/* ---------------------------------------------------------------------
   Design tokens
--------------------------------------------------------------------- */
:root {
  --bg: #f6f6fb;
  --bg-elevated: #ffffff;
  --bg-sunken: #ececf5;
  --text: #17172b;
  --text-muted: #6b6b85;
  --border: #e2e2ee;
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-fg: #ffffff;
  --accent: #8b5cf6;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --warning: #d97706;
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 20px;
  --shadow: 0 1px 2px rgba(20, 20, 50, 0.06), 0 4px 16px rgba(20, 20, 50, 0.06);
  --shadow-lg: 0 8px 30px rgba(20, 20, 50, 0.14);
  --header-h: 56px;
  --font-jp: "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", "Noto Sans JP", sans-serif;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #101018;
    --bg-elevated: #191925;
    --bg-sunken: #0b0b12;
    --text: #f1f1fa;
    --text-muted: #9a9ab0;
    --border: #2b2b3d;
    --primary: #818cf8;
    --primary-hover: #a5b4fc;
    --primary-fg: #14142b;
    --accent: #c4b5fd;
    --success: #4ade80;
    --success-bg: #0f2d1c;
    --danger: #f87171;
    --danger-bg: #3a1414;
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #101018;
  --bg-elevated: #191925;
  --bg-sunken: #0b0b12;
  --text: #f1f1fa;
  --text-muted: #9a9ab0;
  --border: #2b2b3d;
  --primary: #818cf8;
  --primary-hover: #a5b4fc;
  --primary-fg: #14142b;
  --accent: #c4b5fd;
  --success: #4ade80;
  --success-bg: #0f2d1c;
  --danger: #f87171;
  --danger-bg: #3a1414;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, var(--font-jp);
  -webkit-font-smoothing: antialiased;
  overscroll-behavior-y: none;
}
:lang(ja), .jp, ruby, rt { font-family: var(--font-jp); }
button { font-family: inherit; }
a { color: var(--primary); }

/* language toggle spans baked into extracted content: default to English */
.en { display: inline; }
.ja { display: none; }

/* ---------------------------------------------------------------------
   App shell
--------------------------------------------------------------------- */
#app { min-height: 100%; display: flex; flex-direction: column; }

header.app-header {
  position: sticky; top: 0; z-index: 20;
  height: var(--header-h);
  display: flex; align-items: center; gap: 8px;
  padding: 0 8px 0 4px;
  background: color-mix(in srgb, var(--bg-elevated) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-btn {
  display: flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: 999px; border: none;
  background: transparent; color: var(--text); cursor: pointer; flex-shrink: 0;
}
.header-btn:hover { background: var(--bg-sunken); }
.header-title-wrap { flex: 1; min-width: 0; }
.header-title { font-weight: 700; font-size: 16px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.header-subtitle { font-size: 12px; color: var(--text-muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

main { flex: 1; padding: 16px 16px 96px; max-width: 880px; width: 100%; margin: 0 auto; }

.icon { width: 20px; height: 20px; display: inline-block; }
.icon svg { width: 100%; height: 100%; fill: currentColor; }

/* ---------------------------------------------------------------------
   Home screen
--------------------------------------------------------------------- */
.hero {
  padding: 28px 4px 20px;
}
.hero h1 { margin: 0 0 4px; font-size: 26px; letter-spacing: -0.02em; }
.hero p { margin: 0; color: var(--text-muted); font-size: 14px; }

.book-group { margin-top: 22px; }
.book-group h2 {
  font-size: 13px; text-transform: uppercase; letter-spacing: 0.06em;
  color: var(--text-muted); margin: 0 0 10px 2px; font-weight: 700;
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}
@media (min-width: 560px) { .lesson-grid { grid-template-columns: repeat(3, 1fr); } }
@media (min-width: 820px) { .lesson-grid { grid-template-columns: repeat(4, 1fr); } }

