:root {
    /* Light mode variables */
    --bg-color: #f5f7fa;
    --content-bg: #ffffff;
    --text-color: #333333;
    --heading-color: #2c3e50;
    --link-color: #3498db;
    --link-hover-color: #2980b9;
    --link-bg: #f8f9fa;
    --link-box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    --link-hover-box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
    --border-color: #eee;
    --footer-color: #7f8c8d;
    --content-box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

@media (prefers-color-scheme: dark) {
    :root {
        /* Dark mode variables */
        --bg-color: #1a1a2e;
        --content-bg: #16213e;
        --text-color: #e6e6e6;
        --heading-color: #59a5d8;
        --link-color: #61dafb;
        --link-hover-color: #88e1ff;
        --link-bg: #0f3460;
        --link-box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3);
        --link-hover-box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
        --border-color: #2a4365;
        --footer-color: #a0aec0;
        --content-box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    }
}

* {
    box-sizing: border-box;
    transition:
        background-color 0.3s ease,
        color 0.3s ease,
        border-color 0.3s ease,
        box-shadow 0.3s ease;
}

body {
    font-family:
        -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu,
        Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

h1,
h2,
h3,
h4,
h5,
h6 {
    color: var(--heading-color);
    font-weight: 600;
    line-height: 1.3;
}

h1 {
    font-size: 2rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 10px;
    margin-top: 0;
}

h2 {
    font-size: 1.5rem;
    margin-top: 30px;
}

p {
    margin: 1.2em 0;
}

.header {
    padding: 1rem 0;
}

.header h1 {
    margin: 0;
    border: none;
    font-size: 1.8rem;
}

.header h1 a {
    text-decoration: none;
    color: var(--heading-color);
    background: none;
    box-shadow: none;
    padding: 0;
    margin: 0;
}

.header h1 a:hover {
    text-decoration: underline;
    transform: none;
}

a {
    color: var(--link-color);
    text-decoration: none;
    position: relative;
}

a:hover {
    color: var(--link-hover-color);
}

.links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
    margin: 2rem 0;
}

.links a {
    display: inline-block;
    padding: 15px 30px;
    background-color: var(--link-bg);
    border-radius: 8px;
    box-shadow: var(--link-box-shadow);
    transition: all 0.3s ease;
    font-weight: 500;
}

.links a:hover {
    transform: translateY(-3px);
    box-shadow: var(--link-hover-box-shadow);
}

.content {
    background: var(--content-bg);
    padding: 40px 30px;
    border-radius: 12px;
    box-shadow: var(--content-box-shadow);
    margin-top: 30px;
    text-align: left;
}

main .content h1:first-child {
    text-align: center;
    margin-bottom: 1.5rem;
}

main .content h2 {
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
    margin-top: 2.5rem;
}

main .content ul,
main .content ol {
    padding-left: 1.5rem;
}

main .content li {
    margin-bottom: 0.5rem;
}

.home-page .content {
    text-align: center;
}
.home-page li {
    list-style: none;
}

code {
    background: rgba(0, 0, 0, 0.05);
    padding: 0.2em 0.4em;
    border-radius: 3px;
    font-size: 0.9em;
    font-family:
        SFMono-Regular,
        Consolas,
        Liberation Mono,
        Menlo,
        monospace;
}

@media (prefers-color-scheme: dark) {
    code {
        background: rgba(255, 255, 255, 0.1);
    }
}

blockquote {
    border-left: 4px solid var(--link-color);
    margin-left: 0;
    padding-left: 1rem;
    color: var(--footer-color);
}

/* Footer */
.footer {
    margin-top: 40px;
    text-align: center;
    font-size: 0.9em;
    color: var(--footer-color);
    padding: 1rem 0;
}

/* Print styles */
@media print {
    body {
        font-size: 12pt;
        color: #000;
        background: #fff;
    }
    
    .content {
        box-shadow: none;
        margin: 0;
        padding: 0;
    }
    
    .header, .footer, .links a, .back-to-top {
        display: none;
    }
    
    h1, h2, h3, h4, h5, h6 {
        page-break-after: avoid;
        page-break-inside: avoid;
    }
    
    img, table, pre, blockquote, ul, ol, dl {
        page-break-inside: avoid;
    }
    
    p, h2, h3 {
        orphans: 3;
        widows: 3;
    }
    
    a {
        color: #000;
        text-decoration: underline;
    }
}

/* Back to top button */
.back-to-top {
    position: fixed;
    bottom: 25px;
    right: 25px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background-color: var(--link-color);
    color: white;
    border-radius: 50%;
    opacity: 0;
    visibility: hidden;
    transform: translateY(15px);
    transition: all 0.3s ease;
    z-index: 1000;
    text-decoration: none;
}

.back-to-top.visible {
    opacity: 0.8;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    opacity: 1;
    color: white;
}