:root {
  --bg: #0b0f16;
  --card: #141a24;
  --card-alt: #0d1219;
  --border: #262e3b;
  --text: #e8edf5;
  --muted: #8b96a8;
  --accent: #6ea8fe;
  --accent-dim: rgba(110, 168, 254, .12);
  --pos: #4bc98a;
  --warn: #e0a63f;
  --danger: #f0685f;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

/* header / brand */
header { padding: 28px 32px 0; }
.brand { display: flex; align-items: flex-start; gap: 14px; }
.brand-mark {
  font-size: 22px; color: var(--accent); line-height: 1;
  width: 40px; height: 40px; display: flex; align-items: center; justify-content: center;
  background: var(--accent-dim); border-radius: 10px; flex: none;
}
h1 { margin: 0; font-size: 21px; letter-spacing: -.01em; }
.sub { color: var(--muted); margin: 6px 0 0; max-width: 640px; font-size: 13.5px; line-height: 1.5; }

/* tabs */
.tabs { display: flex; gap: 4px; margin: 22px 0 0; border-bottom: 1px solid var(--border); }
.tab {
  background: none; border: none; color: var(--muted);
  padding: 10px 18px; font-size: 13.5px; cursor: pointer;
  border-bottom: 2px solid transparent; margin-bottom: -1px;
  transition: color .12s;
}
.tab:hover { color: var(--text); }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); font-weight: 600; }

/* training view */
.view { padding: 24px 32px 44px; }
#view-train, #view-admin { max-width: 980px; }
#view-train .card, #view-admin .card { margin-bottom: 18px; }
.lead { font-size: 15px; margin: 0 0 14px; }
.note {
  font-size: 12.5px; color: var(--muted); background: var(--card-alt);
  border-left: 3px solid var(--border); padding: 9px 12px; border-radius: 0 8px 8px 0; margin-top: 14px;
}
.axis-explainer { display: grid; grid-template-columns: 1.3fr 1fr; gap: 22px; align-items: center; }
@media (max-width: 820px) { .axis-explainer { grid-template-columns: 1fr; } }
.axis-list { list-style: none; padding: 0; margin: 0; font-size: 13px; }
.axis-list li { margin-bottom: 14px; color: var(--muted); }
.ax { display: block; color: var(--text); font-weight: 600; margin-bottom: 2px; }
.ax.x { color: var(--accent); }
.ax.y { color: var(--pos); }
.ax.b { color: var(--warn); }

.examples { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
@media (max-width: 900px) { .examples { grid-template-columns: 1fr; } }
.example { background: var(--card-alt); border: 1px solid var(--border); border-radius: 10px; padding: 12px; }
.example h3 { margin: 10px 0 6px; font-size: 14.5px; }
.example h3.pos { color: var(--pos); }
.example ul { padding-left: 18px; margin: 0; font-size: 12.5px; color: var(--muted); }
.example li { margin-bottom: 5px; }
.exCanvas { width: 100%; height: auto; background: #090d13; border: 1px solid var(--border); border-radius: 8px; }

button { font-family: inherit; }
button.secondary {
  background: #1b2230; border: 1px solid var(--border); color: var(--text);
  padding: 9px 18px; border-radius: 8px; cursor: pointer; font-size: 13.5px; margin-top: 10px;
  transition: border-color .12s, background .12s;
}
button.secondary:hover { border-color: var(--accent); background: #202838; }
.ghost-btn {
  background: transparent; border: 1px solid var(--border); color: var(--muted);
  padding: 6px 12px; border-radius: 20px; cursor: pointer; font-size: 12.5px;
  transition: all .12s;
}
.ghost-btn:hover { border-color: var(--warn); color: var(--warn); }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

main {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  padding: 20px 32px 44px;
}
main[hidden] { display: none; }
@media (max-width: 900px) { main { grid-template-columns: 1fr; } }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 22px;
}

.row { display: flex; align-items: center; gap: 10px; }
.row[hidden] { display: none; }
.between { justify-content: space-between; }

input, textarea {
  background: var(--card-alt);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: 8px 10px;
  font-size: 14px;
  font-family: inherit;
}
input:focus, textarea:focus, .code-editor:focus { outline: none; border-color: var(--accent); }
textarea { width: 100%; min-height: 54px; margin-top: 10px; resize: vertical; }

canvas {
  width: 100%;
  height: auto;
  background: #090d13;
  border: 1px solid var(--border);
  border-radius: 10px;
  margin: 12px 0 4px;
}

