:root {
  --bg: #f2f2f2;
  --bg-alt: #f4f4f4;
  --surface: #ffffff;
  --surface-alt: #f7f7f7;
  --input-bg: #fafafa;
  --overlay-bg: rgba(255, 255, 255, 0.92);
  --border: #d0d0d0;
  --text: #111111;
  --muted: #5f5f5f;
  --accent: #0057ff;
}

[data-theme="dark"] {
  --bg: #111111;
  --bg-alt: #202020;
  --surface: #1c1c1c;
  --surface-alt: #252525;
  --input-bg: #1a1a1a;
  --overlay-bg: rgba(0, 0, 0, 0.92);
  --border: #333333;
  --text: #f0f0f0;
  --muted: #888888;
  --accent: #4d8aff;
}

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  transition: background 0.2s, color 0.2s;
}

/* ── Ad layout wrapper ── */
#page-layout {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  width: 100%;
  min-height: 100vh;
  gap: 16px;
}

.ad-col {
  width: 160px;
  min-width: 160px;
  position: sticky;
  top: 24px;
  align-self: flex-start;
  padding-top: 24px;
}

/* hide side ads when there's not enough room */
@media (max-width: 959px) {
  .ad-col { display: none; }
}

/* ── Mobile bottom ad bar ── */
#ad-bottom {
  display: none;
  position: fixed;
  bottom: 0; left: 0; right: 0;
  z-index: 150;
  background: var(--surface);
  border-top: 1px solid var(--border);
  text-align: center;
  min-height: 60px;
}

@media (max-width: 959px) {
  #ad-bottom { display: block; }
}

#app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px 60px;
  flex: 1;
  min-width: 0;
}

/* extra bottom padding on mobile so content clears the sticky ad */
@media (max-width: 959px) {
  #app { padding-bottom: 90px; }
}

/* ── Screens ── */
.screen { display: none; width: 100%; max-width: 500px; animation: fadeUp 0.3s ease; }
.screen.wide { max-width: 680px; }
.screen.active { display: block; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Logo / tagline ── */
.logo {
  font-size: 52px;
  font-weight: 900;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  line-height: 1;
  color: var(--text);
}
.logo em { color: var(--accent); font-style: normal; }

.tagline {
  font-size: 11px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.22em;
  margin-top: 4px;
}

/* ── Topbar ── */
.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  margin-bottom: 16px;
}
.topbar .logo { font-size: 28px; }

/* ── Card ── */
.card {
  background: var(--surface);
  border-radius: 12px;
  padding: 20px 18px 18px;
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.06);
  border: 1px solid var(--border);
  margin-bottom: 14px;
}

.card-title {
  font-size: 18px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 16px;
  color: var(--text);
}

.section-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--muted);
  margin-bottom: 8px;
}

/* ── Field ── */
.field { margin-bottom: 16px; }
.field:last-child { margin-bottom: 0; }

.field label {
  display: block;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
  margin-bottom: 6px;
}

input[type="text"],
textarea {
  width: 100%;
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 14px;
  font-size: 15px;
  color: var(--text);
  font-family: inherit;
  font-weight: 500;
  outline: none;
  transition: border-color 0.2s, background 0.2s;
}
input[type="text"]:focus,
textarea:focus {
  border-color: var(--accent);
  background: var(--surface);
}
input::placeholder, textarea::placeholder { color: var(--muted); opacity: 0.6; }
textarea { resize: vertical; min-height: 100px; line-height: 1.5; }

.code-input {
  text-transform: uppercase;
  letter-spacing: 0.25em;
  font-size: 28px;
  font-weight: 800;
  text-align: center;
}

/* ── Tabs ── */
.tabs {
  display: flex;
  gap: 4px;
  background: var(--bg-alt);
  border-radius: 10px;
  padding: 4px;
  margin-bottom: 22px;
}
.tab-btn {
  flex: 1;
  padding: 9px 8px;
  border: none;
  border-radius: 7px;
  background: transparent;
  color: var(--muted);
  font-family: inherit;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  transition: background 0.15s, color 0.15s;
}
.tab-btn.active {
  background: var(--surface);
  color: var(--text);
  box-shadow: 0 1px 6px rgba(0, 0, 0, 0.1);
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: 999px;
  border: 1px solid var(--accent);
  padding: 10px 18px;
  font-size: 14px;
  font-family: inherit;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  background: var(--accent);
  color: white;
  cursor: pointer;
  transition: background 0.15s, color 0.15s, transform 0.05s;
  outline: none;
  white-space: nowrap;
}
.btn:hover:not(:disabled) { transform: translateY(-1px); }
.btn:active:not(:disabled) { transform: translateY(0); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }

