:root {
  --color-bg: #ffffff;
  --color-text: #1a1a2e;
  --color-heading: #16213e;
  --color-link: #0f4c75;
  --color-link-hover: #3282b8;
  --color-border: #d0d7de;
  --color-table-header: #f0f3f6;
  --color-table-stripe: #f8f9fa;
  --color-code-bg: #f0f3f6;
  --color-nav-bg: #16213e;
  --color-nav-text: #e8e8e8;
  --color-nav-active: #bbe1fa;
  --color-note-bg: #fff8e1;
  --color-note-border: #ffe082;
}

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

body {
  font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  font-size: 15px;
}

nav {
  background: var(--color-nav-bg);
  padding: 0 20px;
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 0;
}

nav .site-title {
  color: #fff;
  font-size: 16px;
  font-weight: bold;
  padding: 12px 16px 12px 0;
  margin-right: 16px;
  border-right: 1px solid rgba(255,255,255,0.2);
  text-decoration: none;
  white-space: nowrap;
}

nav a {
  color: var(--color-nav-text);
  text-decoration: none;
  padding: 12px 16px;
  font-size: 14px;
  transition: color 0.15s;
}

nav a:hover {
  color: #fff;
}

nav a.active {
  color: var(--color-nav-active);
  border-bottom: 2px solid var(--color-nav-active);
}

.page-wrapper {
  display: flex;
  max-width: 1200px;
  margin: 0 auto;
}

.sidebar {
  width: 220px;
  min-width: 220px;
  position: sticky;
  top: 44px;
  height: calc(100vh - 44px);
  overflow-y: auto;
  padding: 20px 12px 32px 16px;
  border-right: 1px solid var(--color-border);
  font-size: 13px;
}

.sidebar ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.sidebar li {
  margin-bottom: 2px;
}

.sidebar a {
  display: block;
  padding: 3px 8px;
  color: var(--color-text);
  text-decoration: none;
  border-radius: 3px;
  line-height: 1.4;
}

.sidebar a:hover {
  background: var(--color-table-stripe);
  color: var(--color-link);
  text-decoration: none;
}

.sidebar .toc-h2 {
  font-weight: bold;
  margin-top: 8px;
}

.sidebar .toc-h3 {
  padding-left: 16px;
  font-size: 12px;
  color: #555;
}

main {
  flex: 1;
  min-width: 0;
  max-width: 900px;
  padding: 32px 24px 64px;
}

h1 {
  font-size: 28px;
  color: var(--color-heading);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-heading);
}

h2 {
  font-size: 22px;
  color: var(--color-heading);
  margin-top: 40px;
  margin-bottom: 12px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--color-border);
}

h3 {
  font-size: 18px;
  color: var(--color-heading);
  margin-top: 28px;
  margin-bottom: 8px;
}

h4 {
  font-size: 15px;
  color: var(--color-heading);
  margin-top: 20px;
  margin-bottom: 6px;
}

p {
  margin-bottom: 12px;
}

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

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

ul, ol {
  margin: 0 0 12px 24px;
}

li {
  margin-bottom: 4px;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0 20px;
  font-size: 14px;
}

th, td {
  border: 1px solid var(--color-border);
  padding: 6px 12px;
  text-align: left;
}

th {
  background: var(--color-table-header);
  font-weight: bold;
  white-space: nowrap;
}

tr:nth-child(even) {
  background: var(--color-table-stripe);
}

code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  background: var(--color-code-bg);
  padding: 1px 5px;
  border-radius: 3px;
  font-size: 13px;
}

pre {
  background: var(--color-code-bg);
  padding: 12px 16px;
  border-radius: 4px;
  overflow-x: auto;
  margin: 8px 0 16px;
  font-size: 13px;
  line-height: 1.5;
}

pre code {
  background: none;
  padding: 0;
}

.note {
  background: var(--color-note-bg);
  border-left: 4px solid var(--color-note-border);
  padding: 10px 16px;
  margin: 12px 0 16px;
  font-size: 14px;
}

.formula {
  background: var(--color-code-bg);
  padding: 8px 16px;
  margin: 8px 0 12px;
  border-radius: 4px;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 14px;
}

.flag-table {
  width: auto;
}

.flag-table td, .flag-table th {
  text-align: center;
  padding: 4px 10px;
}

.inst-section {
  margin-top: 32px;
}

.opcode {
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 13px;
}

.register-diagram {
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 14px;
  line-height: 1.6;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 16px;
  margin: 16px 0;
}

.card {
  border: 1px solid var(--color-border);
  border-radius: 6px;
  padding: 16px;
}

.card h3 {
  margin-top: 0;
  font-size: 16px;
}

.card p {
  font-size: 14px;
  margin-bottom: 0;
}

@media (max-width: 900px) {
  .sidebar {
    display: none;
  }
}

@media (max-width: 640px) {
  nav {
    flex-wrap: wrap;
  }
  nav .site-title {
    width: 100%;
    border-right: none;
    border-bottom: 1px solid rgba(255,255,255,0.2);
    margin-right: 0;
    padding-bottom: 8px;
  }
  main {
    padding: 20px 16px 48px;
  }
  h1 { font-size: 24px; }
  h2 { font-size: 20px; }
  table { font-size: 13px; }
  th, td { padding: 4px 8px; }
}