/* ============================================
   컴퓨터 구조 RISC-V판 - 전체 스타일
   ============================================ */

:root {
  --bg: #fafaf7;
  --bg-elev: #ffffff;
  --bg-soft: #f1efe8;
  --text: #1c1c1c;
  --text-muted: #5a5a5a;
  --accent: #c0392b;
  --accent-soft: #fef0ee;
  --border: #e2ddd1;
  --code-bg: #2d2a26;
  --code-text: #f5e9c8;
  --warn-bg: #fff8e1;
  --warn-border: #f0c14b;
  --info-bg: #e8f4fd;
  --info-border: #5fa8d3;
  --success-bg: #e7f6ec;
  --success-border: #4caf50;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 4px 12px rgba(0,0,0,0.04);
  --radius: 10px;
  --max-w: 880px;
}

[data-theme="dark"] {
  --bg: #16181d;
  --bg-elev: #1f2228;
  --bg-soft: #262a31;
  --text: #e8e6e1;
  --text-muted: #a0a0a0;
  --accent: #ff7a6c;
  --accent-soft: #3a1f1c;
  --border: #2f343c;
  --code-bg: #0e1014;
  --code-text: #f5e9c8;
  --warn-bg: #3a3416;
  --warn-border: #b58a30;
  --info-bg: #16303f;
  --info-border: #4a90c2;
  --success-bg: #15331f;
  --success-border: #3a7c4a;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: 'Pretendard', 'Noto Sans KR', -apple-system, BlinkMacSystemFont,
    'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  font-size: 16.5px;
  transition: background .25s ease, color .25s ease;
  overflow-x: hidden;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px dashed transparent;
  transition: border-color .15s ease;
}
a:hover { border-bottom-color: var(--accent); }

/* ============================================
   상단 네비게이션
   ============================================ */
.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-elev);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(8px);
  overflow-x: hidden;
}
.topbar-inner {
  max-width: 1200px;
  width: min(1200px, 100vw);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.brand {
  font-weight: 700;
  font-size: 17px;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  border: none;
}
.brand .badge {
  background: var(--accent);
  color: white;
  font-size: 11px;
  padding: 3px 8px;
  border-radius: 4px;
  font-weight: 600;
  letter-spacing: 0.5px;
}
.nav-links {
  display: flex;
  min-width: 0;
  gap: 6px;
  align-items: center;
  flex-wrap: wrap;
}
.nav-links a {
  color: var(--text-muted);
  font-size: 14px;
  padding: 6px 12px;
  border-radius: 6px;
  border: none;
  white-space: nowrap;
  transition: background .15s ease, color .15s ease;
}
.nav-links a:hover {
  background: var(--bg-soft);
  color: var(--text);
}
.nav-links a.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}
.nav-links a.disabled {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}
.theme-toggle {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
  white-space: nowrap;
  transition: background .15s ease;
}
.theme-toggle:hover { background: var(--border); }

/* ============================================
   메인 레이아웃
   ============================================ */
main {
  max-width: var(--max-w);
  width: min(var(--max-w), 100vw);
  margin: 0 auto;
  padding: 40px 24px 120px;
}

.hero {
  padding: 60px 0 40px;
  text-align: center;
  border-bottom: 1px solid var(--border);
  margin-bottom: 50px;
}
.hero h1 {
  font-size: 42px;
  margin: 0 0 12px;
  letter-spacing: -0.5px;
}
.hero .subtitle {
  color: var(--text-muted);
  font-size: 18px;
  margin: 0;
}
.hero .quote {
  margin-top: 30px;
  font-style: italic;
  color: var(--text-muted);
  font-size: 15px;
}

