body {
    font-family: 'Segoe UI', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    max-width: 900px;
    margin: auto;
    padding: 20px;
    line-height: 1.6;
    background-color: #f9f9f9;
    color: #333;
}

#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 8px 12px;
    font-style: 18px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    background-color: #1a73e8;
    color: white;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transition: background-color 0.3s;
}

#theme-toggle:hover {
    background-color: #155ab6;
}

body.dark-theme {
    background-color: #121212;
    color: #e0e0e0;
}

body.dark-theme header {
    background-color: #1e1e1e;
    border-bottom: 2px solid #333;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.05)
}

body.dark-theme a {
    color: #e0e0e0;
}

body.dark-theme section {
    background-color: #1e1e1e;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
}

body, section, h1, h2, p, a {
    transition: background-color 0.3s, color 0.3s;
}

#theme-toggle {
    margin-left: auto;
}

header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: #fff;
    padding: 10px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid #e0e0e0;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

nav a {
    margin: 0 10px;
    color: #1a73e8;
    text-decoration: none;
    font-weight: bold;
}

nav a:hover {
    text-decoration: underline;
}

section {
    margin-bottom: 40px;
    padding: 20px;
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
}

h1 {
    color: #1a73e8;
    font-size: 2.5em;
}

h2 {
    color: #555;
    margin-bottom: 15px;
}

h1, h2 {
    margin-bottom: 15px;
    font-weight: bold;
}

ul {
    list-style-type: square;
    padding-left: 20px;
}

a {
    color: #1a73e8;
    text-decoration: underline;
}

footer {
    text-align: center;
    margin-top: 50px;
    padding-top: 20px;
    border-top: 2px solid #e0e0e0;
    font-size: 0.9em;
    color: #666;
}