/* ===== Reset & base ===== */
* { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0f172a;
  --bg-2: #1e293b;
  --bg-3: #334155;
  --border: #334155;
  --text: #e2e8f0;
  --text-dim: #94a3b8;
  --text-muted: #64748b;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
}

#app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 16px;
}

/* ===== Top bar ===== */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 18px;
}
.logo { font-size: 24px; }

.nav {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.nav-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-dim);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.15s;
  position: relative;
}
.nav-btn:hover { color: var(--text); background: var(--bg-2); }
.nav-btn.active {
  color: var(--text);
  background: var(--bg-2);
  border-color: var(--border);
}
.badge {
  display: inline-block;
  background: var(--accent);
  color: white;
  font-size: 11px;
  font-weight: 700;
  padding: 1px 6px;
  border-radius: 10px;
  margin-left: 4px;
  min-width: 18px;
  text-align: center;
}

/* ===== Content / views ===== */
.content { flex: 1; padding-bottom: 32px; }
.view { display: none; }
.view.active { display: block; }

h1 {
  font-size: 28px;
  margin-bottom: 8px;
  font-weight: 700;
}
h2 {
  font-size: 18px;
  margin: 28px 0 12px;
  font-weight: 600;
  color: var(--text-dim);
}
.muted { color: var(--text-muted); margin-bottom: 24px; }

/* ===== Stat grid ===== */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}
.stat-card {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.stat-label {
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-weight: 600;
}
.stat-value {
  font-size: 28px;
  font-weight: 700;
  color: var(--text);
}
.stat-card .btn { align-self: flex-start; margin-top: 4px; }

/* ===== Action grid ===== */
.action-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}
.action-card {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: left;
  cursor: pointer;
  color: var(--text);
  transition: all 0.15s;
  font-family: inherit;
}
.action-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}
.action-icon { font-size: 28px; margin-bottom: 8px; }
.action-title { font-size: 16px; font-weight: 600; margin-bottom: 4px; }
.action-desc { font-size: 13px; color: var(--text-muted); }

/* ===== Skill grid ===== */
.skill-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
}
.skill-tile {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
}
.skill-name { font-weight: 600; margin-bottom: 8px; }
.skill-stats {
  display: flex;
  gap: 12px;
  font-size: 12px;
  color: var(--text-muted);
}
.skill-bar {
  height: 6px;
  background: var(--bg-3);
  border-radius: 3px;
  margin-top: 8px;
  overflow: hidden;
}
.skill-bar-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.3s;
}

/* ===== Buttons ===== */
.btn {
  background: var(--bg-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  font-family: inherit;
  transition: all 0.15s;
}
.btn:hover { background: var(--bg-3); }
.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}
.btn.primary:hover { background: var(--accent-hover); }
.btn.success { background: var(--success); border-color: var(--success); color: white; }
.btn.warning { background: var(--warning); border-color: var(--warning); color: white; }
.btn.danger { background: var(--danger); border-color: var(--danger); color: white; }
.btn.small { padding: 6px 12px; font-size: 13px; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* ===== Filter bar ===== */
.filter-bar {
  display: flex;
  gap: 16px;
  align-items: center;
  margin-bottom: 16px;
  flex-wrap: wrap;
  font-size: 14px;
}
.filter-bar label {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--text-dim);
}
.filter-bar select {
  background: var(--bg-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 14px;
  cursor: pointer;
}

/* ===== Card list (browse) ===== */
.card-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 12px;
}
.browse-card {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
  cursor: pointer;
  transition: all 0.15s;
}
.browse-card:hover { border-color: var(--accent); }
.browse-card .front {
  font-weight: 600;
  font-size: 16px;
  margin-bottom: 6px;
}
.browse-card .meta {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 8px;
}
.browse-card .tag {
  background: var(--bg-3);
  padding: 2px 6px;
  border-radius: 3px;
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: 0.3px;
}
.browse-card .status {
  font-size: 11px;
  color: var(--text-muted);
}
.status-new { color: var(--accent); }
.status-learning { color: var(--warning); }
.status-review { color: var(--success); }

