/* =========================================================
   Quiz Java GUI — Markdown Preview
   Theme: inspired by markdown-preview-enhanced (GitHub-light)
   ========================================================= */

:root {
  --bg: #ffffff;
  --bg-soft: #f6f8fa;
  --bg-sidebar: #fbfbfa;
  --bg-code: #f6f8fa;
  --bg-inline-code: rgba(175, 184, 193, 0.2);
  --fg: #1f2328;
  --fg-muted: #656d76;
  --fg-dim: #8c959f;
  --border: #d0d7de;
  --border-soft: #e7eaee;
  --accent: #0969da;
  --accent-soft: #ddf4ff;
  --accent-fg: #0550ae;
  --green: #1a7f37;
  --orange: #bc4c00;
  --red: #cf222e;
  --yellow: #bf8700;
  --quote-border: #d0d7de;
  --table-stripe: #f6f8fa;
  --shadow-sm: 0 1px 0 rgba(31, 35, 40, 0.04);
  --shadow-md: 0 8px 24px rgba(140, 149, 159, 0.2);
  --selection: rgba(9, 105, 218, 0.2);

  --font-body: "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-display: "Newsreader", "IBM Plex Sans", serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
}

[data-theme="dark"] {
  --bg: #0d1117;
  --bg-soft: #161b22;
  --bg-sidebar: #0a0d12;
  --bg-code: #161b22;
  --bg-inline-code: rgba(110, 118, 129, 0.4);
  --fg: #e6edf3;
  --fg-muted: #8d96a0;
  --fg-dim: #6e7681;
  --border: #30363d;
  --border-soft: #21262d;
  --accent: #2f81f7;
  --accent-soft: #1f3a5f;
  --accent-fg: #79c0ff;
  --green: #3fb950;
  --orange: #db6d28;
  --red: #f85149;
  --yellow: #d29922;
  --quote-border: #30363d;
  --table-stripe: #161b22;
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.5);
  --selection: rgba(47, 129, 247, 0.4);
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--fg);
  display: grid;
  grid-template-columns: 280px 1fr;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background 0.2s ease, color 0.2s ease;
}

::selection { background: var(--selection); }

/* =========================================================
   Sidebar
   ========================================================= */
.sidebar {
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-soft);
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sidebar-header {
  padding: 22px 20px 16px;
  border-bottom: 1px solid var(--border-soft);
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-mark {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent) 0%, #1f6feb 100%);
  color: #fff;
  display: grid;
  place-items: center;
  flex-shrink: 0;
  box-shadow: 0 2px 6px rgba(9, 105, 218, 0.25);
}

.logo-mark svg { width: 18px; height: 18px; }

.logo h1 {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 600;
  margin: 0;
  letter-spacing: -0.01em;
  line-height: 1.1;
}

.logo .subtitle {
  margin: 2px 0 0;
  font-size: 11px;
  color: var(--fg-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-weight: 500;
}

.file-list {
  flex: 1;
  overflow-y: auto;
  padding: 12px 10px;
  display: flex;
  flex-direction: column;
  gap: 1px;
}

.file-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 13.5px;
  color: var(--fg);
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.12s ease;
  font-family: var(--font-body);
  background: transparent;
  text-align: left;
  width: 100%;
  min-width: 0;
}

.file-item:hover {
  background: var(--bg-soft);
}

.file-item.active {
  background: var(--accent-soft);
  border-color: rgba(9, 105, 218, 0.15);
  color: var(--accent-fg);
  font-weight: 500;
}

.file-item .file-icon {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  color: var(--fg-dim);
}

.file-item.active .file-icon { color: var(--accent); }

.file-item .file-name {
  font-family: var(--font-mono);
  font-size: 12.5px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.file-item .file-num {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--fg-dim);
  margin-left: auto;
  letter-spacing: 0.05em;
}

.sidebar-footer {
  padding: 14px 18px;
  border-top: 1px solid var(--border-soft);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.upload-box {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-soft);
}

.upload-actions {
  display: flex;
  gap: 6px;
}

.upload-btn,
.delete-file-btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  padding: 7px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 12px;
  font-weight: 600;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}

.upload-btn:hover,
.delete-file-btn:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--bg-soft);
}

.delete-file-btn {
  color: var(--red);
}

.delete-file-btn:hover:not(:disabled) {
  border-color: rgba(207, 34, 46, 0.3);
  color: var(--red);
}

