}