body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
}

header {
    background-color: #222;
    color: white;
    padding: 1em;
    text-align: center;
}

nav a {
    margin: 0 1em;
    color: white;
    text-decoration: none;
}

main {
    padding: 2em;
}

.obra-table {
    width: 100%;
    border-collapse: collapse;
}

.obra-table th, .obra-table td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: center;
}

.thumbnail {
    width: 100px;
    cursor: pointer;
}

.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    padding-top: 60px;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.8);
}

.modal-content {
    display: block;
    margin: auto;
    max-width: 90%;
}

.close {
    position: absolute;
    top: 30px;
    right: 35px;
    color: white;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
}