.btn-primary   { background: var(--accent); color: white; border-color: var(--accent); }
.btn-secondary { background: var(--surface); color: var(--accent); border-color: var(--accent); }
.btn-ghost     { background: transparent; color: var(--muted); border: 1px solid var(--border); }
.btn-ghost:hover:not(:disabled) { color: var(--text); border-color: var(--muted); }

.btn-full  { width: 100%; }
.btn-lg    { padding: 14px 24px; font-size: 15px; }
.btn-sm    { padding: 7px 14px; font-size: 12px; }
.btn-group { display: flex; gap: 10px; margin-top: 16px; }
.btn-group .btn { flex: 1; }

/* ── Theme toggle ── */
#theme-toggle {
  position: fixed;
  top: 16px;
  right: 16px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font-size: 18px;
  cursor: pointer;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, border-color 0.2s, transform 0.15s;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
  outline: none;
}
#theme-toggle:hover { background: var(--bg-alt); transform: scale(1.08); }

/* ── Connection status ── */
.conn-status {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 12px;
  color: var(--muted);
  font-weight: 600;
  margin-top: 10px;
  justify-content: center;
}
.conn-dot {
  width: 7px; height: 7px;
  border-radius: 50%;
  flex-shrink: 0;
  transition: background 0.3s;
}
.conn-dot.ok      { background: #22c55e; box-shadow: 0 0 5px #22c55e; }
.conn-dot.err     { background: #ef4444; }
.conn-dot.pending { background: var(--accent); animation: blink 1.2s infinite; }

@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: 0.3; } }

/* ── Toast ── */
#toast {
  position: fixed;
  top: 20px;
  right: 20px;
  transform: translateX(calc(100% + 30px));
  background: var(--surface);
  color: var(--text);
  border-radius: 10px;
  padding: 12px 16px;
  font-size: 13px;
  font-weight: 600;
  z-index: 999;
  transition: transform 0.32s cubic-bezier(0.34, 1.3, 0.64, 1);
  pointer-events: none;
  white-space: nowrap;
  box-shadow: 0 4px 20px rgba(0,0,0,0.14);
  border: 1px solid var(--border);
  border-left: 4px solid var(--border);
  display: flex;
  align-items: center;
  gap: 9px;
  max-width: 320px;
}
#toast.show     { transform: translateX(0); }
#toast.t-ok     { border-left-color: #16a34a; }
#toast.t-err    { border-left-color: #dc2626; }
#toast.t-info   { border-left-color: var(--accent); }
.toast-icon {
  font-size: 15px;
  flex-shrink: 0;
  line-height: 1;
}
#toast.t-ok   .toast-icon { color: #16a34a; }
#toast.t-err  .toast-icon { color: #dc2626; }
#toast.t-info .toast-icon { color: var(--accent); }

/* ── Countdown overlay ── */
#overlay-countdown {
  position: fixed; inset: 0;
  background: var(--overlay-bg);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 200;
}
#overlay-countdown.show { display: flex; }
.cd-num {
  font-size: 140px;
  font-weight: 900;
  color: var(--accent);
  line-height: 1;
  animation: cdPop 1s ease-out;
}
.cd-label {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.3em;
  color: var(--muted);
  margin-top: 8px;
}
@keyframes cdPop {
  0%   { transform: scale(1.4); opacity: 0; }
  25%  { transform: scale(0.95); opacity: 1; }
  100% { transform: scale(0.85); opacity: 0; }
}

/* ── Generating-questions loading state (inside countdown overlay) ── */
.cd-loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}
.cd-loading.hidden { display: none; }

.cd-spinner {
  width: 52px;
  height: 52px;
  border: 4px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: cdSpin 0.9s linear infinite;
}
@keyframes cdSpin {
  to { transform: rotate(360deg); }
}

.cd-loading-text {
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.04em;
}
.cd-loading-sub {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--muted);
}

/* ── Timer ring ── */
.timer-wrap { position: relative; width: 62px; height: 62px; flex-shrink: 0; }
.timer-wrap svg { transform: rotate(-90deg); }
.timer-wrap svg circle:first-child { stroke: var(--border); }
.timer-wrap circle { transition: stroke-dashoffset 1s linear; }
.timer-num {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 20px; font-weight: 800; color: var(--text);
  transition: color 0.3s;
}
.timer-num.urgent { color: #dc2626; }

