:root {
  --ink: #1c2430;
  --ink-soft: #4a5568;
  --muted: #6b7785;
  --paper: #f7f4ef;
  --card: rgba(255, 252, 247, 0.92);
  --line: #ddd4c6;
  --accent: #0f6e56;
  --accent-deep: #0b5340;
  --accent-soft: #d8f3e7;
  --warn: #b45309;
  --danger: #b42318;
  --ok: #067647;
  --shadow: 0 18px 50px rgba(28, 36, 48, 0.08);
  --radius: 18px;
  --font: "Noto Sans SC", "DM Sans", sans-serif;
  --mono: "DM Sans", "Noto Sans SC", sans-serif;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  min-height: 100%;
  font-family: var(--font);
  color: var(--ink);
  background: var(--paper);
}

button, input, textarea, select {
  font: inherit;
}

.app-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(1200px 600px at 10% -10%, #d9eee4 0%, transparent 55%),
    radial-gradient(900px 500px at 100% 0%, #f0e2cf 0%, transparent 50%),
    linear-gradient(180deg, #fbf8f2 0%, #f3efe7 45%, #ebe4d8 100%);
}

.app-bg::after {
  content: "";
  position: absolute;
  inset: 0;
  opacity: 0.35;
  background-image:
    linear-gradient(rgba(15, 110, 86, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(15, 110, 86, 0.04) 1px, transparent 1px);
  background-size: 28px 28px;
  mask-image: linear-gradient(180deg, #000 0%, transparent 85%);
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 28px;
  backdrop-filter: blur(14px);
  background: rgba(251, 248, 242, 0.82);
  border-bottom: 1px solid rgba(221, 212, 198, 0.8);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
}

.brand-mark {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: linear-gradient(145deg, var(--accent), #178a6b);
  color: #fff;
  font-weight: 700;
  letter-spacing: 0.04em;
  box-shadow: 0 10px 24px rgba(15, 110, 86, 0.28);
}

.brand-name {
  font-weight: 700;
  font-size: 1.05rem;
  line-height: 1.2;
}

.brand-sub {
  font-size: 0.78rem;
  color: var(--muted);
  margin-top: 2px;
}

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

.nav-btn {
  border: 1px solid transparent;
  background: transparent;
  color: var(--ink-soft);
  padding: 8px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: 0.2s ease;
}

.nav-btn:hover {
  background: rgba(15, 110, 86, 0.08);
  color: var(--accent-deep);
}

.nav-btn.is-active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 8px 18px rgba(15, 110, 86, 0.22);
}

.main {
  width: min(1120px, calc(100% - 32px));
  margin: 28px auto 64px;
  animation: fadeUp 0.45s ease both;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: none; }
}

.footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.82rem;
  padding: 0 16px 28px;
}

/* Home */
.hero {
  display: grid;
  gap: 22px;
  margin-bottom: 28px;
}

.hero h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.hero p {
  margin: 0;
  max-width: 46ch;
  color: var(--ink-soft);
  font-size: 1.05rem;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.btn {
  appearance: none;
  border: none;
  border-radius: 12px;
  padding: 12px 18px;
  cursor: pointer;
  font-weight: 600;
  transition: 0.2s ease;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 10px 24px rgba(15, 110, 86, 0.25);
}

.btn-primary:hover {
  background: var(--accent-deep);
  transform: translateY(-1px);
}

.btn-ghost {
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid var(--line);
  color: var(--ink);
}

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

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.stat-grid, .bank-grid, .setup-grid {
  display: grid;
  gap: 14px;
}

.stat-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.bank-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.panel, .stat-card, .bank-card, .q-card, .result-card {
  background: var(--card);
  border: 1px solid rgba(221, 212, 198, 0.9);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.stat-card {
  padding: 18px;
}

.stat-card .label {
  color: var(--muted);
  font-size: 0.85rem;
}

.stat-card .value {
  margin-top: 8px;
  font-size: 1.7rem;
  font-weight: 700;
  font-family: var(--mono);
  color: var(--accent-deep);
}

.section-title {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 12px;
  margin: 28px 0 14px;
}

.section-title h2 {
  margin: 0;
  font-size: 1.25rem;
}

.section-title p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.bank-card {
  padding: 20px;
  display: grid;
  gap: 12px;
  transition: 0.25s ease;
}

.bank-card:hover {
  transform: translateY(-3px);
  border-color: rgba(15, 110, 86, 0.35);
}

.bank-card h3 {
  margin: 0;
  font-size: 1.15rem;
}

.meta {
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.6;
}

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

.chip {
  display: inline-flex;
  align-items: center;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-size: 0.78rem;
  font-weight: 600;
}

