*, *::before, *::after { box-sizing: border-box; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: 14px; line-height: 1.65; color: #1a1a2e; background: #f6f7fb;
  max-width: 820px; margin: 48px auto; padding: 0 28px;
}

header { margin-bottom: 18px; }
h1 { font-size: 1.75em; font-weight: 700; margin: 6px 0 4px; letter-spacing: -0.02em; }
.subtitle { color: #6b7280; font-size: 0.95em; margin: 0; }

.back { font-size: 0.9em; font-weight: 600; text-decoration: none; color: #4f6ef7; }

nav.tabs { display: flex; flex-wrap: wrap; gap: 4px; margin: 14px 0 24px; border-bottom: 1px solid #e5e7eb; }
nav.tabs a {
  padding: 8px 16px; font-size: 0.9em; font-weight: 600; color: #6b7280;
  text-decoration: none; border-bottom: 2px solid transparent; margin-bottom: -1px;
}
nav.tabs a:hover { color: #4f6ef7; }
nav.tabs a.active { color: #4f6ef7; border-bottom-color: #4f6ef7; }

h2 { font-size: 1.25em; color: #1a1a2e; margin: 34px 0 10px; padding-bottom: 6px; border-bottom: 2px solid #eef0f6; }
h3 { font-size: 1.05em; margin: 22px 0 8px; }
p { margin: 12px 0; color: #27314a; }
a { color: #4f6ef7; }

code {
  font-family: "SF Mono", ui-monospace, Menlo, Consolas, monospace;
  font-size: 0.88em; background: #eef2ff; padding: 1px 5px; border-radius: 4px; color: #4338ca;
}
.try { font-weight: 700; color: #0f766e; }

pre.term {
  background: #1e2233; color: #e7e9f0; border-radius: 8px; padding: 14px 16px;
  overflow-x: auto; font-size: 0.86em; line-height: 1.5; white-space: pre;
  font-family: "SF Mono", ui-monospace, Menlo, Consolas, monospace; margin: 14px 0;
}

.note {
  background: #fff; border: 1px solid #e5e7eb; border-left: 4px solid #4f6ef7;
  border-radius: 6px; padding: 12px 16px; margin: 16px 0; color: #4b5563; font-size: 0.92em;
}
.warning {
  background: #fff7f7; border: 1px solid #f3d0d0; border-left: 4px solid #dc2626;
  border-radius: 6px; padding: 12px 16px; margin: 16px 0; color: #7f1d1d; font-size: 0.92em;
}
.todo {
  background: #fffbeb; border: 1px solid #fde68a; border-left: 4px solid #d97706;
  border-radius: 6px; padding: 12px 16px; margin: 16px 0; color: #78350f; font-size: 0.92em;
}

.tree {
  background: #fff; border: 1px solid #e5e7eb; border-radius: 8px; padding: 14px 18px;
  font-family: "SF Mono", ui-monospace, Menlo, Consolas, monospace; font-size: 0.85em;
  color: #374151; white-space: pre; overflow-x: auto; margin: 14px 0;
}

figure { margin: 20px 0; text-align: center; }
figure img {
  display: inline-block; width: auto; height: auto;
  max-width: min(100%, 560px); max-height: 440px;
  border: 1px solid #e5e7eb; border-radius: 8px; background: #fff;
}
figcaption { color: #6b7280; font-size: 0.85em; margin-top: 6px; }

table { border-collapse: collapse; width: 100%; margin: 14px 0; font-size: 0.9em; }
th, td { border: 1px solid #e5e7eb; padding: 7px 10px; text-align: left; vertical-align: top; }
th { background: #eef2ff; color: #3730a3; }

ol, ul { margin: 12px 0; padding-left: 26px; }
ol li, ul li { margin: 6px 0; }

.next {
  display: inline-block; margin: 30px 0 10px; padding: 10px 18px; background: #4f6ef7;
  color: #fff; border-radius: 6px; text-decoration: none; font-weight: 600; font-size: 0.9em;
}
.next:hover { background: #3b56d4; }

.card-list { list-style: none; padding: 0; margin: 18px 0; }
.card-list li {
  background: #fff; border: 1px solid #e5e7eb; border-radius: 8px;
  padding: 12px 16px; margin: 10px 0;
}
.card-list a { font-weight: 700; font-size: 1.02em; text-decoration: none; }
.card-list .desc { color: #6b7280; font-size: 0.9em; margin-top: 3px; }

footer { margin-top: 40px; padding-top: 14px; border-top: 1px solid #e5e7eb; color: #9ca3af; font-size: 0.82em; }

@media (max-width: 680px) {
  body { margin: 24px auto; padding: 0 16px; }
}