/* ── Room code ── */
.room-code-big {
  font-size: 48px;
  font-weight: 900;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  text-align: center;
  padding: 12px 14px;
  cursor: pointer;
  user-select: none;
  transition: background 0.15s;
}
.room-code-big:hover { background: var(--surface-alt); }
.code-copy-hint {
  text-align: center;
  font-size: 11px;
  color: var(--muted);
  margin-top: 6px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* ── Player list ── */
.players-list { display: flex; flex-direction: column; gap: 6px; }

.player-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  font-size: 14px;
}
.player-item.is-you   { border-color: var(--accent); }
.player-item.answered { border-color: #22c55e; }
.player-left { display: flex; align-items: center; gap: 10px; }
.player-avatar {
  width: 28px; height: 28px; border-radius: 50%;
  background: var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 800; flex-shrink: 0;
}
.player-right { display: flex; align-items: center; gap: 8px; }
.player-score { font-size: 16px; font-weight: 800; color: var(--accent); }

.badge { font-size: 10px; font-weight: 800; text-transform: uppercase; padding: 2px 7px; border-radius: 999px; }
.badge-host { background: var(--accent); color: white; }
.badge-you  { background: var(--bg-alt); color: var(--muted); border: 1px solid var(--border); }

.answered-dot { width: 8px; height: 8px; border-radius: 50%; background: #22c55e; flex-shrink: 0; }
.answered-dot.waiting { background: var(--border); }

#player-count { font-size: 18px; font-weight: 800; color: var(--muted); }

/* ── Notice ── */
.notice {
  border-radius: 8px;
  padding: 10px 14px;
  font-size: 13px;
  font-weight: 600;
  line-height: 1.5;
  margin-top: 12px;
}
.notice-info { background: #eff6ff; color: #1d4ed8; border: 1px solid #bfdbfe; }
.notice-ok   { background: #f0fdf4; color: #15803d; border: 1px solid #bbf7d0; }
.notice-err  { background: #fef2f2; color: #b91c1c; border: 1px solid #fecaca; }
.notice.hidden { display: none; }

[data-theme="dark"] .notice-info { background: #172554; color: #93c5fd; border-color: #1e40af; }
[data-theme="dark"] .notice-ok   { background: #052e16; color: #86efac; border-color: #166534; }
[data-theme="dark"] .notice-err  { background: #450a0a; color: #fca5a5; border-color: #991b1b; }

/* ── Range slider ── */
.range-row  { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
.range-val  { font-size: 22px; font-weight: 800; color: var(--accent); min-width: 44px; text-align: right; }
.range-unit { font-size: 11px; color: var(--muted); font-weight: 700; }

input[type="range"] {
  -webkit-appearance: none;
  width: 100%; height: 4px;
  border-radius: 2px;
  background: var(--border);
  outline: none;
  margin-bottom: 4px;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 2px solid var(--surface);
  box-shadow: 0 0 0 1px var(--accent);
}
.range-hint { display: flex; justify-content: space-between; font-size: 11px; color: var(--muted); font-weight: 700; }

/* ── Upload zone ── */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: 8px;
  padding: 20px 14px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  position: relative;
}
.upload-zone:hover, .upload-zone.drag-over { border-color: var(--accent); background: var(--surface-alt); }
.upload-zone input[type="file"] { position: absolute; inset: 0; opacity: 0; cursor: pointer; width: 100%; height: 100%; }
.upload-icon { font-size: 20px; margin-bottom: 6px; }
.upload-zone p { font-size: 13px; color: var(--muted); margin: 0; }
.upload-file-name { margin-top: 8px; font-size: 12px; font-weight: 700; color: #16a34a; }

/* ── Question screen ── */
.q-topbar { display: flex; align-items: center; justify-content: space-between; margin-bottom: 18px; }
.q-progress-text { font-size: 14px; font-weight: 700; color: var(--muted); }
.q-topic-pill {
  font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.09em;
  color: var(--accent); background: var(--surface-alt); padding: 4px 10px;
  border-radius: 999px; max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
  border: 1px solid var(--border);
}
.q-text { font-size: 19px; font-weight: 700; line-height: 1.5; text-align: center; margin-bottom: 22px; color: var(--text); }

/* ── Options ── */
.options-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }

