body {
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh; /* full viewport height */
    font-family: 'Ubuntu', sans-serif;
}

header {
    background-color: #1F4550;
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: white;
}

main {
    flex: 1; /* push footer down */
}

footer {
    padding: 20px;
}

.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 20px;
    padding: 20px;
    max-width: 1200px;
    margin: auto;
}

.device-card {
    background: white;
    text-align: center;
    text-decoration: none;
    padding: 20px;
    color: #333;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    transition: transform 0.2s, box-shadow 0.2s;
}

.device-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.device-card i {
    color: #2980b9;
}

.device-icon {
    width: 64px;
    height: 64px;
}