/* ===== Study area ===== */
.study-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 12px;
}
.study-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text-dim);
  font-size: 14px;
}
.study-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
  padding: 24px 0;
  min-height: 400px;
  justify-content: center;
}
.flashcard {
  width: 100%;
  max-width: 600px;
  min-height: 320px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  cursor: pointer;
  user-select: none;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
  transition: transform 0.4s;
  transform-style: preserve-3d;
}
.flashcard.flipped { transform: rotateY(180deg); }
.card-face {
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.card-face.back {
  position: absolute;
  inset: 32px;
  transform: rotateY(180deg);
}
.card-cat {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: 0.5px;
}
.card-front-text {
  font-size: 28px;
  font-weight: 600;
  text-align: center;
  padding: 24px 0;
}
.card-back-text {
  font-size: 15px;
  line-height: 1.6;
}
.card-back-text strong { color: var(--accent); }
.card-back-text .example {
  margin-top: 12px;
  padding: 10px 12px;
  background: var(--bg-3);
  border-radius: var(--radius-sm);
  font-style: italic;
  font-size: 14px;
}
.card-hint {
  text-align: center;
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 12px;
}
.grade-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
  width: 100%;
  max-width: 600px;
}
.grade-btn {
  flex: 1;
  min-width: 100px;
  padding: 12px;
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-2);
  color: var(--text);
  cursor: pointer;
  font-family: inherit;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}
.grade-btn:hover { background: var(--bg-3); }
.grade-btn .label { font-size: 14px; }
.grade-btn .next { font-size: 11px; color: var(--text-muted); }
.grade-btn.again { border-color: var(--danger); }
.grade-btn.again:hover { background: var(--danger); }
.grade-btn.hard { border-color: var(--warning); }
.grade-btn.hard:hover { background: var(--warning); }
.grade-btn.good { border-color: var(--success); }
.grade-btn.good:hover { background: var(--success); }
.grade-btn.easy { border-color: var(--accent); }
.grade-btn.easy:hover { background: var(--accent); }

.empty-state {
  text-align: center;
  color: var(--text-muted);
  padding: 48px 16px;
}
.empty-state .big { font-size: 48px; margin-bottom: 12px; }
.empty-state h2 { color: var(--text-dim); margin: 0 0 8px; }

/* ===== Quiz area ===== */
.quiz-setup {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  max-width: 600px;
}
.quiz-q {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  max-width: 700px;
  margin: 0 auto;
}
.quiz-q .q-num {
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
}
.quiz-q .q-text {
  font-size: 18px;
  font-weight: 500;
  margin-bottom: 20px;
  line-height: 1.5;
}
.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.quiz-opt {
  text-align: left;
  background: var(--bg-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 15px;
  font-family: inherit;
  transition: all 0.15s;
}
.quiz-opt:hover { border-color: var(--accent); }
.quiz-opt.correct { background: var(--success); border-color: var(--success); color: white; }
.quiz-opt.wrong { background: var(--danger); border-color: var(--danger); color: white; }
.quiz-opt:disabled { cursor: not-allowed; }
.quiz-q .feedback {
  margin-top: 16px;
  padding: 12px;
  background: var(--bg-3);
  border-radius: var(--radius-sm);
  font-size: 14px;
}
.quiz-progress {
  width: 100%;
  max-width: 700px;
  height: 6px;
  background: var(--bg-3);
  border-radius: 3px;
  overflow: hidden;
  margin: 0 auto 16px;
}
.quiz-progress-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.3s;
}
.quiz-result {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
}
.quiz-result .score {
  font-size: 56px;
  font-weight: 700;
  color: var(--accent);
  margin: 16px 0;
}
.quiz-result .pct {
  font-size: 24px;
  color: var(--text-dim);
  margin-bottom: 24px;
}

/* ===== Progress view ===== */
.bars { display: flex; flex-direction: column; gap: 10px; max-width: 600px; }
.bar-row { display: flex; align-items: center; gap: 12px; }
.bar-label { width: 110px; font-size: 14px; text-transform: capitalize; }
.bar-track {
  flex: 1;
  height: 12px;
  background: var(--bg-3);
  border-radius: 6px;
  overflow: hidden;
}
.bar-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.3s;
}
.bar-val { width: 60px; text-align: right; font-size: 13px; color: var(--text-muted); }

.chart {
  display: flex;
  gap: 4px;
  align-items: flex-end;
  height: 160px;
  padding: 8px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.chart-bar {
  flex: 1;
  background: var(--accent);
  border-radius: 3px 3px 0 0;
  min-height: 2px;
  position: relative;
  transition: height 0.3s;
}
.chart-bar:hover { background: var(--accent-hover); }
.chart-bar .lbl {
  position: absolute;
  bottom: -22px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 10px;
  color: var(--text-muted);
}
.chart-bar .val {
  position: absolute;
  top: -16px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 10px;
  color: var(--text-dim);
}