.chip.neutral {
  background: #efe8dc;
  color: #5c5040;
}

.chip.warn {
  background: #fff1dd;
  color: var(--warn);
}

/* Browse */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 16px;
  align-items: center;
}

.select, .search {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.85);
  border-radius: 12px;
  padding: 10px 12px;
  min-width: 140px;
  color: var(--ink);
}

.search {
  flex: 1;
  min-width: 200px;
}

.q-list {
  display: grid;
  gap: 12px;
}

.q-card {
  padding: 18px 18px 14px;
}

.q-head {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-bottom: 10px;
}

.q-stem {
  font-size: 1.02rem;
  line-height: 1.7;
  white-space: pre-wrap;
  margin-bottom: 12px;
}

.q-options {
  display: grid;
  gap: 8px;
  margin-bottom: 10px;
}

.option, .option-btn {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.65);
  text-align: left;
  line-height: 1.55;
}

.option-btn {
  width: 100%;
  cursor: pointer;
  transition: 0.15s ease;
}

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

.option-btn.is-selected {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.option-btn.is-correct {
  border-color: var(--ok);
  background: #e8f8ef;
}

.option-btn.is-wrong {
  border-color: var(--danger);
  background: #fdecec;
}

.answer-box {
  margin-top: 8px;
  padding: 10px 12px;
  border-radius: 12px;
  background: #eef7f2;
  color: var(--accent-deep);
  font-size: 0.92rem;
  line-height: 1.6;
  white-space: pre-wrap;
}

.answer-box.ref {
  background: #fff7eb;
  color: #7a4b12;
}

.answer-box.feedback-ok {
  background: #e8f8ef;
  color: var(--ok);
  animation: feedbackIn 0.25s ease;
}

.answer-box.feedback-bad {
  background: #fdecec;
  color: var(--danger);
  animation: feedbackIn 0.25s ease;
}

@keyframes feedbackIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

.option-btn:disabled {
  cursor: default;
  opacity: 1;
}

.q-nav-btn.is-correct-nav {
  background: #e8f8ef;
  border-color: #99d8b8;
}

.q-nav-btn.is-wrong-nav {
  background: #fdecec;
  border-color: #f0a8a8;
  color: var(--danger);
}

.blank-input, .essay-input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
  background: rgba(255, 255, 255, 0.8);
  resize: vertical;
}

.essay-input {
  min-height: 120px;
}

/* Practice */
.setup-grid {
  grid-template-columns: 1.2fr 0.8fr;
}

.setup-panel, .practice-side {
  padding: 22px;
}

.field {
  display: grid;
  gap: 8px;
  margin-bottom: 16px;
}

.field label {
  font-weight: 600;
  font-size: 0.92rem;
}

.check-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}

.check {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.7);
}

.practice-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 16px;
  align-items: start;
}

.practice-nav {
  position: sticky;
  top: 86px;
  padding: 16px;
}

.progress-line {
  height: 8px;
  border-radius: 999px;
  background: #e7dfd2;
  overflow: hidden;
  margin: 10px 0 14px;
}

.progress-line > span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #25a37d);
  width: 0;
  transition: width 0.25s ease;
}

.q-nav-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 6px;
}

.q-nav-btn {
  aspect-ratio: 1;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
  cursor: pointer;
  font-size: 0.82rem;
  font-weight: 600;
}

.q-nav-btn.is-current {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent-deep);
}

.q-nav-btn.is-answered {
  background: #e8f8ef;
  border-color: #99d8b8;
}

.practice-body {
  padding: 22px;
}

.practice-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.result-card {
  padding: 28px;
  text-align: center;
}

.score-ring {
  width: 140px;
  height: 140px;
  margin: 8px auto 18px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background:
    radial-gradient(circle at center, var(--card) 58%, transparent 59%),
    conic-gradient(var(--accent) var(--p, 0%), #e7dfd2 0);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--accent-deep);
}

.result-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  margin: 20px 0;
  text-align: left;
}

.result-stats .stat-card {
  box-shadow: none;
}

.review-list {
  display: grid;
  gap: 12px;
  text-align: left;
  margin-top: 18px;
}

.muted {
  color: var(--muted);
}

.loading, .error {
  padding: 48px 20px;
  text-align: center;
  color: var(--muted);
}

.error {
  color: var(--danger);
}

@media (max-width: 900px) {
  .stat-grid, .bank-grid, .setup-grid, .practice-layout, .result-stats {
    grid-template-columns: 1fr;
  }

  .topbar {
    padding: 12px 16px;
    flex-direction: column;
    align-items: stretch;
  }

  .nav {
    justify-content: space-between;
  }

  .practice-nav {
    position: static;
  }
}