:root {
  --bg: #0a0614;
  --bg-2: #171025;
  --panel: #18122a;
  --panel-2: #1f1836;
  --panel-edge: #362657;
  --left: #9B4DFF;
  --down: #2B8CFF;
  --up: #22D65E;
  --right: #FF3B3B;
  --text: #f4eefc;
  --muted: #9a8bc0;
  --sick: #ffd23f;
  --good: #12FA05;
  --bad: #F9393F;
  --radius: 16px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: 'Segoe UI', 'Trebuchet MS', system-ui, sans-serif;
  overflow: hidden;
}

#bg-fx {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  z-index: 0;
  pointer-events: none;
}

#app {
  position: relative;
  z-index: 1;
  width: 100vw;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background:
    radial-gradient(ellipse 900px 500px at 18% -10%, rgba(155,77,255,0.22), transparent 60%),
    radial-gradient(ellipse 900px 500px at 85% 105%, rgba(255,59,59,0.16), transparent 60%),
    radial-gradient(ellipse at 50% 0%, #241a3d 0%, var(--bg) 62%);
}

.screen {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  animation: fadeIn 0.35s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.hidden { display: none !important; }

/* ---------- Title / branding ---------- */
.brand-wrap {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 22px;
}
.brand-mark {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--left), var(--right));
  color: white;
  box-shadow: 0 6px 22px rgba(155,77,255,0.35);
}
.brand-mark svg { width: 24px; height: 24px; }

.brand {
  font-size: 42px;
  font-weight: 900;
  letter-spacing: 2px;
  line-height: 1;
  background: linear-gradient(90deg, var(--left), var(--right));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  text-shadow: 0 0 40px rgba(255,255,255,0.12);
}
.brand-sub {
  color: var(--muted);
  font-size: 12px;
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-top: 4px;
}

/* ---------- Panel ---------- */
.panel {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--panel-edge);
  border-radius: var(--radius);
  box-shadow: 0 20px 50px rgba(0,0,0,0.4), inset 0 1px 0 rgba(255,255,255,0.04);
}
.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 18px;
  border-bottom: 1px solid var(--panel-edge);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--muted);
}

/* ---------- Song select ---------- */
#screen-select { gap: 16px; padding: 20px; }

.song-panel { width: min(520px, 90vw); }

.song-list {
  max-height: 40vh;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px;
  scrollbar-width: thin;
  scrollbar-color: var(--panel-edge) transparent;
}
.song-list::-webkit-scrollbar { width: 7px; }
.song-list::-webkit-scrollbar-thumb { background: var(--panel-edge); border-radius: 6px; }

.song-list-empty {
  color: var(--muted);
  font-size: 13px;
  text-align: center;
  padding: 22px 8px;
}

.song-card {
  background: rgba(255,255,255,0.02);
  border: 1.5px solid var(--panel-edge);
  border-radius: 12px;
  padding: 11px 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
  transition: transform 0.12s ease, border-color 0.12s ease, background 0.12s ease, box-shadow 0.12s ease;
}
.song-card:hover {
  border-color: #4a3878;
  background: rgba(255,255,255,0.045);
  transform: translateX(3px);
}
.song-card.selected {
  border-color: var(--right);
  background: linear-gradient(90deg, rgba(255,59,59,0.10), rgba(155,77,255,0.08));
  box-shadow: 0 4px 18px rgba(255,59,59,0.15);
  transform: translateX(3px);
}
.song-card-icon {
  width: 34px; height: 34px;
  flex: none;
  border-radius: 9px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255,255,255,0.05);
  color: var(--muted);
}
.song-card-icon svg { width: 18px; height: 18px; }
.song-card.selected .song-card-icon { color: var(--right); }
.song-card-body { flex: 1; min-width: 0; }
.song-title {
  font-weight: bold;
  font-size: 15px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.song-tag {
  flex: none;
  font-size: 10px;
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--bg);
  padding: 3px 8px;
  border-radius: 6px;
  font-weight: bold;
}
.tag-demo { background: var(--down); }
.tag-auto { background: var(--up); }
.tag-saved { background: var(--sick); }

.song-delete {
  flex: none;
  width: 24px; height: 24px;
  border-radius: 50%;
  border: none;
  background: rgba(255,255,255,0.06);
  color: var(--muted);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.12s ease, color 0.12s ease, transform 0.12s ease;
}
.song-delete:hover {
  background: var(--bad);
  color: white;
  transform: scale(1.08);
}

.diff-row {
  display: flex;
  gap: 10px;
  margin: 4px 0 2px;
}
.diff-btn {
  padding: 9px 22px;
  border-radius: 9px;
  border: 2px solid var(--panel-edge);
  background: var(--panel);
  color: var(--text);
  font-weight: bold;
  cursor: pointer;
  letter-spacing: 1px;
  font-size: 13px;
  transition: transform 0.1s ease, border-color 0.1s ease, box-shadow 0.1s ease;
}
.diff-btn:hover { transform: translateY(-1px); }
.diff-btn.active[data-diff="easy"] { border-color: var(--up); color: var(--up); box-shadow: 0 0 16px rgba(34,214,94,0.25); }
.diff-btn.active[data-diff="normal"] { border-color: var(--sick); color: var(--sick); box-shadow: 0 0 16px rgba(255,210,63,0.25); }
.diff-btn.active[data-diff="hard"] { border-color: var(--right); color: var(--right); box-shadow: 0 0 16px rgba(255,59,59,0.25); }

