* { box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", sans-serif; margin: 0; padding: 0; background: #ffffff; color: #111827; }
main { max-width: 860px; margin: 0 auto; padding: 32px 24px 64px; }
h1 { font-size: 26px; color: #111827; margin: 0 0 8px; line-height: 1.35; }
h2 { font-size: 20px; color: #dc2626; margin: 40px 0 12px; padding-bottom: 6px; border-bottom: 1px solid #e5e7eb; }
h3 { font-size: 16px; color: #111827; margin: 24px 0 8px; }
p { line-height: 1.85; color: #374151; margin: 0 0 14px; }
.lead { font-size: 15px; color: #6b7280; margin-bottom: 20px; line-height: 1.8; }
.meta { font-size: 12px; color: #9ca3af; margin-bottom: 28px; }
ul, ol { line-height: 1.85; color: #374151; padding-left: 1.4em; }
li { margin: 4px 0; }
code { background: #f3f4f6; padding: 2px 6px; border-radius: 4px; font-size: 13px; color: #b91c1c; }
pre { background: #f9fafb; border: 1px solid #e5e7eb; border-radius: 8px; padding: 12px 14px; overflow-x: auto; font-size: 13px; line-height: 1.6; }
pre code { background: transparent; padding: 0; color: #111827; }
table { border-collapse: collapse; width: 100%; margin: 12px 0 18px; font-size: 13px; }
th, td { border: 1px solid #e5e7eb; padding: 6px 10px; text-align: left; vertical-align: top; }
th { background: #f9fafb; color: #374151; font-weight: 600; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
.tablewrap { overflow-x: auto; }
.note { background: #fffbeb; border: 1px solid #fde68a; border-radius: 8px; padding: 12px 16px; margin: 16px 0; }
.note .t { font-weight: 600; color: #92400e; font-size: 13px; margin-bottom: 4px; }
.note p { margin: 0 0 6px; font-size: 13.5px; }
.term { background: #eff6ff; border: 1px solid #bfdbfe; border-radius: 8px; padding: 12px 16px; margin: 16px 0; }
.term .t { font-weight: 600; color: #1d4ed8; font-size: 13px; margin-bottom: 4px; }
.term p { margin: 0 0 6px; font-size: 13.5px; }
.result { background: #f0fdf4; border: 1px solid #bbf7d0; border-radius: 8px; padding: 12px 16px; margin: 16px 0; }
.result .t { font-weight: 600; color: #166534; font-size: 13px; margin-bottom: 4px; }
.result p { margin: 0 0 6px; }
blockquote { border-left: 3px solid #e5e7eb; margin: 12px 0; padding: 4px 16px; color: #4b5563; }
.abstract { background: #fff7f7; border-left: 4px solid #dc2626; border-radius: 0 8px 8px 0; padding: 12px 16px; margin: 0 0 20px; }
.abstract .t { font-weight: 600; color: #dc2626; font-size: 13px; margin-bottom: 4px; }
.abstract ul { margin: 0; font-size: 14px; }
.toc ol ol { margin: 2px 0 4px; font-size: 13px; }
.toc a { text-decoration: none; }
.toc a:hover { text-decoration: underline; }
.toc { background: #f9fafb; border: 1px solid #e5e7eb; border-radius: 8px; padding: 12px 18px; margin: 0 0 28px; font-size: 13.5px; }
.toc ol { margin: 6px 0 0; }
.series { display: grid; grid-template-columns: 1fr; gap: 14px; margin: 20px 0; }
.card { border: 1px solid #e5e7eb; border-radius: 10px; padding: 16px 18px; }
.card h3 { margin: 0 0 6px; font-size: 16px; }
.card p { margin: 0; font-size: 13.5px; }
.card .lvl { display: inline-block; font-size: 11px; padding: 2px 8px; border-radius: 10px; margin-bottom: 8px; }
.lvl.easy { background: #dcfce7; color: #166534; }
.lvl.tech { background: #ede9fe; color: #5b21b6; }
.navlinks { margin-top: 48px; padding-top: 16px; border-top: 1px solid #e5e7eb; font-size: 13.5px; display: flex; gap: 16px; flex-wrap: wrap; }
a { color: #1d4ed8; }
.MathJax { max-width: 100%; overflow-x: auto; }
@media (max-width: 640px) { main { padding: 20px 14px 48px; } h1 { font-size: 22px; } }

.tabs { display: flex; gap: 6px; flex-wrap: wrap; margin: 12px 0 0; }
.tabs .tab { border: 1px solid #e5e7eb; background: #f9fafb; color: #374151; border-radius: 8px 8px 0 0; padding: 6px 12px; font-size: 13px; cursor: pointer; }
.tabs .tab.active { background: #dc2626; color: #fff; border-color: #dc2626; }
.tabpane { border: 1px solid #e5e7eb; border-radius: 0 8px 8px 8px; padding: 10px 12px 4px; margin-bottom: 12px; }
.tabpane table { margin-top: 6px; }
.tabdesc { font-size: 13px; color: #6b7280; margin: 0 0 6px; }
td strong em { font-style: italic; }