.delete-file-btn:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.upload-input {
  display: none;
}

.upload-status {
  margin: 0;
  color: var(--fg-muted);
  font-size: 11px;
  line-height: 1.35;
}

.upload-status.error {
  color: var(--red);
}

.upload-status.success {
  color: var(--green);
}

.meta-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 11.5px;
  color: var(--fg-muted);
}

.meta-key {
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 500;
}

.meta-val {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--fg);
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
  color: var(--fg);
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: border-color 0.15s, background 0.15s;
}

.theme-toggle:hover { border-color: var(--accent); }

.theme-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 2px rgba(9, 105, 218, 0.18);
}

[data-theme="dark"] .theme-dot { background: var(--yellow); box-shadow: 0 0 0 2px rgba(210, 153, 34, 0.25); }

/* =========================================================
   Main content
   ========================================================= */
.main {
  display: flex;
  flex-direction: column;
  min-width: 0;
  background: var(--bg);
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 32px;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--border-soft);
}

[data-theme="dark"] .topbar { background: rgba(13, 17, 23, 0.85); }

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12.5px;
}

.bc-root { color: var(--fg-muted); }
.bc-sep { color: var(--fg-dim); }
.bc-file { color: var(--fg); font-weight: 500; }

.icon-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 12.5px;
  font-weight: 500;
  transition: all 0.12s;
}

.icon-btn:hover { border-color: var(--accent); color: var(--accent); }

.content-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 240px;
  gap: 48px;
  padding: 48px 48px 80px;
  max-width: 1200px;
  margin: 0 auto;
  width: 100%;
}

.content-wrap.no-toc { grid-template-columns: minmax(0, 1fr); }

.markdown-body {
  min-width: 0;
  max-width: 760px;
}

.loading {
  color: var(--fg-muted);
  font-style: italic;
  padding: 40px 0;
}

/* =========================================================
   TOC sidebar
   ========================================================= */
.toc {
  position: sticky;
  top: 80px;
  align-self: start;
  font-size: 12.5px;
  border-left: 1px solid var(--border-soft);
  padding: 4px 0 4px 18px;
  max-height: calc(100vh - 120px);
  overflow-y: auto;
}

.toc-title {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin: 0 0 12px;
  font-weight: 600;
}

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

.toc-list li { margin: 4px 0; }
.toc-list .toc-h3 { padding-left: 14px; }

.toc-list a {
  color: var(--fg-muted);
  text-decoration: none;
  display: block;
  padding: 3px 8px;
  border-left: 2px solid transparent;
  margin-left: -10px;
  transition: color 0.12s, border-color 0.12s;
  line-height: 1.4;
}

.toc-list a:hover { color: var(--fg); }
.toc-list a.active { color: var(--accent); border-left-color: var(--accent); font-weight: 500; }

.toc.hidden { display: none; }
.content-wrap:has(.toc.hidden) { grid-template-columns: minmax(0, 1fr); }

/* =========================================================
   Markdown body — MPE github-light flavored
   ========================================================= */
.markdown-body { line-height: 1.65; font-size: 16px; }

.markdown-body > *:first-child { margin-top: 0; }
.markdown-body > *:last-child { margin-bottom: 0; }

/* Headings */
.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.25;
  margin: 28px 0 16px;
  letter-spacing: -0.01em;
  scroll-margin-top: 80px;
}

.markdown-body h1 {
  font-size: 2.1em;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--border);
  margin-top: 0;
}

.markdown-body h2 {
  font-size: 1.55em;
  padding-bottom: 0.25em;
  border-bottom: 1px solid var(--border-soft);
}

.markdown-body h3 { font-size: 1.22em; }
.markdown-body h4 { font-size: 1.05em; font-family: var(--font-body); }
.markdown-body h5 { font-size: 0.92em; font-family: var(--font-body); }
.markdown-body h6 { font-size: 0.85em; color: var(--fg-muted); font-family: var(--font-body); }

/* Paragraph */
.markdown-body p { margin: 0 0 16px; }

/* Links */
.markdown-body a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.12s;
}

.markdown-body a:hover { border-bottom-color: var(--accent); }

/* Strong & em */
.markdown-body strong { font-weight: 600; color: var(--fg); }
.markdown-body em { font-family: var(--font-display); font-style: italic; }

/* Lists */
.markdown-body ul,
.markdown-body ol { padding-left: 28px; margin: 0 0 16px; }
.markdown-body li { margin: 4px 0; }
.markdown-body li > p { margin: 8px 0; }