.lesson-card {
  display: block; text-align: left; text-decoration: none; color: inherit;
  background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px; cursor: pointer; position: relative; overflow: hidden;
  box-shadow: var(--shadow); transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.lesson-card:active { transform: scale(0.97); }
@media (hover: hover) {
  .lesson-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-2px); }
}
.lesson-card .lesson-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 30px; height: 30px; border-radius: 9px; font-weight: 800; font-size: 13px;
  background: linear-gradient(135deg, var(--primary), var(--accent)); color: #fff;
  margin-bottom: 10px;
}
.lesson-card .lesson-name { font-weight: 700; font-size: 13.5px; line-height: 1.3; margin: 0 0 4px; }
.lesson-card .lesson-pages { font-size: 11px; color: var(--text-muted); }
.lesson-card .lesson-progress-ring {
  position: absolute; top: 12px; right: 12px; width: 22px; height: 22px;
}

/* ---------------------------------------------------------------------
   Lesson activity list
--------------------------------------------------------------------- */
.section-group { margin-bottom: 22px; }
.section-group h3 {
  font-size: 14px; margin: 0 0 8px 2px; display: flex; align-items: center; gap: 8px;
  color: var(--text);
}
.section-group h3 .count { font-weight: 400; color: var(--text-muted); font-size: 12px; }

.activity-list { display: flex; flex-direction: column; gap: 8px; }
.activity-row {
  display: flex; align-items: center; gap: 12px;
  background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius-sm);
  padding: 12px 14px; text-decoration: none; color: inherit; cursor: pointer;
}
.activity-row:active { background: var(--bg-sunken); }
.activity-row .a-title { flex: 1; font-size: 14px; font-weight: 600; }
.activity-row .a-desc { font-size: 12px; color: var(--text-muted); margin-top: 2px; }
.activity-row .a-check {
  width: 22px; height: 22px; border-radius: 999px; border: 2px solid var(--border);
  flex-shrink: 0; display: flex; align-items: center; justify-content: center;
}
.activity-row.done .a-check { background: var(--success); border-color: var(--success); color: #fff; }
.activity-row .badge {
  font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.03em;
  padding: 3px 7px; border-radius: 999px; background: var(--bg-sunken); color: var(--text-muted);
  flex-shrink: 0;
}

/* ---------------------------------------------------------------------
   Buttons
--------------------------------------------------------------------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  border: none; border-radius: 999px; padding: 11px 20px; font-size: 14px; font-weight: 700;
  cursor: pointer; background: var(--bg-sunken); color: var(--text);
  transition: filter 0.1s ease, transform 0.1s ease;
}
.btn:active { transform: scale(0.96); }
.btn-primary { background: var(--primary); color: var(--primary-fg); }
.btn-primary:hover { background: var(--primary-hover); }
.btn-ghost { background: transparent; border: 1px solid var(--border); }
.btn:disabled { opacity: 0.4; cursor: default; }
.btn-block { width: 100%; }

.action-bar {
  position: sticky; bottom: 0; display: flex; gap: 10px; justify-content: center;
  padding: 12px 16px calc(12px + env(safe-area-inset-bottom));
  background: color-mix(in srgb, var(--bg) 85%, transparent); backdrop-filter: blur(10px);
  border-top: 1px solid var(--border);
}

/* ---------------------------------------------------------------------
   Activity player shell
--------------------------------------------------------------------- */
.player-info {
  background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 16px; margin-bottom: 16px; font-size: 14px; line-height: 1.6;
}
.mode-tabs { display: flex; gap: 6px; overflow-x: auto; margin-bottom: 16px; padding-bottom: 2px; }
.mode-tab {
  flex-shrink: 0; border: 1px solid var(--border); background: var(--bg-elevated); color: var(--text-muted);
  padding: 8px 14px; border-radius: 999px; font-size: 13px; font-weight: 700; cursor: pointer;
}
.mode-tab.active { background: var(--primary); color: var(--primary-fg); border-color: var(--primary); }

.progress-track { height: 5px; background: var(--bg-sunken); border-radius: 999px; overflow: hidden; margin-bottom: 18px; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--primary), var(--accent)); border-radius: 999px; transition: width 0.25s ease; }

