:root {
  --bg: #f4f6fb;
  --bg-soft: #ffffff;
  --card: #ffffff;
  --text: #1c2230;
  --text-soft: #5b657a;
  --border: #e3e8f2;
  --primary: #4f46e5;
  --primary-soft: #eef0fe;
  --n3: #0ea5e9;
  --n3-soft: #e0f2fe;
  --n2: #ec4899;
  --n2-soft: #fce7f3;
  --green: #16a34a;
  --green-soft: #dcfce7;
  --shadow: 0 4px 20px rgba(27, 34, 48, 0.08);
  --shadow-lg: 0 18px 50px rgba(27, 34, 48, 0.18);
  --radius: 16px;
}

[data-theme="dark"] {
  --bg: #0f1320;
  --bg-soft: #161b2c;
  --card: #1a2033;
  --text: #eef1f8;
  --text-soft: #9aa4bd;
  --border: #2a3148;
  --primary: #818cf8;
  --primary-soft: #232a44;
  --n3-soft: #0c2a3a;
  --n2-soft: #3a1228;
  --green-soft: #103021;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 18px 50px rgba(0, 0, 0, 0.55);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Be Vietnam Pro", "Noto Sans JP", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background .25s, color .25s;
}

.jp { font-family: "Noto Sans JP", "Be Vietnam Pro", sans-serif; }

/* ---------- Topbar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  background: linear-gradient(120deg, #4f46e5, #7c3aed 60%, #ec4899);
  color: #fff;
  box-shadow: var(--shadow);
}
.topbar-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand-logo {
  font-family: "Noto Sans JP";
  font-size: 28px;
  font-weight: 700;
  width: 46px; height: 46px;
  display: grid; place-items: center;
  background: rgba(255,255,255,.18);
  border-radius: 12px;
  backdrop-filter: blur(4px);
}
.brand-text h1 { margin: 0; font-size: 19px; font-weight: 700; letter-spacing: .2px; }
.brand-text p { margin: 0; font-size: 12.5px; opacity: .85; }
.topbar-actions { display: flex; align-items: center; gap: 10px; }
.progress-pill {
  background: rgba(255,255,255,.18);
  padding: 7px 14px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
}
.icon-btn {
  background: rgba(255,255,255,.18);
  border: none;
  color: #fff;
  width: 38px; height: 38px;
  border-radius: 10px;
  font-size: 17px;
  cursor: pointer;
  transition: background .2s;
}
.icon-btn:hover { background: rgba(255,255,255,.32); }

/* ---------- Controls ---------- */
.controls {
  position: sticky;
  top: 74px;
  z-index: 20;
  background: var(--bg-soft);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
}
.controls-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}
.search-wrap {
  position: relative;
  flex: 1 1 280px;
  min-width: 220px;
}
.search-icon {
  position: absolute;
  left: 14px; top: 50%;
  transform: translateY(-50%);
  opacity: .5;
  font-size: 15px;
}
#searchInput {
  width: 100%;
  padding: 11px 14px 11px 40px;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  background: var(--card);
  color: var(--text);
  font-size: 14.5px;
  font-family: inherit;
  outline: none;
  transition: border .2s, box-shadow .2s;
}
#searchInput:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-soft); }
.filter-group { display: flex; gap: 7px; flex-wrap: wrap; }
.chip {
  border: 1.5px solid var(--border);
  background: var(--card);
  color: var(--text-soft);
  padding: 9px 18px;
  border-radius: 11px;
  font-size: 14px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all .18s;
}
.chip:hover { border-color: var(--primary); color: var(--primary); }
.chip.active { background: var(--primary); border-color: var(--primary); color: #fff; }
.chip[data-level="N3"].active { background: var(--n3); border-color: var(--n3); }
.chip[data-level="N2"].active { background: var(--n2); border-color: var(--n2); }
.chip-sm {
  border: 1.5px solid var(--border);
  background: var(--card);
  color: var(--text-soft);
  padding: 8px 14px;
  border-radius: 10px;
  font-size: 13px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all .18s;
}
.chip-sm:hover { border-color: var(--primary); color: var(--primary); }
.chip-sm.active { background: var(--text); border-color: var(--text); color: var(--bg-soft); }
#quizBtn { border-color: var(--primary); color: var(--primary); }
#quizBtn:hover { background: var(--primary); color: #fff; }

