/* Centering Book - HTML Theme for GitHub Pages */

@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+KR:wght@400;700&family=Noto+Sans+KR:wght@400;500;700&family=Noto+Sans+Mono:wght@400;700&display=swap');

/* =========================================
   CSS Custom Properties (Design Tokens)
   ========================================= */
:root {
  --centering-blue:  #4A7C8F;
  --warm-sand:       #F5F1E8;
  --soft-coral:      #E89B8C;
  --forest-green:    #7A9B76;
  --deep-slate:      #2C3E50;
  --gentle-amber:    #F4A460;
  --calm-lavender:   #B4A7D6;
  --light-coral-bg:  #FFF4F3;
  --light-green-bg:  #F2F8F5;
  --light-blue-bg:   #EBF3F6;
  --light-sand-bg:   #FBF8F2;
  --font-serif: 'Noto Serif KR', Georgia, serif;
  --font-sans:  'Noto Sans KR', sans-serif;
  --font-mono:  'Noto Sans Mono', monospace;
  --max-width: 800px;
  --body-size: 17px;
  --line-height: 1.8;
}

/* =========================================
   Base Styles
   ========================================= */
*, *::before, *::after {
  box-sizing: border-box;
}

html {
  font-size: var(--body-size);
}

body {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: var(--line-height);
  color: var(--deep-slate);
  background: #fff;
  margin: 0;
  padding: 0;
}

/* =========================================
   Layout
   ========================================= */
#header,
#content,
#footnotes,
#footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

#content {
  padding-top: 2rem;
  padding-bottom: 4rem;
}

/* Sidebar TOC */
body.toc-left #toc {
  position: fixed;
  left: 0;
  top: 0;
  bottom: 0;
  width: 240px;
  overflow-y: auto;
  padding: 1.5rem 1rem;
  background: var(--light-blue-bg);
  border-right: 1px solid #d0e0e8;
  font-family: var(--font-sans);
  font-size: 0.82rem;
}

body.toc-left #toc ul {
  padding-left: 1rem;
  list-style: none;
}

body.toc-left #toc a {
  color: var(--deep-slate);
  text-decoration: none;
}

body.toc-left #toc a:hover {
  color: var(--centering-blue);
}

body.toc-left #header,
body.toc-left #content,
body.toc-left #footnotes,
body.toc-left #footer {
  margin-left: 260px;
}

@media (max-width: 900px) {
  body.toc-left #toc {
    position: static;
    width: 100%;
    border-right: none;
    border-bottom: 1px solid #d0e0e8;
  }
  body.toc-left #header,
  body.toc-left #content,
  body.toc-left #footnotes,
  body.toc-left #footer {
    margin-left: 0;
  }
}

/* =========================================
   Header
   ========================================= */
#header h1 {
  font-family: var(--font-sans);
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--centering-blue);
  margin: 2rem 0 0.25rem;
  border-bottom: 2px solid var(--centering-blue);
  padding-bottom: 0.5rem;
}

#header .details {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: #777;
  margin-bottom: 1.5rem;
}

/* =========================================
   Headings
   ========================================= */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans);
  color: var(--centering-blue);
  line-height: 1.3;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

h2 { font-size: 1.6rem; border-bottom: 1px solid #d0e0e8; padding-bottom: 0.3rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.05rem; color: var(--deep-slate); }
h5, h6 { font-size: 1rem; color: var(--deep-slate); }

/* =========================================
   Paragraph & Text
   ========================================= */
p {
  margin: 0 0 1rem;
  text-align: justify;
}

strong { color: var(--deep-slate); }
em     { font-style: italic; }

a {
  color: var(--centering-blue);
  text-decoration: underline;
  text-underline-offset: 2px;
}
a:hover { color: var(--soft-coral); }

hr {
  border: none;
  border-top: 1px solid #ccc;
  margin: 1.5rem 0;
}

/* =========================================
   Lists
   ========================================= */
ul, ol {
  padding-left: 1.5rem;
  margin: 0 0 1rem;
}
li { margin-bottom: 0.3rem; }

/* =========================================
   Quote Box  (.quote-box role or blockquote)
   ========================================= */
.quoteblock,
blockquote,
.quote-box {
  background: var(--light-sand-bg);
  border-left: 4px solid var(--gentle-amber);
  padding: 0.8rem 1.2rem;
  margin: 1.2rem 0;
  border-radius: 0 4px 4px 0;
}

.quoteblock .attribution,
.quote-box .attribution {
  font-size: 0.85rem;
  color: #888;
  font-style: italic;
  margin-top: 0.4rem;
}

.quoteblock blockquote {
  border: none;
  background: transparent;
  padding: 0;
  margin: 0;
  font-style: italic;
  color: var(--centering-blue);
  font-size: 1.05rem;
}

/* Chapter quote */
.chapter-quote blockquote {
  text-align: center;
  font-size: 1.15rem;
  border: none;
  background: transparent;
  padding: 1rem 2rem;
  color: var(--centering-blue);
  font-style: italic;
}

/* =========================================
   Admonition Blocks
   ========================================= */
.admonitionblock {
  margin: 1.2rem 0;
  border-radius: 4px;
  overflow: hidden;
}

