:root {
  --bg: #f7f7f8;
  --surface: #ffffff;
  --surface-2: #f0f1f4;
  --border: #e2e4ea;
  --text: #1a1a2e;
  --muted: #6b7280;
  --accent: #1f4e79;
  --accent-soft: #e6efff;
  --highlight: #fff3a3;
  --highlight-text: #4a3a00;
  --done: #9aa3b2;
  --danger: #b91c1c;
  --ok: #15803d;
  --warn: #b45309;
  --shadow: 0 1px 2px rgba(0,0,0,.04), 0 4px 12px rgba(0,0,0,.06);
}

[data-theme="dark"] {
  --bg: #0b1220;
  --surface: #121a2b;
  --surface-2: #182338;
  --border: #233149;
  --text: #e6eaf2;
  --muted: #98a2b3;
  --accent: #7cb0ff;
  --accent-soft: #1a2c4a;
  --highlight: #4a3a00;
  --highlight-text: #ffe684;
  --done: #5a6478;
  --danger: #fca5a5;
  --ok: #86efac;
  --warn: #fcd34d;
  --shadow: 0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.4);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 15px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  -webkit-text-size-adjust: 100%;
  min-height: 100vh;
}

.hidden { display: none !important; }

/* ---------- Login ---------- */
.login {
  position: fixed; inset: 0;
  display: grid; place-items: center;
  background: var(--bg);
  padding: 16px;
  z-index: 10;
}
.login-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  width: 100%; max-width: 360px;
  box-shadow: var(--shadow);
  display: grid; gap: 12px;
}
.login-card h1 { margin: 0; color: var(--accent); font-size: 22px; }
.login-card p { margin: 0; color: var(--muted); font-size: 14px; }
.login-card input {
  font: inherit;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
}
.login-card button {
  font: inherit; font-weight: 600;
  padding: 10px 12px;
  border: 0;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
}
.login-card button:hover { filter: brightness(1.05); }
.error { color: var(--danger); font-size: 13px; min-height: 1em; }

/* ---------- Top bar ---------- */
.topbar {
  position: sticky; top: 0;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 10px 14px 8px;
  z-index: 5;
  box-shadow: 0 1px 0 var(--border);
}
.topbar-row {
  display: flex; align-items: center; gap: 8px;
}
.topbar-row + .topbar-row { margin-top: 8px; }
.brand { margin: 0; font-size: 17px; color: var(--accent); }
.spacer { flex: 1; }
.overall {
  font-variant-numeric: tabular-nums;
  font-size: 13px; color: var(--muted);
  padding: 4px 8px;
  background: var(--surface-2);
  border-radius: 999px;
}
.icon-btn {
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text);
  width: 36px; height: 36px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 16px;
}
.icon-btn:hover { background: var(--accent-soft); }
#search {
  width: 100%;
  padding: 10px 12px;
  font: inherit;
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.sync-status {
  font-size: 12px;
  color: var(--muted);
  min-height: 16px;
  margin-top: 6px;
}
.sync-status.error { color: var(--danger); }

/* ---------- Content ---------- */
.content {
  max-width: 880px;
  margin: 0 auto;
  padding: 12px 12px 80px;
}
.empty {
  padding: 32px 16px;
  text-align: center;
  color: var(--muted);
}

/* domain / subcategory cards */
details.domain, details.subcat {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  margin-bottom: 10px;
  box-shadow: var(--shadow);
  overflow: hidden;
}
details.domain > summary,
details.subcat > summary {
  cursor: pointer;
  padding: 12px 14px;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 6px;
  user-select: none;
}
details.domain > summary::-webkit-details-marker,
details.subcat > summary::-webkit-details-marker { display: none; }
details.domain > summary { background: linear-gradient(0deg, transparent, var(--accent-soft) 200%); }
details.domain > summary .title {
  font-weight: 700; font-size: 15px;
  letter-spacing: .02em;
  color: var(--accent);
}
details.subcat { border-radius: 8px; margin: 0 10px 10px; }
details.subcat > summary .title {
  font-weight: 600; font-size: 14px;
  color: var(--text);
}
.summary-row {
  display: flex; align-items: center; gap: 10px;
  width: 100%;
}
.caret {
  width: 10px; flex: 0 0 10px;
  transition: transform 0.15s;
  color: var(--muted);
}
details[open] > summary .caret { transform: rotate(90deg); }
.count {
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  color: var(--muted);
  background: var(--surface-2);
  padding: 2px 8px;
  border-radius: 999px;
}

