* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; background: #f4f6f9; color: #1a1a2e; line-height: 1.7; }
.chapter { max-width: 860px; margin: 40px auto; padding: 40px 48px; background: #fff; border-radius: 16px; box-shadow: 0 2px 12px rgba(0,0,0,0.06); }
h1 { font-size: 2rem; font-weight: 700; color: #0d47a1; margin: 24px 0 12px; }
h2 { font-size: 1.4rem; font-weight: 600; color: #1565c0; margin: 28px 0 10px; padding-bottom: 4px; border-bottom: 2px solid #e3f2fd; }
h3 { font-size: 1.1rem; font-weight: 600; color: #1e3a5f; margin: 20px 0 8px; }
p { margin: 10px 0; color: #2c3e50; }
ul, ol { margin: 10px 0 10px 24px; }
li { margin: 6px 0; color: #2c3e50; }
a { color: #1565c0; text-decoration: none; }
a:hover { text-decoration: underline; }
pre { background: #1a1a2e; color: #e8e8e8; padding: 16px 20px; border-radius: 10px; overflow-x: auto; font-size: 13px; line-height: 1.5; margin: 14px 0; }
code { font-family: 'JetBrains Mono', 'Fira Code', monospace; }
p code, li code { background: #eef2f7; padding: 2px 6px; border-radius: 4px; font-size: 0.9em; color: #0d47a1; }
pre code { background: transparent; padding: 0; color: inherit; }
img { max-width: 100%; height: auto; border-radius: 8px; margin: 16px 0; border: 1px solid #e0e0e0; }
table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 14px; }
th { background: #e3f2fd; color: #0d47a1; font-weight: 600; text-align: left; padding: 10px 12px; border: 1px solid #bbdefb; }
td { padding: 8px 12px; border: 1px solid #e0e0e0; }
tr:nth-child(even) { background: #f8faff; }
.note { background: #e3f2fd; border-left: 4px solid #1565c0; padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 16px 0; }
.tip { background: #e8f5e9; border-left: 4px solid #2e7d32; padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 16px 0; }
.warn { background: #fff3e0; border-left: 4px solid #e65100; padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 16px 0; }
.tag { display: inline-block; background: #1565c0; color: #fff; font-size: 12px; font-weight: 600; padding: 3px 10px; border-radius: 12px; text-transform: uppercase; letter-spacing: 0.5px; }
.exercise { background: #f3e5f5; border: 1px solid #ce93d8; border-radius: 10px; padding: 20px; margin: 20px 0; }
.exercise h3 { color: #6a1b9a; margin-top: 0; }
.exam-tip { background: #fff8e1; border: 1px solid #ffd54f; border-radius: 10px; padding: 16px 20px; margin: 16px 0; }
.exam-tip h3 { color: #f57f17; margin-top: 0; font-size: 1rem; }
nav { display: flex; justify-content: space-between; align-items: center; margin-top: 40px; padding-top: 20px; border-top: 1px solid #e0e0e0; font-size: 14px; }
.toc { list-style: none; margin: 20px 0; padding: 0; }
.toc li { border-bottom: 1px solid #f0f0f0; }
.toc a { display: flex; justify-content: space-between; align-items: center; padding: 14px 16px; border-radius: 8px; transition: background 0.2s; }
.toc a:hover { background: #e3f2fd; text-decoration: none; }
.toc small { color: #666; font-size: 12px; }
@media (max-width: 768px) { .chapter { padding: 20px 16px; margin: 16px; } h1 { font-size: 1.5rem; } h2 { font-size: 1.2rem; } }