:root {
    --python-blue: #3776ab;
    --python-yellow: #ffd43b;
    --dark-blue: #2a5a87;
    --text-color: #333;
    --bg-light: #f5f5f5;
    --bg-white: #fff;
    --code-bg: #f4f4f4;
    --pre-bg: #2d2d2d;
    --pre-text: #f8f8f2;
    --info-bg: #e3f2fd;
    --shadow: 0 5px 20px rgba(0,0,0,0.1);
}

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

body {
    font-family: 'Segoe UI', Arial, sans-serif;
    background: var(--bg-light);
    line-height: 1.6;
    color: var(--text-color);
}

.header {
    background: linear-gradient(135deg, var(--python-blue), var(--python-yellow));
    color: white;
    padding: 20px;
    text-align: center;
    will-change: transform;
}

.container {
    max-width: 900px;
    margin: 20px auto;
    background: var(--bg-white);
    padding: 40px;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

h1 { color: var(--python-blue); margin-bottom: 20px; }
h2 { color: var(--python-blue); margin-top: 30px; margin-bottom: 15px; }
h3 { color: var(--python-blue); margin-top: 20px; margin-bottom: 10px; }

code {
    background: var(--code-bg);
    padding: 2px 6px;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
}

pre {
    background: var(--pre-bg);
    color: var(--pre-text);
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 15px 0;
    will-change: scroll-position;
}

pre code { background: transparent; color: var(--pre-text); }

.nav {
    display: flex;
    justify-content: space-between;
    margin-top: 40px;
    gap: 10px;
}

.btn {
    background: var(--python-blue);
    color: white;
    padding: 12px 24px;
    border-radius: 6px;
    text-decoration: none;
    transition: background 0.3s;
    display: inline-block;
}

.btn:hover { background: var(--dark-blue); }

.info-box {
    background: var(--info-bg);
    border-left: 4px solid var(--python-blue);
    padding: 15px;
    margin: 20px 0;
    border-radius: 4px;
}

ul, ol { margin-left: 20px; }
li { margin: 8px 0; }
p { margin: 10px 0; }

@media (max-width: 768px) {
    .container { padding: 20px; margin: 10px; }
    .nav { flex-direction: column; }
    .btn { text-align: center; }
    h1 { font-size: 24px; }
    h2 { font-size: 20px; }
}

@media (max-width: 480px) {
    body { font-size: 14px; }
    .container { padding: 15px; }
    pre { padding: 10px; font-size: 12px; }
}