.progress {
  height: 6px;
  background: var(--surface-2);
  border-radius: 999px;
  overflow: hidden;
  flex: 1;
  min-width: 80px;
}
.progress > span {
  display: block;
  height: 100%;
  background: var(--accent);
  border-radius: 999px;
  transition: width 0.2s ease;
}

.subcats {
  padding: 10px 0 4px;
}

/* terms */
.terms { padding: 0; }
.term {
  display: grid;
  grid-template-columns: auto 1fr auto;
  grid-template-areas:
    "chk name star"
    "chk def  star";
  gap: 4px 10px;
  padding: 10px 14px;
  border-top: 1px solid var(--border);
  align-items: start;
}
.term:first-child { border-top: 0; }
.term input[type=checkbox] {
  grid-area: chk;
  width: 18px; height: 18px;
  margin-top: 3px;
  accent-color: var(--accent);
  cursor: pointer;
}
.term .name {
  grid-area: name;
  font-weight: 600;
  word-break: break-word;
}
.term .def {
  grid-area: def;
  color: var(--muted);
  font-size: 14px;
}
.term .star {
  grid-area: star;
  background: transparent;
  border: 0;
  color: var(--muted);
  font-size: 18px;
  cursor: pointer;
  padding: 2px 6px;
  line-height: 1;
}
.term .star.on { color: #eab308; }
.term.done .name { color: var(--done); text-decoration: line-through; }
.term.done .def { opacity: .6; }
.term.highlighted { background: var(--highlight); }
.term.highlighted .name,
.term.highlighted .def { color: var(--highlight-text); }
.term mark {
  background: #ffeb3b; color: #1a1a2e; padding: 0 2px; border-radius: 2px;
}
[data-theme="dark"] .term mark { background: #facc15; }

/* ---------- Flashcard modal ---------- */
.modal {
  position: fixed; inset: 0;
  background: rgba(0,0,0,.4);
  display: grid; place-items: center;
  padding: 16px;
  z-index: 20;
}
.modal-card {
  background: var(--surface);
  border-radius: 12px;
  width: 100%;
  max-width: 520px;
  max-height: calc(100vh - 32px);
  box-shadow: var(--shadow);
  display: flex; flex-direction: column;
  overflow: hidden;
}
.modal-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
}
.modal-head h2 { margin: 0; font-size: 17px; color: var(--accent); }

.fc-setup {
  padding: 14px;
  display: grid; gap: 12px;
}
.fc-setup label {
  display: flex; align-items: center; gap: 8px;
  font-size: 14px;
}
.fc-setup label.checkbox { gap: 8px; }
.fc-setup select {
  flex: 1;
  font: inherit;
  padding: 8px 10px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  border-radius: 8px;
}
button.primary {
  background: var(--accent);
  color: #fff;
  border: 0;
  padding: 10px 14px;
  border-radius: 8px;
  font: inherit; font-weight: 600;
  cursor: pointer;
}
.fc-setup #fc-start { justify-self: start; }

.fc-play { display: flex; flex-direction: column; }
.fc-counter {
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  padding: 8px 0;
}
.fc-card {
  margin: 0 14px;
  min-height: 220px;
  border: 1px solid var(--border);
  background: var(--surface-2);
  border-radius: 10px;
  padding: 18px;
  display: grid;
  place-content: center;
  text-align: center;
  cursor: pointer;
  user-select: none;
}
.fc-face { font-size: 18px; font-weight: 600; line-height: 1.4; }
#fc-back { color: var(--muted); font-weight: 500; }
.fc-hint { color: var(--muted); font-size: 12px; margin-top: 12px; }
.fc-actions {
  display: flex; gap: 8px; justify-content: center;
  padding: 12px 14px;
}
.fc-actions button {
  flex: 1;
  padding: 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font: inherit;
  cursor: pointer;
}
.fc-actions button.primary { border-color: transparent; }
.fc-session {
  display: flex; flex-wrap: wrap; gap: 8px;
  padding: 0 14px 14px;
}
.fc-session button {
  flex: 1 1 120px;
  padding: 8px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font: inherit;
  cursor: pointer;
}
.fc-session button.ok { color: var(--ok); }
.fc-session button.warn { color: var(--warn); }

@media (min-width: 720px) {
  .term {
    grid-template-columns: auto 280px 1fr auto;
    grid-template-areas: "chk name def star";
    align-items: center;
  }
  .term .name { font-size: 15px; }
}