/* ---------- Container / grid ---------- */
.container { max-width: 1180px; margin: 0 auto; padding: 22px 20px 60px; }
.result-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  color: var(--text-soft);
  font-size: 13.5px;
  font-weight: 500;
}
.sort-select {
  padding: 7px 12px;
  border: 1.5px solid var(--border);
  border-radius: 9px;
  background: var(--card);
  color: var(--text);
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
}
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}
.lesson-header {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin: 14px 0 2px;
  padding: 10px 16px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-left: 5px solid var(--primary);
  border-radius: 10px;
  font-weight: 700;
  font-size: 15px;
  color: var(--text);
}
.lesson-header:first-child { margin-top: 0; }
.lesson-header .lh-count { font-size: 12px; font-weight: 600; color: var(--text-soft); }

.card {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  cursor: pointer;
  position: relative;
  transition: transform .16s, box-shadow .16s, border-color .16s;
  overflow: hidden;
}
.card::before {
  content: "";
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 5px;
  background: var(--primary);
}
.card.lv-N3::before { background: var(--n3); }
.card.lv-N2::before { background: var(--n2); }
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); border-color: transparent; }
.card-top { display: flex; justify-content: space-between; align-items: flex-start; gap: 10px; margin-bottom: 8px; }
.card-title {
  font-family: "Noto Sans JP";
  font-size: 22px;
  font-weight: 700;
  margin: 0;
  color: var(--text);
}
.badge {
  font-size: 11px;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 999px;
  letter-spacing: .3px;
  white-space: nowrap;
}
.badge.N3 { background: var(--n3-soft); color: var(--n3); }
.badge.N2 { background: var(--n2-soft); color: var(--n2); }
.card-reading { font-size: 12.5px; color: var(--text-soft); margin: 0 0 6px; }
.card-meaning { font-size: 14.5px; color: var(--text); margin: 0; font-weight: 500; }
.card-en { font-size: 12.5px; color: var(--text-soft); margin: 4px 0 0; font-style: italic; }
.card-learned-mark {
  position: absolute;
  top: 12px; right: 12px;
  display: none;
}
.card.learned { border-color: var(--green); }
.card.learned .card-learned-mark { display: block; color: var(--green); font-size: 16px; }
.card.learned .badge { opacity: .6; }

.empty-state { text-align: center; padding: 60px 20px; color: var(--text-soft); font-size: 16px; }

/* ---------- Modal ---------- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 19, 32, .55);
  backdrop-filter: blur(3px);
  z-index: 50;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 40px 16px;
  overflow-y: auto;
}
.modal-overlay[hidden] { display: none; }
.modal {
  background: var(--bg-soft);
  border-radius: 20px;
  max-width: 760px;
  width: 100%;
  padding: 30px 32px 36px;
  position: relative;
  box-shadow: var(--shadow-lg);
  animation: pop .22s ease;
}
@keyframes pop { from { transform: translateY(14px) scale(.98); opacity: 0; } to { transform: none; opacity: 1; } }
.modal-close {
  position: absolute;
  top: 16px; right: 16px;
  width: 36px; height: 36px;
  border: none;
  background: var(--border);
  color: var(--text);
  border-radius: 10px;
  font-size: 15px;
  cursor: pointer;
  transition: background .2s;
}
.modal-close:hover { background: var(--n2); color: #fff; }

/* ---------- Detail content ---------- */
.detail-head { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; margin-bottom: 4px; padding-right: 40px; }
.detail-title { font-family: "Noto Sans JP"; font-size: 34px; font-weight: 700; margin: 0; }
.detail-reading { color: var(--text-soft); font-size: 15px; margin: 2px 0 0; }
.detail-meaning { font-size: 19px; font-weight: 600; margin: 14px 0 2px; color: var(--primary); }
.detail-en { color: var(--text-soft); font-size: 14px; font-style: italic; margin: 0 0 18px; }

