/* Reset CSS cơ bản */
* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; }

:root {
    --red-tet: #c0392b;
    --yellow-tet: #f1c40f;
    --green-tet: #27ae60;
    --light-gray: #f4f4f4;
}

body { line-height: 1.6; background-color: var(--light-gray); color: #333333; }

/* Header & Navigation */
header {
    background-color: var(--red-tet);
    color: white;
    padding: 1rem 0;
    text-align: center;
    border-bottom: 5px solid var(--yellow-tet);
}

nav {
    background: #a93226;
    position: sticky;
    top: 0;
    z-index: 1000;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
}

nav ul li a {
    color: white;
    text-decoration: none;
    padding: 15px 20px;
    display: block;
    font-weight: bold;
    transition: 0.3s;
}

nav ul li a:hover { background: var(--yellow-tet); color: var(--red-tet); }

/* Banner */
.banner {
    height: 400px;
    background: linear-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.5)), url('../img/banner.jpg') no-repeat center center/cover;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-align: center;
}

/* Main Content */
main { max-width: 1100px; margin: 20px auto; padding: 20px; background: white; border-radius: 8px; }

h2 { color: var(--red-tet); border-left: 5px solid var(--green-tet); padding-left: 10px; margin: 20px 0; }

.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.card {
    border: 1px solid #ddd;
    padding: 15px;
    border-radius: 10px;
    text-align: center;
    transition: transform 0.3s;
}

.card:hover { transform: translateY(-5px); border-color: var(--red-tet); }

.card img { width: 100%; height: 200px; object-fit: cover; border-radius: 5px; }

/* Footer */
footer {
    background: #333;
    color: white;
    text-align: center;
    padding: 20px 0;
    margin-top: 40px;
}