.settings {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

/* ===== Footer ===== */
.footer {
  text-align: center;
  padding: 16px 0;
  font-size: 12px;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
}

/* ===== Library view ===== */
.library-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 20px;
  align-items: start;
}

.library-sidebar {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px;
  position: sticky;
  top: 16px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
}

.library-search {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: inherit;
  margin-bottom: 12px;
}
.library-search:focus {
  outline: none;
  border-color: var(--accent);
}

.library-tree { display: flex; flex-direction: column; gap: 4px; }

.library-skill {
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.library-skill-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  cursor: pointer;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  user-select: none;
}
.library-skill-header:hover { background: var(--bg-3); }
.library-skill-icon { font-size: 16px; }
.library-skill-name { flex: 1; }
.library-skill-count {
  background: var(--bg-3);
  color: var(--text-dim);
  font-size: 11px;
  padding: 1px 6px;
  border-radius: 8px;
  font-weight: 500;
}
.library-skill-arrow {
  color: var(--text-muted);
  font-size: 10px;
  transition: transform 0.15s;
}
.library-skill.collapsed .library-skill-arrow { transform: rotate(-90deg); }
.library-skill.collapsed .library-skill-pages { display: none; }

.library-skill-pages {
  display: flex;
  flex-direction: column;
  gap: 1px;
  padding: 2px 0 6px 24px;
}

.library-page {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 10px;
  color: var(--text-dim);
  text-decoration: none;
  font-size: 13px;
  border-radius: var(--radius-sm);
  border-left: 2px solid transparent;
  transition: all 0.1s;
}
.library-page:hover {
  background: var(--bg-3);
  color: var(--text);
}
.library-page.active {
  background: var(--bg-3);
  color: var(--text);
  border-left-color: var(--accent);
}
.lp-hub {
  font-size: 9px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  background: var(--accent);
  color: white;
  padding: 1px 5px;
  border-radius: 3px;
  font-weight: 700;
}

/* Welcome state */
.library-welcome {
  padding: 20px 0;
}
.library-welcome h2 { margin-top: 0; }
.library-welcome-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin-top: 16px;
}
.library-skill-tile {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  cursor: pointer;
  color: var(--text);
  transition: all 0.15s;
  font-family: inherit;
}
.library-skill-tile:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}
.lskill-icon { font-size: 32px; margin-bottom: 8px; }
.lskill-name { font-weight: 600; font-size: 15px; margin-bottom: 4px; }
.lskill-count { font-size: 12px; color: var(--text-muted); }

/* Page article */
.page-article {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  max-width: 800px;
}
.page-header { margin-bottom: 24px; padding-bottom: 16px; border-bottom: 1px solid var(--border); }
.page-breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-weight: 600;
}
.page-skill { color: var(--text-dim); }
.page-title { font-size: 32px; font-weight: 700; margin: 4px 0 8px; line-height: 1.2; }
.page-summary {
  color: var(--text-dim);
  font-size: 16px;
  margin-bottom: 8px;
  line-height: 1.5;
}
.page-tags { display: flex; flex-wrap: wrap; gap: 4px; margin-top: 8px; }
.page-tag {
  background: var(--bg-3);
  color: var(--text-dim);
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 10px;
}

