body {
    font-family: sans-serif;
    background: #f9f9f9;
    padding: 2rem;
}

/* 中央寄せ用 main */
main {
    background: #fff;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 0 5px rgba(0,0,0,0.1);
    max-width: 800px;  /* 中央に幅を制限 */
    margin: 0 auto;    /* 中央寄せ */
}

header, footer {
    background: #e9e9e9;
    padding: 1rem;
    text-align: center;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
    background: white;
}

th, td {
    border: 1px solid #ccc;
    padding: 0.5rem;
    text-align: center;
}

th {
    background: #eee;
}

nav a {
    display: inline-block;
    padding: 10px 20px;
    margin: 5px;
    text-decoration: none;
    background-color: #3498db;
    color: white;
    border-radius: 5px;
    transition: background-color 0.3s ease;
    font-weight: bold;
}

nav a:hover {
    background-color: #2980b9;
}

.amount {
    color: #ff0000;
    margin: 20px 0;
    text-align: left;
}

h2, h3 {
    margin: 20px 0;
    text-align: left;
}

/* モバイル用 */
@media (max-width: 768px) {
    .log-group {
        overflow-x: auto;
        width: 100%;
    }

    .log-group table {
        display: table;
        margin: 0 auto; /* 中央寄せ */
        white-space: nowrap;
    }

    th, td {
        font-size: 0.8rem;
        padding: 0.4rem;
    }

    .amount,
    h2,
    h3 {
        text-align: left;
        margin-left: 0;
        margin-right: 0;
    }
}