:root {
  --bg: #0f1115;
  --bg-elev: #171a21;
  --bg-elev-2: #1f232c;
  --border: #2a2f3a;
  --text: #e7e9ee;
  --text-dim: #9aa1ad;
  --accent: #6ea8fe;
  --accent-soft: rgba(110, 168, 254, 0.14);
  --radius: 12px;
  --maxw: 760px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", "Apple SD Gothic Neo", "Noto Sans KR", sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
}

body {
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.app {
  display: grid;
  grid-template-columns: 300px 1fr;
  height: 100vh;
}

/* ── Sidebar ───────────────────────────── */
.sidebar {
  background: var(--bg-elev);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.sidebar__head {
  padding: 20px 18px 14px;
  border-bottom: 1px solid var(--border);
}

.logo {
  margin: 0 0 14px;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.logo span {
  color: var(--accent);
  margin-left: 4px;
  font-weight: 600;
}

.search {
  width: 100%;
  padding: 9px 12px;
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  border-radius: 9px;
  color: var(--text);
  font-size: 14px;
  outline: none;
}
.search:focus {
  border-color: var(--accent);
}

.topic-list {
  overflow-y: auto;
  padding: 10px;
  flex: 1;
}

.topic-group__label {
  padding: 12px 10px 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.topic-item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  width: 100%;
  padding: 9px 11px;
  margin-bottom: 2px;
  background: transparent;
  border: none;
  border-radius: 8px;
  color: var(--text);
  font-size: 14.5px;
  text-align: left;
  cursor: pointer;
}
.topic-item:hover {
  background: var(--bg-elev-2);
}
.topic-item.is-active {
  background: var(--accent-soft);
  color: var(--accent);
}
.topic-item__count {
  font-size: 12px;
  color: var(--text-dim);
  flex-shrink: 0;
}
.topic-item.is-active .topic-item__count {
  color: var(--accent);
}

/* ── Content ───────────────────────────── */
.content {
  overflow-y: auto;
  padding: 40px 32px 80px;
}

.empty {
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: var(--text-dim);
}
.empty__title {
  font-size: 18px;
  color: var(--text);
  margin: 0 0 6px;
}
.empty__sub {
  font-size: 14px;
  margin: 0;
}

.topic-header {
  max-width: var(--maxw);
  margin: 0 auto 28px;
}
.topic-header__cat {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
}
.topic-header__title {
  margin: 6px 0 4px;
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.topic-header__title small {
  font-size: 16px;
  font-weight: 500;
  color: var(--text-dim);
  margin-left: 8px;
}
.topic-header__desc {
  margin: 8px 0 0;
  font-size: 14.5px;
  color: var(--text-dim);
  line-height: 1.6;
}

.q-list {
  max-width: var(--maxw);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.q-card {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
}
.q-card__top {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}
.q-num {
  font-size: 12px;
  font-weight: 700;
  color: var(--text-dim);
}
.q-tag {
  font-size: 11px;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--bg-elev-2);
  color: var(--text-dim);
  border: 1px solid var(--border);
}
.q-card__text {
  margin: 0;
  font-size: 16.5px;
  line-height: 1.6;
}
.q-card__note {
  margin: 10px 0 0;
  font-size: 13.5px;
  color: var(--text-dim);
  line-height: 1.55;
  padding-left: 12px;
  border-left: 2px solid var(--border);
}

.q-speak {
  margin-left: auto;
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: 8px;
  padding: 4px 10px;
  font-size: 13px;
  cursor: pointer;
}
.q-speak:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* ── Mobile back bar (데스크탑에선 숨김) ─── */
.back-bar {
  display: none;
}
.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: transparent;
  border: none;
  color: var(--accent);
  font-size: 15px;
  font-weight: 600;
  padding: 6px 4px;
  cursor: pointer;
}

/* ── Responsive: 마스터-디테일 ─────────── */
@media (max-width: 720px) {
  .app {
    grid-template-columns: 1fr;
    grid-template-rows: 1fr;
  }

  .sidebar {
    border-right: none;
    height: 100%;
    min-height: 0;
  }
  .sidebar__head {
    padding-top: max(20px, env(safe-area-inset-top));
  }

  /* 기본: 목록 보임, 본문 숨김 */
  .content {
    display: none;
    padding: 0 16px calc(64px + env(safe-area-inset-bottom));
  }

  /* 주제 선택 시: 목록 숨기고 본문 표시 */
  .app.is-detail .sidebar {
    display: none;
  }
  .app.is-detail .content {
    display: block;
  }

  .back-bar {
    display: flex;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 5;
    margin: 0 -16px 8px;
    padding: 10px 12px;
    padding-top: max(10px, env(safe-area-inset-top));
    background: rgba(15, 17, 21, 0.85);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border);
  }

  .topic-header {
    margin-top: 4px;
    margin-bottom: 20px;
  }
  .topic-header__title {
    font-size: 23px;
  }
  .topic-header__title small {
    display: block;
    margin: 4px 0 0;
    font-size: 14px;
  }

  .topic-item {
    padding: 12px 12px;
    font-size: 15.5px;
  }
  .q-card {
    padding: 16px 16px;
  }
  .q-card__text {
    font-size: 16px;
  }
}