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

body {
    font-family: Arial, sans-serif;
    background-color: #f5f5f5;
}

header {
    background-color: #333;
    color: white;
    padding: 10px;
    text-align: center;
}

.logo img {
    width: 150px;
}

main {
    padding: 20px;
}

.proveedor {
    border: 1px solid #ddd;
    padding: 20px;
    margin: 10px 0;
    background-color: white;
}

button {
    background-color: #333;
    color: white;
    padding: 10px;
    border: none;
    cursor: pointer;
}

button:hover {
    background-color: #555;
}

form {
    margin: 20px 0;
}

input, select, textarea {
    width: 100%;
    padding: 10px;
    margin-bottom: 10px;
    border: 1px solid #ddd;
}

.calificacion {
    margin-top: 10px;
}