.hint, .q { color: var(--muted); font-size: 13px; }
.q { color: var(--text); font-weight: 600; margin-top: 16px; font-size: 14.5px; }

.buttons { display: flex; flex-wrap: wrap; gap: 10px; }
.buttons button {
  flex: 1 1 40%;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #1b2230;
  color: var(--text);
  font-size: 14px;
  cursor: pointer;
  transition: all .12s;
}
.buttons button:hover { border-color: var(--accent); transform: translateY(-1px); }

/* branching question-tree MCQ, each option shows a pair of reference light curves */
.optionGrid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin-top: 12px; }
@media (max-width: 700px) { .optionGrid { grid-template-columns: 1fr; } }
.optionCard {
  border: 1px solid var(--border); border-radius: 12px; padding: 12px;
  background: var(--card-alt); display: flex; flex-direction: column; gap: 9px;
  transition: border-color .12s;
}
.optionCard:hover { border-color: #3a4456; }
.optThumbs { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; }
.optThumb {
  width: 100%; height: auto; background: #070a0f;
  border: 1px solid var(--border); border-radius: 8px; margin: 0;
}
.optAnswer {
  padding: 10px; border-radius: 8px; border: 1px solid var(--border);
  background: #1b2230; color: var(--text); font-size: 13.5px; cursor: pointer;
  text-transform: capitalize; transition: all .12s; font-weight: 500;
}
.optAnswer:hover { border-color: var(--accent); background: var(--accent-dim); color: var(--accent); }

.pill {
  background: #1b2230; border: 1px solid var(--border);
  padding: 4px 12px; border-radius: 20px; font-size: 12px; color: var(--muted);
}
.status { min-height: 18px; font-size: 13px; color: var(--pos); }

.stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin-bottom: 18px; }
.stat { background: var(--card-alt); border: 1px solid var(--border); border-radius: 10px; padding: 14px; }
.stat b { display: block; font-size: 22px; }
.stat span { color: var(--muted); font-size: 12px; }

/* personal stats strip (Review tab, above the grid) */
.mystats {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px;
  padding: 0 32px; margin: 0 0 20px;
}
.mystat {
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  padding: 16px; text-align: center;
}
.mystat b { display: block; font-size: 24px; color: var(--accent); }
.mystat span { color: var(--muted); font-size: 12px; }

.tag {
  font-size: 11px; background: rgba(224,166,63,.15); color: var(--warn);
  padding: 2px 8px; border-radius: 10px; font-weight: 500;
}
.anoms { list-style: none; padding: 0; margin: 0; }
.anoms li {
  border: 1px solid var(--border); border-left: 3px solid var(--warn);
  border-radius: 8px; padding: 9px 12px; margin-bottom: 8px; font-size: 13px;
}
.anom-item { cursor: pointer; transition: background .12s; }
.anom-item:hover { background: #1a2130; }

.guide {
  margin: 10px 0 4px; font-size: 13px; color: var(--muted);
  background: var(--card-alt); border: 1px solid var(--border); border-radius: 10px; padding: 9px 12px;
}
.guide summary { cursor: pointer; color: var(--accent); font-weight: 600; }
.guide ul { margin: 8px 0 2px; padding-left: 18px; }
.guide li { margin-bottom: 4px; }

h2, h3 { margin: 0 0 12px; }
h3 { margin-top: 10px; font-size: 14.5px; }

/* admin: question-tree JSON editor */
.code-editor {
  width: 100%; min-height: 340px; margin-top: 10px; resize: vertical;
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 12.5px; line-height: 1.6; white-space: pre;
}

/* admin: votes-per-day bar chart */
.bars { display: flex; align-items: flex-end; gap: 6px; height: 90px; margin-top: 10px; }
.bar-col { display: flex; flex-direction: column; align-items: center; justify-content: flex-end; flex: 1; height: 100%; }
.bar { width: 100%; max-width: 18px; background: var(--accent); border-radius: 3px 3px 0 0; min-height: 2px; }
.bar-col span { font-size: 9.5px; color: var(--muted); margin-top: 4px; writing-mode: vertical-rl; }