/* Page content (rendered markdown) */
.page-content {
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
}
.page-content h1, .page-content h2, .page-content h3, .page-content h4, .page-content h5, .page-content h6 {
  font-weight: 700;
  margin: 1.5em 0 0.5em;
  line-height: 1.3;
}
.page-content h1 { font-size: 24px; }
.page-content h2 {
  font-size: 20px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
}
.page-content h3 { font-size: 17px; color: var(--text); }
.page-content h4 { font-size: 15px; color: var(--text-dim); }
.page-content p { margin: 0.75em 0; }
.page-content ul, .page-content ol { margin: 0.75em 0; padding-left: 1.5em; }
.page-content li { margin: 0.25em 0; }
.page-content li > ul, .page-content li > ol { margin: 0.25em 0; }
.page-content strong { color: var(--text); font-weight: 700; }
.page-content em { color: var(--text); }
.page-content a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px dashed var(--accent);
}
.page-content a:hover { color: var(--accent-hover); border-bottom-style: solid; }
.page-content a.wiki-link {
  color: var(--text);
  background: var(--bg-3);
  padding: 1px 6px;
  border-radius: 3px;
  border-bottom: none;
  font-size: 0.95em;
}
.page-content a.wiki-link:hover { background: var(--accent); color: white; }
.page-content code {
  background: var(--bg-3);
  color: #f472b6;
  padding: 2px 6px;
  border-radius: 3px;
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.9em;
}
.page-content pre {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  overflow-x: auto;
  margin: 1em 0;
}
.page-content pre code {
  background: transparent;
  color: var(--text);
  padding: 0;
  font-size: 13px;
}
.page-content blockquote {
  border-left: 3px solid var(--accent);
  padding: 4px 16px;
  margin: 1em 0;
  background: var(--bg);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--text-dim);
}
.page-content blockquote p { margin: 0.5em 0; }
.page-content hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2em 0;
}
.page-content table {
  border-collapse: collapse;
  margin: 1em 0;
  width: 100%;
  font-size: 14px;
}
.page-content th, .page-content td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
.page-content th {
  background: var(--bg-3);
  font-weight: 700;
  color: var(--text);
}
.page-content td { color: var(--text-dim); }
.page-content tr:nth-child(even) td { background: rgba(255,255,255,0.02); }

/* Callouts (Obsidian syntax) */
.callout {
  border-left: 4px solid var(--accent);
  background: var(--bg);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 1em 0;
  overflow: hidden;
}
.callout-title {
  font-weight: 600;
  font-size: 14px;
  padding: 8px 12px;
  background: rgba(59, 130, 246, 0.1);
  color: var(--text);
}
.callout-body {
  padding: 8px 12px 12px;
  font-size: 14px;
  color: var(--text-dim);
}
.callout-body p:first-child { margin-top: 0; }
.callout-body p:last-child { margin-bottom: 0; }
.callout-note { border-left-color: #3b82f6; }
.callout-note .callout-title { background: rgba(59, 130, 246, 0.1); }
.callout-tip { border-left-color: #10b981; }
.callout-tip .callout-title { background: rgba(16, 185, 129, 0.1); }
.callout-warning { border-left-color: #f59e0b; }
.callout-warning .callout-title { background: rgba(245, 158, 11, 0.1); }
.callout-danger { border-left-color: #ef4444; }
.callout-danger .callout-title { background: rgba(239, 68, 68, 0.1); }
.callout-important { border-left-color: #8b5cf6; }
.callout-important .callout-title { background: rgba(139, 92, 246, 0.1); }
.callout-example { border-left-color: #ec4899; }
.callout-example .callout-title { background: rgba(236, 72, 153, 0.1); }
.callout-quote { border-left-color: #64748b; }
.callout-quote .callout-title { background: rgba(100, 116, 139, 0.1); }
.callout-info { border-left-color: #06b6d4; }
.callout-info .callout-title { background: rgba(6, 182, 212, 0.1); }
.callout-caution { border-left-color: #f59e0b; }
.callout-caution .callout-title { background: rgba(245, 158, 11, 0.1); }

/* Page nav (prev/next) */
.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 32px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  gap: 12px;
}
.page-nav a {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  color: var(--text-dim);
  text-decoration: none;
  font-size: 14px;
  flex: 1;
  max-width: 45%;
  transition: all 0.15s;
}
.page-nav a:hover { border-color: var(--accent); color: var(--text); }
.page-nav-prev { text-align: left; }
.page-nav-next { text-align: right; margin-left: auto; }

.page-loading {
  text-align: center;
  padding: 64px 16px;
}

/* ===== Mobile ===== */
@media (max-width: 640px) {
  h1 { font-size: 22px; }
  .nav-btn { padding: 6px 10px; font-size: 13px; }
  .flashcard { min-height: 280px; padding: 20px; }
  .card-front-text { font-size: 22px; }
  .grade-btn { min-width: 70px; padding: 10px 6px; }
  .stat-value { font-size: 22px; }
  .library-layout { grid-template-columns: 1fr; }
  .library-sidebar { position: static; max-height: none; }
  .page-article { padding: 20px; }
  .page-title { font-size: 24px; }
  .page-content { font-size: 14px; }
  .page-content table { font-size: 13px; }
  .page-content th, .page-content td { padding: 6px 8px; }
}