.section { margin-bottom: 22px; }
.section h3 {
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: .6px;
  color: var(--text-soft);
  margin: 0 0 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.section h3::before { content: ""; width: 4px; height: 16px; background: var(--primary); border-radius: 4px; }
.structure-box {
  background: var(--primary-soft);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
  font-family: "Noto Sans JP";
  font-size: 16px;
  font-weight: 500;
  white-space: pre-wrap;
}
.explain-text { font-size: 15px; color: var(--text); margin: 0; }
.notes-list { margin: 0; padding-left: 0; list-style: none; }
.notes-list li {
  position: relative;
  padding: 8px 8px 8px 30px;
  font-size: 14.5px;
  border-bottom: 1px dashed var(--border);
}
.notes-list li:last-child { border-bottom: none; }
.notes-list li::before {
  content: "💡";
  position: absolute;
  left: 4px; top: 8px;
  font-size: 13px;
}
.example {
  background: var(--card);
  border: 1px solid var(--border);
  border-left: 4px solid var(--n3);
  border-radius: 10px;
  padding: 13px 16px;
  margin-bottom: 11px;
}
.example .jp-sentence { font-family: "Noto Sans JP"; font-size: 16.5px; font-weight: 500; margin: 0 0 4px; }
.example .reading { font-size: 12.5px; color: var(--text-soft); margin: 0 0 6px; }
.example .vi-sentence { font-size: 14px; color: var(--text); margin: 0; }
.example .vi-sentence::before { content: "→ "; color: var(--n3); font-weight: 700; }

.related-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.related-tag {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: 9px;
  padding: 6px 12px;
  font-family: "Noto Sans JP";
  font-size: 14px;
  cursor: pointer;
  transition: all .18s;
}
.related-tag:hover { border-color: var(--primary); color: var(--primary); }

.detail-actions { display: flex; gap: 10px; margin-top: 8px; }
.btn-primary, .btn-secondary {
  border: none;
  padding: 11px 20px;
  border-radius: 11px;
  font-size: 14px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all .18s;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { filter: brightness(1.08); }
.btn-secondary { background: var(--border); color: var(--text); }
.btn-secondary:hover { filter: brightness(.96); }
.btn-learned { background: var(--green); color: #fff; }

/* ---------- Flashcard ---------- */
.quiz-modal { max-width: 760px; text-align: center; }
.quiz-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; color: var(--text-soft); font-weight: 600; }
.anki-counts { display: flex; gap: 12px; font-size: 15px; font-weight: 700; letter-spacing: 0.5px; }
.count-new { color: #3b82f6; }
.count-learn { color: #ef4444; }
.count-review { color: #22c55e; }
.flashcard {
  min-height: 240px;
  background: var(--primary-soft);
  border: 2px solid var(--border);
  border-radius: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 28px;
  margin-bottom: 18px;
  cursor: pointer;
}
.flashcard-front .fc-title { font-family: "Noto Sans JP"; font-size: 40px; font-weight: 700; margin: 0; }
.flashcard-front .fc-hint { color: var(--text-soft); font-size: 13px; margin-top: 12px; }
.flashcard-back { text-align: left; width: 100%; max-height: 50vh; overflow-y: auto; padding-right: 8px; margin-top: 16px; padding-top: 16px; border-top: 1px dashed var(--border); }
.quiz-controls { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }

/* Anki Buttons */
.anki-controls { display: flex; width: 100%; gap: 10px; }
.anki-btn {
  flex: 1;
  border: none;
  padding: 12px 0;
  border-radius: 11px;
  font-size: 14px;
  font-weight: 600;
  color: #fff;
  cursor: pointer;
  transition: filter .18s;
}
.anki-btn:hover { filter: brightness(1.1); }
.anki-again { background: #ef4444; }
.anki-hard { background: #f97316; }
.anki-good { background: #22c55e; }
.anki-easy { background: #3b82f6; }

/* ---------- Comparison Modal ---------- */
.compare-modal { max-width: 960px; }
.compare-header { margin-bottom: 24px; border-bottom: 1px solid var(--border); padding-bottom: 16px; }
.compare-group { margin-bottom: 32px; background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 20px; box-shadow: var(--shadow); }
.compare-group h3 { margin: 0 0 8px; color: var(--primary); font-size: 20px; }
.compare-table { width: 100%; border-collapse: collapse; margin-top: 12px; }
.compare-table td, .compare-table th { padding: 12px 14px; border: 1px solid var(--border); vertical-align: top; font-size: 14.5px; }
.compare-table tr:nth-child(even) { background: var(--bg); }
.compare-body { max-height: 65vh; overflow-y: auto; padding-right: 8px; }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 24px 20px;
  text-align: center;
  color: var(--text-soft);
  font-size: 12.5px;
  max-width: 1180px;
  margin: 0 auto;
}

@media (max-width: 640px) {
  .controls { top: 70px; }
  .brand-text p { display: none; }
  .modal { padding: 24px 20px 28px; }
  .detail-title { font-size: 28px; }
  .topbar-inner { padding: 12px 14px; }
  .controls-inner { padding: 12px 14px; }
}