body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    color: #333;
    transition: background-color 0.3s, color 0.3s;
}

header {
    background-color: #333;
    color: #fff;
    padding: 1rem;
}

nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    display: flex;
}

nav ul li {
    margin-right: 1rem;
}

nav ul li a {
    color: #fff;
    text-decoration: none;
}

main {
    padding: 2rem;
}

section {
    margin-bottom: 2rem;
}

#diary-form {
    display: flex;
    flex-direction: column;
}

#diary-content {
    margin-bottom: 1rem;
    padding: 0.5rem;
}

button {
    padding: 0.5rem 1rem;
    background-color: #333;
    color: #fff;
    border: none;
    cursor: pointer;
}

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

/* 夜间模式样式 */
.dark-mode {
    background-color: #1a1a1a;
    color: #fff;
}

.dark-mode header {
    background-color: #000;
}

.dark-mode button {
    background-color: #000;
}

.dark-mode button:hover {
    background-color: #222;
}