/* ---------------------------------------------------------------------
   Flashcards
--------------------------------------------------------------------- */
.flashcard-stage { display: flex; flex-direction: column; align-items: center; padding: 10px 0 24px; }
.flashcard {
  width: 100%; max-width: 420px; height: 260px; perspective: 1200px; cursor: pointer;
}
.flashcard-inner {
  position: relative; width: 100%; height: 100%; transition: transform 0.45s cubic-bezier(.4,.2,.2,1);
  transform-style: preserve-3d;
}
.flashcard.flipped .flashcard-inner { transform: rotateY(180deg); }
.flashcard-face {
  position: absolute; inset: 0; backface-visibility: hidden;
  display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center;
  border-radius: var(--radius-lg); box-shadow: var(--shadow-lg); padding: 20px;
  background: var(--bg-elevated); border: 1px solid var(--border);
}
.flashcard-face.back { transform: rotateY(180deg); background: linear-gradient(155deg, var(--primary), var(--accent)); color: #fff; border: none; }
.flashcard-face .fc-main { font-size: 40px; font-weight: 700; }
.flashcard-face .fc-sub { margin-top: 10px; font-size: 15px; opacity: 0.85; }
.flashcard-hint { margin-top: 14px; font-size: 12px; color: var(--text-muted); }
.flashcard-controls { display: flex; gap: 12px; margin-top: 20px; }
.fc-round-btn {
  width: 54px; height: 54px; border-radius: 999px; border: none; cursor: pointer;
  display: flex; align-items: center; justify-content: center; font-size: 20px;
  background: var(--bg-elevated); box-shadow: var(--shadow); border: 1px solid var(--border); color: var(--text);
}
.fc-round-btn.know { color: var(--success); }
.fc-round-btn.dontknow { color: var(--danger); }

/* ---------------------------------------------------------------------
   Multi-choice
--------------------------------------------------------------------- */
.mcq-question { font-size: 17px; font-weight: 600; margin-bottom: 16px; line-height: 1.5; }
.mcq-options { display: flex; flex-direction: column; gap: 10px; }
.mcq-option {
  text-align: left; padding: 14px 16px; border-radius: var(--radius-sm);
  border: 1.5px solid var(--border); background: var(--bg-elevated); cursor: pointer; font-size: 14.5px;
  display: flex; align-items: center; gap: 10px;
}
.mcq-option:active { background: var(--bg-sunken); }
.mcq-option .opt-letter {
  width: 24px; height: 24px; border-radius: 7px; background: var(--bg-sunken); color: var(--text-muted);
  display: flex; align-items: center; justify-content: center; font-size: 12px; font-weight: 800; flex-shrink: 0;
}
.mcq-option.correct { border-color: var(--success); background: var(--success-bg); }
.mcq-option.correct .opt-letter { background: var(--success); color: #fff; }
.mcq-option.incorrect { border-color: var(--danger); background: var(--danger-bg); }
.mcq-option.incorrect .opt-letter { background: var(--danger); color: #fff; }
.mcq-option[disabled] { cursor: default; }

/* ---------------------------------------------------------------------
   Matching
--------------------------------------------------------------------- */
.match-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.match-col { display: flex; flex-direction: column; gap: 8px; }
.match-item {
  padding: 12px; border-radius: var(--radius-sm); border: 1.5px solid var(--border);
  background: var(--bg-elevated); cursor: pointer; font-size: 13.5px; text-align: center; min-height: 44px;
  display: flex; align-items: center; justify-content: center;
}
.match-item.selected { border-color: var(--primary); background: color-mix(in srgb, var(--primary) 12%, var(--bg-elevated)); }
.match-item.matched { border-color: var(--success); background: var(--success-bg); opacity: 0.6; cursor: default; pointer-events: none; }
.match-item.wrong { border-color: var(--danger); background: var(--danger-bg); }