/* ============================================
   챕터 카드 (인덱스 페이지)
   ============================================ */
.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
  margin-top: 30px;
}
.chapter-card {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  text-decoration: none;
  color: var(--text);
  display: block;
  transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease;
  border-bottom: 1px solid var(--border);
}
.chapter-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: var(--accent);
}
.chapter-card.coming-soon {
  opacity: 0.55;
  cursor: not-allowed;
}
.chapter-card.coming-soon:hover {
  transform: none;
  box-shadow: none;
  border-color: var(--border);
}
.chapter-card .num {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 1px;
  color: var(--accent);
  text-transform: uppercase;
}
.chapter-card h3 {
  margin: 6px 0 10px;
  font-size: 19px;
}
.chapter-card p {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.6;
}
.chapter-card .tag {
  display: inline-block;
  margin-top: 12px;
  font-size: 11px;
  background: var(--bg-soft);
  color: var(--text-muted);
  padding: 3px 8px;
  border-radius: 4px;
}
.chapter-card.available .tag {
  background: var(--accent-soft);
  color: var(--accent);
}

.track-note {
  margin: 0 0 34px;
  padding: 18px 22px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-elev);
  box-shadow: var(--shadow);
}

.track-note h2 {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.chapter-section {
  scroll-margin-top: 90px;
  margin-top: 76px;
}

.chapter-section:first-of-type {
  margin-top: 60px;
}

/* ============================================
   챕터 본문 타이포그래피
   ============================================ */
.chapter-header {
  padding-bottom: 28px;
  border-bottom: 2px solid var(--border);
  margin-bottom: 36px;
}
.chapter-header .ch-num {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 2px;
  color: var(--accent);
  text-transform: uppercase;
}
.chapter-header h1 {
  font-size: 36px;
  margin: 8px 0 6px;
  letter-spacing: -0.5px;
}
.chapter-header .ch-subtitle {
  color: var(--text-muted);
  font-size: 17px;
  margin: 0;
}

h2 {
  font-size: 26px;
  margin: 60px 0 18px;
  padding-top: 16px;
  border-top: 1px dashed var(--border);
  letter-spacing: -0.3px;
}
h2:first-of-type { border-top: none; padding-top: 0; }

h3 {
  font-size: 19px;
  margin: 36px 0 12px;
  color: var(--text);
}

h4 {
  font-size: 16px;
  margin: 24px 0 8px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}

p { margin: 0 0 18px; }

ul, ol { padding-left: 24px; }
li { margin-bottom: 6px; }

strong { color: var(--text); font-weight: 700; }

/* ============================================
   인용/콜아웃 박스
   ============================================ */
blockquote {
  margin: 24px 0;
  padding: 14px 20px;
  border-left: 4px solid var(--accent);
  background: var(--bg-soft);
  font-style: italic;
  color: var(--text-muted);
  border-radius: 0 6px 6px 0;
}
blockquote cite {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  font-style: normal;
  color: var(--text-muted);
}

.callout {
  margin: 24px 0;
  padding: 16px 20px;
  border-radius: var(--radius);
  border-left: 4px solid;
}
.callout-title {
  font-weight: 700;
  margin-bottom: 6px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.callout p:last-child { margin-bottom: 0; }

.callout.principle {
  background: var(--info-bg);
  border-left-color: var(--info-border);
}
.callout.principle .callout-title { color: var(--info-border); }

.callout.hwsw {
  background: var(--success-bg);
  border-left-color: var(--success-border);
}
.callout.hwsw .callout-title { color: var(--success-border); }

.callout.bigpic {
  background: var(--warn-bg);
  border-left-color: var(--warn-border);
}
.callout.bigpic .callout-title { color: #b58a30; }

.callout.check {
  background: var(--accent-soft);
  border-left-color: var(--accent);
}
.callout.check .callout-title { color: var(--accent); }

.callout.witty {
  background: linear-gradient(135deg, var(--accent-soft), var(--bg-soft));
  border-left-color: var(--accent);
  font-size: 15px;
}
.callout.witty .callout-title { color: var(--accent); }