.option-btn {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  background: var(--surface-alt);
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: 14px 13px;
  font-size: 14px;
  font-weight: 600;
  font-family: inherit;
  color: var(--text);
  cursor: pointer;
  text-align: left;
  line-height: 1.35;
  min-height: 64px;
  transition: border-color 0.15s, background 0.15s, transform 0.1s;
}
.option-btn:hover:not(:disabled) { border-color: var(--accent); background: var(--surface); transform: translateY(-2px); }
.option-btn:disabled { cursor: default; }
.option-btn.selected { border-color: var(--accent); background: var(--surface); }
.option-btn.correct  { border-color: #16a34a; background: #f0fdf4; color: #15803d; }
.option-btn.wrong    { border-color: #dc2626; background: #fef2f2; color: #b91c1c; opacity: 0.8; }
.option-btn.dim      { opacity: 0.35; }

[data-theme="dark"] .option-btn.correct { background: #052e16; color: #86efac; }
[data-theme="dark"] .option-btn.wrong   { background: #450a0a; color: #fca5a5; }

.opt-letter {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 22px; height: 22px; border-radius: 5px;
  background: var(--bg-alt); font-size: 11px; font-weight: 800;
  color: var(--muted); flex-shrink: 0; margin-top: 1px;
  transition: background 0.15s, color 0.15s;
}
.option-btn.selected .opt-letter { background: var(--accent); color: white; }
.option-btn.correct  .opt-letter { background: #16a34a; color: white; }
.option-btn.wrong    .opt-letter { background: #dc2626; color: white; }

.answered-status { text-align: center; font-size: 13px; color: var(--muted); margin-top: 14px; }
.answered-status strong { color: #16a34a; }

/* ── Reveal screen ── */
.result-hero { text-align: center; padding: 14px 0 8px; }
.result-verdict {
  font-size: 48px;
  font-weight: 900;
  line-height: 1;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.result-verdict.v-correct { color: #16a34a; }
.result-verdict.v-wrong   { color: #dc2626; }
.result-points-line { font-size: 14px; color: var(--muted); margin-top: 6px; }
.result-points-line span { font-size: 18px; font-weight: 800; color: var(--accent); }

.explanation-box {
  background: var(--surface-alt);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
  padding: 12px 14px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--muted);
  margin: 14px 0;
}

/* ── Leaderboard ── */
.lb-item {
  display: flex; align-items: center; gap: 12px;
  padding: 10px 14px;
  background: var(--surface-alt);
  border-radius: 8px;
  border: 1px solid var(--border);
  margin-bottom: 8px;
}
.lb-item.lb-me { border-color: var(--accent); background: var(--surface); }
.lb-rank { font-size: 18px; font-weight: 800; color: var(--muted); min-width: 30px; }
.lb-rank.r1 { color: #ca8a04; }
.lb-rank.r2 { color: #64748b; }
.lb-rank.r3 { color: #b45309; }
.lb-name  { flex: 1; font-weight: 600; font-size: 14px; }
.lb-score { font-size: 20px; font-weight: 800; color: var(--accent); }
.lb-streak { font-size: 11px; color: #7c3aed; font-weight: 800; }

/* ── Next-question countdown ── */
.next-q-line { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); }
.next-q-line span { color: var(--accent); }

/* ── Winner section ── */
.winner-section { text-align: center; padding: 18px 0 12px; }
.winner-crown-icon { font-size: 34px; margin-bottom: 4px; }
.winner-lbl { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.2em; color: var(--muted); }
.winner-nm  { font-size: 40px; font-weight: 900; color: #ca8a04; letter-spacing: 0.03em; margin-top: 2px; }
.winner-pts { font-size: 14px; color: var(--muted); margin-top: 4px; }

/* ── Divider & spacing utils ── */
.divider { border: none; border-top: 1px solid var(--border); margin: 18px 0; }
.mt8  { margin-top: 8px; }
.mt12 { margin-top: 12px; }
.mt16 { margin-top: 16px; }
.mt20 { margin-top: 20px; }
.mb4  { margin-bottom: 4px; }
.mb8  { margin-bottom: 8px; }
.mb12 { margin-bottom: 12px; }

/* ── Responsive ── */
@media (max-width: 520px) {
  .options-grid { grid-template-columns: 1fr; }
  .q-text { font-size: 17px; }
  .btn-group { flex-direction: column; }
  .room-code-big { font-size: 38px; }
}