.primary-btn {
  margin-top: 6px;
  padding: 15px 44px;
  border-radius: 11px;
  border: none;
  background: linear-gradient(90deg, var(--left), var(--right));
  color: white;
  font-weight: 900;
  font-size: 16px;
  letter-spacing: 1px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  box-shadow: 0 8px 24px rgba(249,57,63,0.28);
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}
.primary-btn:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(249,57,63,0.38);
}
.primary-btn:active:not(:disabled) { transform: translateY(0); }
.primary-btn:disabled { opacity: 0.35; cursor: not-allowed; box-shadow: none; }

.upload-btn {
  padding: 7px 14px;
  border-radius: 8px;
  border: 1.5px dashed var(--panel-edge);
  background: transparent;
  color: var(--muted);
  font-weight: bold;
  font-size: 11.5px;
  letter-spacing: 0.5px;
  text-transform: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: border-color 0.12s ease, color 0.12s ease, background 0.12s ease;
}
.upload-btn:hover {
  border-color: var(--right);
  color: var(--text);
  background: rgba(255,59,59,0.06);
}

.health-row {
  width: 100%;
  display: flex;
  justify-content: center;
  margin-top: 4px;
}

.hint-text { color: var(--muted); font-size: 12px; text-align: center; max-width: 420px; line-height: 1.6; }

/* ---------- Loading ---------- */
#screen-loading { gap: 16px; }
.spinner {
  width: 48px; height: 48px;
  border-radius: 50%;
  border: 4px solid var(--panel-edge);
  border-top-color: var(--right);
  border-right-color: var(--left);
  animation: spin 0.85s cubic-bezier(0.5,0,0.5,1) infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
#loading-msg { color: var(--muted); font-size: 13px; letter-spacing: 1px; }

/* ---------- Gameplay ---------- */
#screen-game { justify-content: flex-start; padding-top: 20px; }

.hud {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 18px;
  max-width: 620px;
  gap: 10px;
}
.hud-block {
  text-align: center;
  padding: 6px 14px;
  border-radius: 10px;
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.05);
}
.hud-label { font-size: 10px; letter-spacing: 2px; color: var(--muted); text-transform: uppercase; }
.hud-value { font-size: 26px; font-weight: 900; transition: transform 0.08s ease; }
#combo-value { color: var(--sick); }

.health-wrap {
  width: 320px;
  height: 16px;
  background: #140f22;
  border: 2px solid var(--panel-edge);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: inset 0 2px 6px rgba(0,0,0,0.5);
}
#health-bar {
  height: 100%;
  width: 50%;
  background: linear-gradient(90deg, var(--right), var(--sick), var(--up));
  transition: width 0.15s ease;
}
#health-bar.health-critical {
  animation: healthPulse 0.6s ease-in-out infinite;
}
@keyframes healthPulse {
  0%, 100% { filter: brightness(1); }
  50% { filter: brightness(1.5); }
}

.highway-wrap {
  margin-top: 14px;
  padding: 3px;
  border-radius: 17px;
  background: linear-gradient(160deg, rgba(155,77,255,0.35), rgba(255,59,59,0.25));
}
#highway {
  display: block;
  border-radius: 14px;
  background: linear-gradient(180deg, #150f24, #0a0613 72%);
  box-shadow: inset 0 0 50px rgba(0,0,0,0.6);
}

.lane-legend {
  display: flex;
  gap: 22px;
  margin-top: 12px;
  font-size: 12px;
  letter-spacing: 1px;
  color: var(--muted);
  font-weight: bold;
}
.lane-legend span { display: flex; align-items: center; gap: 6px; }
.lane-legend .dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  display: inline-block;
  box-shadow: 0 0 8px currentColor;
}

.controls-hint {
  margin-top: 10px;
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 1px;
}

/* ---------- Results ---------- */
#screen-results { gap: 10px; }
.results-card {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--panel-edge);
  border-radius: 18px;
  padding: 30px 44px;
  text-align: center;
  min-width: 300px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.5);
  animation: resultsIn 0.4s cubic-bezier(0.2,0.8,0.3,1);
}
@keyframes resultsIn {
  from { opacity: 0; transform: scale(0.92) translateY(10px); }
  to { opacity: 1; transform: scale(1) translateY(0); }
}
.results-title { font-size: 26px; font-weight: 900; margin-bottom: 12px; }
.result-row { display: flex; justify-content: space-between; gap: 40px; font-size: 14px; margin: 6px 0; color: var(--muted); }
.result-row span:last-child { color: var(--text); font-weight: bold; }
.grade {
  font-size: 58px;
  font-weight: 900;
  margin: 4px 0 10px;
  background: linear-gradient(90deg, var(--left), var(--sick), var(--right));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  text-shadow: 0 0 50px rgba(255,255,255,0.15);
}
.grade-f {
  background: none;
  -webkit-background-clip: initial;
  background-clip: initial;
  color: var(--bad);
  text-shadow: 0 0 30px rgba(249,57,63,0.4);
}

/* ---------- Responsive ---------- */
@media (max-width: 560px) {
  .brand { font-size: 32px; }
  .hud-value { font-size: 20px; }
  .health-wrap { width: 220px; }
  #highway { width: 92vw; height: auto; }
  .results-card { padding: 24px 20px; min-width: 260px; }
}