.markdown-body ul li::marker { color: var(--accent); }
.markdown-body ol li::marker { color: var(--fg-muted); font-weight: 600; }

/* Blockquote */
.markdown-body blockquote {
  margin: 16px 0;
  padding: 4px 16px;
  border-left: 3px solid var(--accent);
  background: var(--bg-soft);
  color: var(--fg-muted);
  border-radius: 0 6px 6px 0;
}

.markdown-body blockquote p { margin: 8px 0; }

/* Inline code */
.markdown-body code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  padding: 0.2em 0.4em;
  background: var(--bg-inline-code);
  border-radius: 4px;
  color: var(--fg);
}

/* Code blocks */
.markdown-body pre {
  position: relative;
  margin: 18px 0;
  padding: 0;
  background: var(--bg-code);
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  overflow: hidden;
  font-size: 13.5px;
  box-shadow: var(--shadow-sm);
}

.markdown-body pre code {
  display: block;
  padding: 16px 18px 16px 18px;
  background: transparent;
  font-size: 13.5px;
  line-height: 1.6;
  overflow-x: auto;
  border-radius: 0;
  color: var(--fg);
}

.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 7px 14px 7px 16px;
  background: var(--bg-soft);
  border-bottom: 1px solid var(--border-soft);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--fg-muted);
  letter-spacing: 0.05em;
}

.code-lang {
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: 0.08em;
}

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 8px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  color: var(--fg-muted);
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: all 0.12s;
}

.copy-btn:hover { color: var(--accent); border-color: var(--accent); }
.copy-btn.copied { color: var(--green); border-color: var(--green); }

/* Tables */
.markdown-body table {
  border-collapse: collapse;
  margin: 18px 0;
  display: block;
  overflow-x: auto;
  width: 100%;
  font-size: 14.5px;
}

.markdown-body th,
.markdown-body td {
  padding: 8px 14px;
  border: 1px solid var(--border);
  text-align: left;
}

.markdown-body th {
  background: var(--bg-soft);
  font-weight: 600;
  font-size: 13px;
  letter-spacing: 0.01em;
}

.markdown-body tbody tr:nth-child(2n) { background: var(--table-stripe); }

/* HR */
.markdown-body hr {
  height: 1px;
  margin: 32px 0;
  background: var(--border);
  border: 0;
}

/* Images */
.markdown-body img {
  max-width: 100%;
  border-radius: 8px;
  border: 1px solid var(--border-soft);
}

/* Page footer */
.page-footer {
  border-top: 1px solid var(--border-soft);
  padding: 18px 32px;
  text-align: center;
  font-size: 12px;
  color: var(--fg-muted);
}

.page-footer a { color: var(--accent); text-decoration: none; }
.page-footer a:hover { text-decoration: underline; }

/* Anchor headings */
.markdown-body h1 .anchor,
.markdown-body h2 .anchor,
.markdown-body h3 .anchor {
  opacity: 0;
  margin-left: 8px;
  color: var(--fg-dim);
  font-size: 0.7em;
  text-decoration: none;
  transition: opacity 0.12s;
}

.markdown-body h1:hover .anchor,
.markdown-body h2:hover .anchor,
.markdown-body h3:hover .anchor { opacity: 1; }

/* Page enter animation */
.markdown-body { animation: fadeIn 0.25s ease-out; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Scrollbar */
.file-list::-webkit-scrollbar,
.toc::-webkit-scrollbar,
.markdown-body pre code::-webkit-scrollbar { width: 8px; height: 8px; }
.file-list::-webkit-scrollbar-thumb,
.toc::-webkit-scrollbar-thumb,
.markdown-body pre code::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 4px;
}
.file-list::-webkit-scrollbar-thumb:hover,
.toc::-webkit-scrollbar-thumb:hover,
.markdown-body pre code::-webkit-scrollbar-thumb:hover {
  background: var(--fg-dim);
}

/* Mobile */
@media (max-width: 980px) {
  body { grid-template-columns: 1fr; }
  .sidebar { position: fixed; transform: translateX(-100%); z-index: 100; width: 260px; transition: transform 0.2s; }
  .sidebar.open { transform: translateX(0); }
  .content-wrap { grid-template-columns: 1fr; padding: 28px 20px 60px; gap: 24px; }
  .toc { display: none; }
  .topbar { padding: 12px 20px; }
}