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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, system-ui, sans-serif;
    line-height: 1.6;
    color: #374151;
    background: #fff;
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 20px;
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 60px;
    padding-bottom: 20px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: #111827;
    text-decoration: none;
}

nav {
    display: flex;
    gap: 30px;
}

nav a {
    color: #6b7280;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

nav a:hover {
    color: #111827;
}

.dark-mode {
    background-color: #1a1a1a;
    color: #e5e5e5;
}

.dark-mode a {
    color: #e5e5e5;
}

.dark-mode .logo {
    color: #ffffff;
}

.dark-mode nav a:hover {
    color: #ffffff;
}

@media (max-width: 640px) {
    body {
        padding: 20px;
    }

    header {
        flex-direction: column;
        align-items: flex-start;
        gap: 20px;
    }

    nav {
        gap: 20px;
    }
}