/* ============================================
   코드 블록
   ============================================ */
code {
  font-family: 'JetBrains Mono', 'D2Coding', 'SF Mono', Menlo, monospace;
  font-size: 14px;
  background: var(--bg-soft);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--text);
}

pre {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 18px 20px;
  border-radius: var(--radius);
  overflow-x: auto;
  font-size: 14px;
  line-height: 1.6;
  margin: 18px 0;
}
pre code {
  background: transparent;
  color: inherit;
  padding: 0;
  font-size: inherit;
}
.code-comment { color: #8a9b80; font-style: italic; }
.code-keyword { color: #ffb86c; }
.code-reg     { color: #82aaff; }
.code-num     { color: #f78c6c; }

/* ============================================
   표
   ============================================ */
table {
  border-collapse: collapse;
  width: 100%;
  margin: 20px 0;
  font-size: 14px;
  background: var(--bg-elev);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}
th, td {
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
th {
  background: var(--bg-soft);
  font-weight: 700;
  color: var(--text);
}
tr:last-child td { border-bottom: none; }

.fmt-table {
  font-family: 'JetBrains Mono', monospace;
  text-align: center;
  font-size: 13px;
}
.fmt-table th, .fmt-table td {
  text-align: center;
  border: 1px solid var(--border);
}

/* ============================================
   용어 정의
   ============================================ */
.term {
  background: var(--bg-soft);
  padding: 14px 18px;
  border-radius: 6px;
  margin: 16px 0;
  border-left: 3px solid var(--accent);
}
.term dt {
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 4px;
  font-size: 15px;
}
.term dd {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
}

/* ============================================
   목차 (사이드)
   ============================================ */
.toc {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 0 0 40px;
}
.toc-title {
  font-weight: 700;
  margin-bottom: 10px;
  font-size: 15px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.toc ol {
  margin: 0;
  padding-left: 22px;
}
.toc li { margin-bottom: 4px; }
.toc a {
  color: var(--text);
  border-bottom: none;
  font-size: 14.5px;
}
.toc a:hover { color: var(--accent); }

/* ============================================
   챕터 푸터 네비
   ============================================ */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 80px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  gap: 16px;
}
.chapter-nav a {
  flex: 1;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  padding: 16px 20px;
  border-radius: var(--radius);
  color: var(--text);
  border-bottom: 1px solid var(--border);
  transition: border-color .15s ease, transform .15s ease;
}
.chapter-nav a:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}
.chapter-nav a.disabled {
  opacity: 0.4;
  pointer-events: none;
}
.chapter-nav .label {
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.chapter-nav .title { font-weight: 600; margin-top: 4px; }
.chapter-nav .next { text-align: right; }

/* ============================================
   사이트 푸터
   ============================================ */
.site-footer {
  text-align: center;
  padding: 30px 24px;
  color: var(--text-muted);
  font-size: 13px;
  border-top: 1px solid var(--border);
}

/* ============================================
   반응형
   ============================================ */
@media (max-width: 640px) {
  .hero h1 { font-size: 32px; }
  .chapter-header h1 { font-size: 28px; }
  h2 { font-size: 22px; }
  main {
    width: 100vw;
    max-width: 100vw;
    margin: 0;
    padding: 30px 18px 80px;
  }
  .topbar-inner {
    padding: 12px 18px;
    flex-direction: column;
    align-items: flex-start;
  }
  .brand {
    max-width: 100%;
  }
  .nav-links {
    width: 100%;
    max-width: 100%;
    gap: 2px;
    flex-wrap: nowrap;
    overflow-x: auto;
    padding-bottom: 4px;
    scrollbar-width: none;
  }
  .nav-links a,
  .theme-toggle {
    flex: 0 0 auto;
  }
  .nav-links::-webkit-scrollbar {
    display: none;
  }
  .nav-links a { padding: 5px 8px; font-size: 13px; }
  .hero {
    text-align: left;
    padding: 42px 0 32px;
  }
  .hero .subtitle,
  .hero .quote,
  p,
  li,
  dd {
    overflow-wrap: anywhere;
  }
  table {
    display: block;
    overflow-x: auto;
  }
  .chapter-section { margin-top: 54px; }
}