.admonitionblock table {
  width: 100%;
  border: none;
  background: transparent;
}

.admonitionblock td.icon {
  width: 60px;
  text-align: center;
  padding: 0.75rem 0.5rem;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 700;
  vertical-align: top;
}

.admonitionblock td.content {
  padding: 0.75rem 1rem;
  vertical-align: top;
}

/* TIP = calm lavender (tip-box) */
.admonitionblock.tip {
  background: #F3F1FA;
  border-left: 4px solid var(--calm-lavender);
}
.admonitionblock.tip td.icon {
  color: var(--calm-lavender);
}

/* NOTE = soft coral */
.admonitionblock.note {
  background: var(--light-coral-bg);
  border-left: 4px solid var(--soft-coral);
}
.admonitionblock.note td.icon {
  color: var(--soft-coral);
}

/* IMPORTANT = forest green */
.admonitionblock.important {
  background: var(--light-green-bg);
  border-left: 4px solid var(--forest-green);
}
.admonitionblock.important td.icon {
  color: var(--forest-green);
}

/* WARNING = gentle amber */
.admonitionblock.warning {
  background: #FFF9F0;
  border-left: 4px solid var(--gentle-amber);
}
.admonitionblock.warning td.icon {
  color: var(--gentle-amber);
}

/* =========================================
   Example / Sidebar Blocks
   Concept-box, Practice-box
   ========================================= */
.exampleblock .content,
.concept-box .content,
.practice-box .content {
  background: var(--warm-sand);
  border: 1px solid var(--soft-coral);
  border-radius: 5px;
  padding: 1rem 1.2rem;
  margin: 1.2rem 0;
}

.exampleblock > .title,
.concept-box > .title,
.practice-box > .title {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--centering-blue);
  margin-bottom: 0.5rem;
}

/* Practice-box gets green border */
.practice-box .content {
  background: var(--light-green-bg);
  border-color: var(--forest-green);
}

/* Concept-box gets coral border (default exampleblock) */
.concept-box .content {
  background: var(--light-coral-bg);
  border-color: var(--soft-coral);
}

/* Sidebar block */
.sidebarblock {
  background: var(--light-green-bg);
  border: 1px solid var(--forest-green);
  border-radius: 5px;
  padding: 1rem 1.2rem;
  margin: 1.2rem 0;
}

/* =========================================
   Tables
   ========================================= */
table.tableblock {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.9rem;
}

table.tableblock th {
  background: var(--light-blue-bg);
  color: var(--centering-blue);
  font-family: var(--font-sans);
  font-weight: 700;
  padding: 0.5rem 0.75rem;
  border: 1px solid #ccc;
}

table.tableblock td {
  padding: 0.5rem 0.75rem;
  border: 1px solid #ddd;
  vertical-align: top;
}

table.tableblock tr:nth-child(even) td {
  background: #fafafa;
}

/* =========================================
   Code
   ========================================= */
code, pre {
  font-family: var(--font-mono);
}

code {
  background: var(--light-blue-bg);
  color: var(--centering-blue);
  padding: 0.1em 0.35em;
  border-radius: 3px;
  font-size: 0.875em;
}

pre {
  background: var(--deep-slate);
  color: #d0d8e0;
  padding: 1rem;
  border-radius: 5px;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.5;
}

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

/* =========================================
   Checklist (practice sheets)
   ========================================= */
.checklist li > p:first-child::before {
  content: '☐ ';
}
.checklist li.checked > p:first-child::before {
  content: '☑ ';
}

/* =========================================
   Footer
   ========================================= */
#footer {
  border-top: 1px solid #e0e0e0;
  padding-top: 1rem;
  padding-bottom: 2rem;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: #aaa;
  text-align: center;
}

/* =========================================
   Print / PDF-like styles
   ========================================= */
@media print {
  body.toc-left #toc { display: none; }
  body.toc-left #header,
  body.toc-left #content { margin-left: 0; }
}

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 600px) {
  html { font-size: 15px; }
  #header h1 { font-size: 1.7rem; }
  h2 { font-size: 1.3rem; }
}

/* =========================================
   Book Nav Bar (language switcher + meta site)
   ========================================= */
.book-nav-bar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: saturate(180%) blur(8px);
  -webkit-backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid #E5E7EB;
  padding: 0.55em 1.2em;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-sans, 'Noto Sans KR', sans-serif);
  font-size: 0.85rem;
  letter-spacing: 0.01em;
  margin-bottom: 1.5em;
}
.book-nav-bar a {
  color: var(--centering-blue, #4A7C8F);
  text-decoration: none;
  transition: color 0.15s;
}
.book-nav-bar a:hover { color: var(--deep-slate, #2C3E50); text-decoration: underline; }
.book-nav-bar .nav-home { font-weight: 500; }
.book-nav-bar .nav-lang-switcher { display: inline-flex; align-items: center; gap: 0.4em; }
.book-nav-bar .nav-lang-current { color: #9CA3AF; font-variant: small-caps; letter-spacing: 0.08em; }
.book-nav-bar .nav-lang-sep { color: #D1D5DB; }
.book-nav-bar .nav-lang-other { font-weight: 500; }