body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 20px;
    background-color: #f4f4f4;
    color: #333;
}

header, footer {
    text-align: center;
    margin-bottom: 20px;
}

h1 {
    color: #2c3e50;
}

h2 {
    color: #34495e;
    border-bottom: 2px solid #3498db;
    padding-bottom: 10px;
    margin-top: 40px;
}

h3 {
    color: #3498db;
}

main {
    max-width: 800px;
    margin: 0 auto;
    background: #fff;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.week {
    margin-bottom: 30px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 15px;
}

th, td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

th {
    background-color: #ecf0f1;
}

tr:hover {
    background-color: #f9f9f9;
}

td:last-child {
    text-align: center;
}

input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.extra-tips {
    margin-top: 40px;
    padding: 20px;
    background: #ecf0f1;
    border-radius: 5px;
}

.extra-tips h3 {
    margin-top: 0;
    color: #34495e;
}

.extra-tips ul {
    padding-left: 20px;
}

.extra-tips li {
    margin-bottom: 10px;
}

tr.completed {
    background-color: #e8f5e9; /* Light green background */
    text-decoration: line-through;
    color: #757575;
}