/* ---------------------------------------------------------------------
   Fill-in-the-blank / template content
--------------------------------------------------------------------- */
.template-content { font-size: 15px; line-height: 2.1; }
.template-row { margin-bottom: 14px; }
.template-row:last-child { margin-bottom: 0; }
.template-content p, .template-content .sectionDesc3rd { margin: 0 0 12px; }
.blank-input {
  border: none; border-bottom: 2px solid var(--border); background: transparent;
  font-size: 15px; padding: 2px 4px; text-align: center; color: var(--text);
  font-family: inherit; min-width: 2.4em;
}
.blank-input:focus { outline: none; border-color: var(--primary); }
.blank-input.correct { border-color: var(--success); color: var(--success); font-weight: 700; }
.blank-input.incorrect { border-color: var(--danger); color: var(--danger); }
.blank-hint { font-size: 10px; color: var(--text-muted); display: block; margin-top: -4px; }

.lesson-image { display: inline-block; margin: 8px 4px; }
.lesson-image img { max-width: 100%; border-radius: var(--radius-sm); box-shadow: var(--shadow); }
.audio-block { margin: 10px 0; }
.audio-block audio { width: 100%; max-width: 340px; }
.grammar-ref {
  background: var(--bg-sunken); color: var(--primary); border-radius: 6px; padding: 1px 6px;
  font-size: 0.92em; cursor: help; border-bottom: 1px dashed var(--primary);
}

/* legacy content-authoring classes (from the source corpus) restyled for this app */
.problem, .inline-problem, .example-problem { margin: 10px 0; }
.count-problems { counter-reset: problem; }
.count-problems > .problem { counter-increment: problem; }
.count-problems > .problem::before { content: counter(problem) ". "; font-weight: 700; color: var(--text-muted); }
.inner-problem { padding-left: 6px; }
.sectionDesc3rd { display: block; font-weight: 700; margin: 18px 0 8px; }
.sectionDesc3rd:first-child { margin-top: 0; }
.sectionNumber3rd {
  display: inline-flex; width: 22px; height: 22px; border-radius: 6px; background: var(--primary); color: #fff;
  align-items: center; justify-content: center; font-size: 12px; margin-right: 8px;
}
.clear::after { content: ""; display: block; clear: both; }
.columns-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 6px 16px; }
.valign-top { vertical-align: top; }
.center { text-align: center; }
.left { text-align: left; }
.right { text-align: right; }
.label, .med-label, .big-label, .sm-label { font-weight: 700; color: var(--text-muted); font-size: 0.9em; }
.inline-columns { display: flex; flex-wrap: wrap; gap: 6px 18px; }
.sub-section { margin: 14px 0; padding: 10px 12px; background: var(--bg-sunken); border-radius: var(--radius-sm); }
.inline-furi, .furigana { font-size: 0.7em; color: var(--text-muted); }
.kana-box {
  display: inline-flex; align-items: center; justify-content: center; min-width: 34px; height: 34px;
  border: 1px solid var(--border); border-radius: 6px; margin: 2px; font-size: 16px;
}
.small-margin { margin: 4px 0; }
.big-margin { margin: 20px 0; }
.no-margin { margin: 0; }
.ul-double { columns: 2; }
.block { display: block; }
.section-desc, .section-title { font-weight: 700; margin: 4px 0 10px; }
.indent-block { margin-left: 18px; padding-left: 10px; border-left: 2px solid var(--border); }
.button-top { margin-top: 10px; }
.large-width { width: 100%; }
.spoiler { filter: blur(5px); transition: filter 0.15s ease; cursor: pointer; }
.spoiler:hover, .spoiler.revealed { filter: none; }
.t-bold { font-weight: 700; }
.t-green { color: var(--success); }
.t-red { color: var(--danger); }
.vocab-key { font-weight: 700; }
.side-border { border-left: 2px solid var(--border); padding-left: 10px; }
.vertical-text { writing-mode: vertical-rl; }
.bubbles { display: flex; flex-direction: column; gap: 10px; }
.bubble-number {
  display: inline-flex; width: 22px; height: 22px; border-radius: 999px; background: var(--bg-sunken);
  align-items: center; justify-content: center; font-size: 12px; margin-right: 8px; font-weight: 700;
}
.text-block, .text-passage { line-height: 2; }
.count-alpha { list-style-type: lower-alpha; padding-left: 20px; }

