:root {
  --bg: #f6f7fb;
  --card: #ffffff;
  --text: #1c1f26;
  --muted: #646b7a;
  --line: #d9dce4;
  --accent: #2f4fd8;
  --accent-soft: #e8ecfd;
  --good: #1e8a4c;
  --good-soft: #e3f4ea;
  --bad: #c43838;
  --bad-soft: #fbe7e7;
  --radius: 12px;
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 "Source Serif 4", Georgia, serif;
}
.ui, button, input, select, .top, .nav, .admin { font-family: Inter, system-ui, -apple-system, "Segoe UI", sans-serif; }
.hidden { display: none !important; }

.top {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; gap: 12px;
  padding: 12px 20px; background: var(--card); border-bottom: 1px solid var(--line);
}
.top .title { font-weight: 700; }
.top .who { color: var(--muted); font-size: 14px; margin-left: auto; }
.timer { font-variant-numeric: tabular-nums; font-weight: 600; font-size: 14px; background: var(--accent-soft); color: var(--accent); padding: 4px 10px; border-radius: 999px; }

.wrap { max-width: 820px; margin: 0 auto; padding: 24px 16px 120px; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; }
h1 { font-family: Inter, system-ui, sans-serif; font-size: 26px; margin: 0 0 6px; }
.sub { color: var(--muted); margin: 0 0 22px; font-family: Inter, system-ui, sans-serif; font-size: 15px; }

label { display: block; font: 600 14px Inter, system-ui, sans-serif; margin: 14px 0 6px; }
input[type=text], input[type=email], input[type=password], select {
  width: 100%; padding: 11px 13px; font-size: 16px; border: 1px solid var(--line);
  border-radius: 9px; background: #fff; color: var(--text);
}
input:focus, select:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: transparent; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 10px 22px; border-radius: 999px; border: 0; cursor: pointer;
  background: var(--accent); color: #fff; font-weight: 600; font-size: 15px;
}
.btn:hover { filter: brightness(1.08); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.ghost { background: transparent; color: var(--accent); border: 1px solid var(--accent); }
.btn.block { width: 100%; margin-top: 22px; }
.err { color: var(--bad); font: 14px Inter, system-ui, sans-serif; margin-top: 10px; min-height: 1em; }

/* Question */
.qhead {
  display: flex; align-items: center; gap: 12px; background: #eef0f4;
  border-bottom: 3px solid; border-image: linear-gradient(90deg,#e8453c,#f2a93b,#f4d03f,#5cc96b,#2fb7c8,#3b6be8,#8e44ec,#e84393) 1;
  padding: 0 12px 0 0; margin: -28px -28px 22px; border-radius: var(--radius) var(--radius) 0 0;
}
.qnum { background: #111; color: #fff; font: 700 20px Inter, sans-serif; padding: 8px 14px; border-top-left-radius: var(--radius); }
.qmod { font: 500 14px Inter, sans-serif; color: var(--muted); }
.qmark { margin-left: auto; font: 500 14px Inter, sans-serif; background: none; border: 0; cursor: pointer; color: var(--text); }
.qmark.on { color: #c47a00; }
.qtext { font-size: 18px; margin-bottom: 20px; }
.qtext .eq { text-align: center; margin: 6px 0 16px; line-height: 2.2; }
.qtable { border-collapse: collapse; margin: 14px auto; }
.qtable th, .qtable td { border: 1px solid #333; padding: 6px 24px; text-align: center; }
.graph { display: block; width: 100%; max-width: 420px; margin: 0 auto 16px; color: #111; }
.graph .grid { stroke: #222; stroke-width: .7; }
.graph .axis { stroke: #111; stroke-width: 1.6; }
.graph .plot { stroke: #111; stroke-width: 4; }
.graph text { font: 14px "Source Serif 4", Georgia, serif; fill: #111; paint-order: stroke; stroke: #fff; stroke-width: 4px; }

.choice {
  display: flex; align-items: center; gap: 14px; width: 100%; text-align: left;
  border: 1.5px solid #555; border-radius: 10px; background: #fff; padding: 13px 16px;
  margin-bottom: 12px; cursor: pointer; font: inherit; font-size: 17px; color: var(--text);
}
.choice:hover { background: #f4f5f8; }
.choice .letter {
  flex: none; width: 28px; height: 28px; border-radius: 50%; border: 1.5px solid #555;
  display: grid; place-items: center; font: 600 13px Inter, sans-serif;
}
.choice.sel { border-color: var(--accent); box-shadow: 0 0 0 2px var(--accent); background: var(--accent-soft); }
.choice.sel .letter { background: var(--accent); border-color: var(--accent); color: #fff; }

.gridin input { max-width: 170px; font-size: 20px; text-align: center; border: 1.5px solid #555; border-radius: 10px; padding: 14px; }
.preview { margin-top: 12px; font: 600 15px Inter, sans-serif; }
.preview span { font-family: "Source Serif 4", Georgia, serif; font-weight: 400; font-size: 20px; margin-left: 8px; }
.hint { color: var(--muted); font: 13px Inter, sans-serif; margin-top: 8px; }

/* Bottom bar */
.nav {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 5;
  display: flex; align-items: center; gap: 10px; padding: 12px 20px;
  background: var(--card); border-top: 1px solid var(--line);
}
.nav .pill { margin: 0 auto; background: #111; color: #fff; border: 0; border-radius: 8px; padding: 9px 16px; font-weight: 700; cursor: pointer; }
.nav .right { display: flex; gap: 10px; }

.palette {
  position: fixed; left: 50%; bottom: 72px; transform: translateX(-50%); z-index: 6;
  width: min(560px, calc(100% - 32px)); background: #fff; border: 1px solid var(--line);
  border-radius: 14px; padding: 18px; box-shadow: 0 12px 40px rgba(0,0,0,.18);
}
.palette h3 { margin: 0 0 4px; font: 700 15px Inter, sans-serif; }
.palette .legend { font: 12px Inter, sans-serif; color: var(--muted); margin-bottom: 10px; }
.palette .grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(42px, 1fr)); gap: 8px; margin-bottom: 12px; }
.palette .cell {
  height: 40px; border-radius: 8px; border: 1.5px dashed #888; background: #fff;
  font: 600 14px Inter, sans-serif; cursor: pointer; position: relative; color: var(--text);
}
.palette .cell.ans { background: var(--accent); border: 1.5px solid var(--accent); color: #fff; }
.palette .cell.cur { outline: 2px solid #111; outline-offset: 2px; }
.palette .cell.mark::after { content: ""; position: absolute; top: -4px; right: -4px; width: 10px; height: 10px; border-radius: 50%; background: #e0a100; }

.done { text-align: center; }
.big { font: 800 56px Inter, sans-serif; color: var(--accent); margin: 14px 0 4px; }

.modal-bg { position: fixed; inset: 0; background: rgba(10,12,20,.45); display: grid; place-items: center; z-index: 10; padding: 16px; }
.modal { background: #fff; border-radius: 14px; padding: 24px; max-width: 420px; width: 100%; font-family: Inter, system-ui, sans-serif; }
.modal h3 { margin: 0 0 8px; }
.modal p { color: var(--muted); margin: 0 0 18px; }
.modal .row { display: flex; gap: 10px; justify-content: flex-end; }

@media (max-width: 560px) {
  .card { padding: 20px; }
  .qhead { margin: -20px -20px 18px; }
  .qtext { font-size: 17px; }
  .nav { padding: 10px 12px; }
  .nav .btn { padding: 9px 14px; }
  .top .who { display: none; }
}