*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0 }

:root {
  --bg:      #0d0d10;
  --surf:    #16161b;
  --surf2:   #1e1e26;
  --border:  #28283a;
  --accent:  #b8f050;
  --accent2: #50c8f0;
  --danger:  #f05070;
  --text:    #dddde8;
  --muted:   #60607a;
  --r:       5px;
  --mono:    'JetBrains Mono', monospace;
  --sans:    'Syne', sans-serif;
}

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: grid;
  grid-template-columns: 240px 1fr;
  grid-template-rows: 48px 1fr;
}

/* ── Top bar ── */
#topbar {
  grid-column: 1 / -1;
  background: var(--surf);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 20px;
  gap: 12px;
}
#topbar .logo {
  font-weight: 800;
  font-size: 15px;
  letter-spacing: .04em;
  color: var(--accent);
  margin-right: auto;
}
#topbar .logo span { color: var(--muted); }

/* ── Sidebar ── */
#sidebar {
  background: var(--surf);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
#sidebar-head {
  padding: 14px 16px 10px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .12em;
  color: var(--muted);
  text-transform: uppercase;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
#file-list {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0;
}

/* File item */
.file-item {
  font-size: 12.5px;
  font-family: var(--mono);
  cursor: pointer;
  border-left: 2px solid transparent;
  transition: background .1s, border-color .1s;
}
.file-item:hover { background: var(--surf2); }
.file-item.active {
  border-left-color: var(--accent);
  background: var(--surf2);
}
.file-item-row {
  display: flex;
  align-items: center;
  padding: 7px 16px;
  gap: 6px;
}
.file-item.active .fname { color: var(--accent); }
.file-item .fname { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.fcount {
  font-size: 10px;
  font-family: var(--mono);
  color: var(--accent2);
  background: rgba(80,200,240,.1);
  border: 1px solid rgba(80,200,240,.2);
  border-radius: 3px;
  padding: 1px 5px;
  white-space: nowrap;
  flex-shrink: 0;
}

.file-item .fdel {
  opacity: 0;
  background: none;
  border: none;
  color: var(--danger);
  cursor: pointer;
  font-size: 14px;
  line-height: 1;
  padding: 1px 3px;
  border-radius: 3px;
  transition: opacity .15s;
  flex-shrink: 0;
}
.file-item:hover .fdel { opacity: 1; }
.file-item .fdel:hover { background: rgba(240,80,112,.15); }

/* ── Question sub-list (sidebar) ── */
.q-sublist {
  padding: 0 12px 8px 20px;
  display: flex;
  flex-direction: column;
  gap: 3px;
  border-top: 1px solid var(--border);
  margin-top: 2px;
  padding-top: 6px;
}
.q-sub-item {
  display: flex;
  align-items: baseline;
  gap: 6px;
  padding: 3px 6px;
  border-radius: 4px;
  transition: background .1s;
}
.q-sub-item:hover { background: rgba(184,240,80,.05); }
.q-sub-n {
  font-size: 9px;
  font-family: var(--mono);
  color: var(--accent);
  font-weight: 700;
  flex-shrink: 0;
  min-width: 14px;
  text-align: right;
}
.q-sub-t {
  font-size: 11px;
  font-family: var(--mono);
  color: var(--muted);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
  transition: color .1s;
}
.q-sub-item:hover .q-sub-t { color: var(--text); }
/* Level badge in sidebar question list */
.q-sub-lvl {
  font-size: 9px;
  font-family: var(--mono);
  color: var(--accent);
  background: rgba(184,240,80,.1);
  border: 1px solid rgba(184,240,80,.2);
  border-radius: 3px;
  padding: 0 4px;
  flex-shrink: 0;
}

#no-files {
  padding: 20px 16px;
  font-size: 12px;
  color: var(--muted);
  font-family: var(--mono);
  line-height: 1.6;
}

/* ── Main ── */
#main {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Meta bar */
#meta-bar {
  padding: 14px 24px;
  border-bottom: 1px solid var(--border);
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}
#meta-bar input {
  background: var(--surf2);
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--sans);
  font-size: 13px;
  padding: 6px 10px;
  border-radius: var(--r);
  outline: none;
  transition: border-color .15s;
}
#meta-bar input:focus { border-color: var(--accent2); }
#meta-bar input[name="title"] { width: 200px; }
#meta-bar input[name="key"]   { width: 140px; }

/* Toast */
#toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  padding: 10px 18px;
  border-radius: var(--r);
  font-size: 13px;
  font-family: var(--mono);
  background: var(--surf2);
  border: 1px solid var(--border);
  color: var(--text);
  opacity: 0;
  transform: translateY(8px);
  transition: opacity .2s, transform .2s;
  pointer-events: none;
  z-index: 999;
}
#toast.show { opacity: 1; transform: translateY(0); }
#toast.ok   { border-color: var(--accent); color: var(--accent); }
#toast.err  { border-color: var(--danger); color: var(--danger); }

/* Scroll area */
#scroll {
  flex: 1;
  overflow-y: auto;
  padding: 20px 24px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