table.table { border-collapse: collapse; width: 100%; margin: 10px 0; font-size: 14px; }
table.table td, table.table th { border: 1px solid var(--border); padding: 8px 10px; text-align: center; }
table.table small { color: var(--text-muted); display: block; }

ruby rt { font-size: 0.6em; color: var(--text-muted); }
:root[data-furigana="hidden"] rt,
:root[data-furigana="hidden"] .furigana,
:root[data-furigana="hidden"] .inline-furi { display: none; }

/* ---------------------------------------------------------------------
   Stroke / reference view (v1: reference-only, no canvas recognition)
--------------------------------------------------------------------- */
.stroke-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(110px, 1fr)); gap: 12px; }
.stroke-card {
  background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 10px; text-align: center;
}
.stroke-card img { width: 100%; border-radius: 6px; background: #fff; }
.stroke-card .sc-strokes { font-size: 11px; color: var(--text-muted); margin-top: 4px; }
.notice-banner {
  background: var(--bg-sunken); border-radius: var(--radius-sm); padding: 10px 14px; font-size: 12.5px;
  color: var(--text-muted); margin-bottom: 14px;
}

/* ---------------------------------------------------------------------
   Result / score panel
--------------------------------------------------------------------- */
.result-panel { text-align: center; padding: 30px 16px; }
.result-panel .score { font-size: 46px; font-weight: 800; background: linear-gradient(135deg, var(--primary), var(--accent)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.result-panel p { color: var(--text-muted); margin: 6px 0 20px; }

/* ---------------------------------------------------------------------
   Empty / loading states
--------------------------------------------------------------------- */
.loading, .empty-state { text-align: center; padding: 60px 20px; color: var(--text-muted); }
.spinner {
  width: 28px; height: 28px; border-radius: 999px; border: 3px solid var(--border);
  border-top-color: var(--primary); animation: spin 0.8s linear infinite; margin: 0 auto 12px;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---------------------------------------------------------------------
   Settings sheet
--------------------------------------------------------------------- */
.sheet-backdrop {
  position: fixed; inset: 0; background: rgba(0,0,0,0.4); z-index: 40;
  display: flex; align-items: flex-end; justify-content: center;
}
@media (min-width: 640px) { .sheet-backdrop { align-items: center; } }
.sheet {
  background: var(--bg-elevated); width: 100%; max-width: 440px; border-radius: 20px 20px 0 0;
  padding: 20px; max-height: 80vh; overflow-y: auto;
}
@media (min-width: 640px) { .sheet { border-radius: 20px; } }
.sheet h2 { margin: 0 0 16px; font-size: 17px; }
.setting-row { display: flex; align-items: center; justify-content: space-between; padding: 12px 0; border-bottom: 1px solid var(--border); }
.setting-row:last-child { border-bottom: none; }
.switch { position: relative; width: 46px; height: 26px; }
.switch input { opacity: 0; width: 0; height: 0; }
.switch .track { position: absolute; inset: 0; background: var(--bg-sunken); border-radius: 999px; cursor: pointer; transition: background 0.15s; }
.switch .track::before { content: ""; position: absolute; width: 20px; height: 20px; left: 3px; top: 3px; background: #fff; border-radius: 999px; transition: transform 0.15s; box-shadow: 0 1px 3px rgba(0,0,0,0.3); }
.switch input:checked + .track { background: var(--primary); }
.switch input:checked + .track::before { transform: translateX(20px); }
.theme-options { display: flex; gap: 8px; }
.theme-options button { flex: 1; padding: 8px; border-radius: var(--radius-sm); border: 1.5px solid var(--border); background: var(--bg); color: var(--text); cursor: pointer; font-size: 12px; font-weight: 700; }
.theme-options button.active { border-color: var(--primary); color: var(--primary); }

@media (max-width: 380px) { main { padding: 12px 12px 90px; } }