/* Question card */
.card {
  background: var(--surf);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  animation: fadeUp .2s ease;
}
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}
.card-head {
  display: flex;
  align-items: center;
  margin-bottom: 12px;
  gap: 8px;
}
.card-num {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .1em;
  color: var(--muted);
  text-transform: uppercase;
  flex: 1;
}

/* Per-question level selector */
.level-field {
  display: flex;
  align-items: center;
  gap: 5px;
  flex-shrink: 0;
}
.level-label {
  font-size: 10px;
  font-family: var(--mono);
  color: var(--muted);
  letter-spacing: .06em;
  text-transform: uppercase;
}
.level-select {
  background: var(--surf2);
  border: 1px solid var(--border);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  padding: 3px 6px;
  border-radius: var(--r);
  outline: none;
  cursor: pointer;
  transition: border-color .15s, color .15s;
}
.level-select:focus,
.level-select:hover { border-color: var(--accent); }
.level-select option { background: var(--surf2); color: var(--text); }

.del-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--muted);
  cursor: pointer;
  font-size: 12px;
  padding: 3px 8px;
  border-radius: var(--r);
  font-family: var(--mono);
  transition: border-color .15s, color .15s;
}
.del-btn:hover { border-color: var(--danger); color: var(--danger); }

input[type="text"] {
  width: 100%;
  background: var(--surf2);
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--sans);
  font-size: 13px;
  padding: 7px 10px;
  border-radius: var(--r);
  outline: none;
  transition: border-color .15s;
}
input[type="text"]:focus { border-color: var(--accent2); }

.opts-label {
  font-size: 10px;
  letter-spacing: .1em;
  color: var(--muted);
  text-transform: uppercase;
  margin: 10px 0 6px;
}
.opts { display: flex; flex-direction: column; gap: 6px; }
.opt-row { display: flex; align-items: center; gap: 8px; }
.correct-btn {
  width: 28px; height: 28px;
  border-radius: 50%;
  border: 2px solid var(--border);
  background: none;
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
  font-family: var(--mono);
  cursor: pointer;
  flex-shrink: 0;
  transition: border-color .15s, color .15s, background .15s;
}
.correct-btn:hover { border-color: var(--accent); color: var(--accent); }
.correct-btn.active {
  border-color: var(--accent);
  background: var(--accent);
  color: #0d0d10;
}
.expl-input { margin-top: 10px; }
.expl-input input { font-size: 12px; color: var(--muted); }
.expl-input input:focus { color: var(--text); }

/* Bottom action bar */
#actions {
  padding: 12px 24px;
  border-top: 1px solid var(--border);
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

/* Buttons */
.btn {
  padding: 7px 16px;
  border-radius: var(--r);
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: opacity .15s, transform .1s;
}
.btn:active { transform: scale(.97); }
.btn-accent  { background: var(--accent);  color: #0d0d10; border-color: var(--accent); }
.btn-outline { background: none; color: var(--text); border-color: var(--border); }
.btn-outline:hover { border-color: var(--accent2); color: var(--accent2); }
.btn-ghost   { background: none; color: var(--muted); border-color: transparent; }
.btn-ghost:hover { color: var(--text); }
.btn-danger  { background: none; color: var(--danger); border-color: var(--border); }
.btn-danger:hover { border-color: var(--danger); }
.btn-add {
  background: none;
  border: 1px dashed var(--border);
  color: var(--muted);
  border-radius: 8px;
  padding: 10px;
  width: 100%;
  font-family: var(--sans);
  font-size: 13px;
  cursor: pointer;
  transition: border-color .15s, color .15s;
  text-align: center;
}
.btn-add:hover { border-color: var(--accent2); color: var(--accent2); }

/* New file panel */
#new-file-row {
  padding: 10px 16px;
  border-top: 1px solid var(--border);
}
#new-file-row input {
  width: 100%;
  background: var(--surf2);
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--mono);
  font-size: 12px;
  padding: 6px 8px;
  border-radius: var(--r);
  outline: none;
  margin-bottom: 6px;
}
#new-file-row input:focus { border-color: var(--accent); }
#new-file-row .btn { width: 100%; text-align: center; }

/* Preview modal */
#modal-overlay {
  display: none;
  position: fixed; inset: 0;
  background: rgba(0,0,0,.7);
  z-index: 100;
  align-items: center;
  justify-content: center;
}
#modal-overlay.open { display: flex; }
#modal {
  background: var(--surf);
  border: 1px solid var(--border);
  border-radius: 10px;
  width: min(640px, 92vw);
  max-height: 80vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
#modal-head {
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  font-size: 13px;
  font-weight: 700;
  gap: 12px;
}
#modal-head span { flex: 1; }
#modal-body {
  flex: 1;
  overflow-y: auto;
  padding: 18px;
}
#modal-body pre {
  font-family: var(--mono);
  font-size: 12px;
  line-height: 1.7;
  color: var(--accent2);
  white-space: pre-wrap;
  word-break: break-all;
}

/* Scrollbars */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }