* { box-sizing: border-box; }

[hidden] { display: none !important; }

:root {
  --bg: #070b12;
  --panel: #0d131e;
  --line: rgba(255, 255, 255, 0.08);
  --text: #dfe6ef;
  --dim: rgba(223, 230, 239, 0.55);
  --blue: #3fa9ff;
  --green: #2fe6a0;
  --amber: #ffd479;
  --red: #ff7a7a;
}

html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

.app-shell {
  height: 100%;
  display: flex;
  flex-direction: column;
}

.topbar {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: 0.8rem 1.2rem;
  border-bottom: 1px solid var(--line);
}

.back-link {
  color: var(--dim);
  text-decoration: none;
  font-size: 0.85rem;
  font-family: ui-monospace, monospace;
}
.back-link:hover { color: var(--text); }

.app-title {
  font-size: 0.95rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-weight: 600;
}

main {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
}

/* ------------------------------------------------------------- menu ---- */

#menu {
  max-width: 740px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem 1.2rem 3rem;
  overflow-y: auto;
}

.intro {
  color: var(--dim);
  line-height: 1.65;
  font-size: 0.95rem;
  margin: 0 0 1.6rem;
}
.intro b { color: var(--text); }

.kbd {
  font-family: ui-monospace, monospace;
  font-size: 0.8em;
  background: var(--panel);
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 0.1em 0.45em;
  color: var(--text);
}

.diff-group { margin-bottom: 1.8rem; }

.diff-title {
  font-size: 0.78rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  margin: 0 0 0.7rem;
  font-weight: 600;
}
.diff-title.easy { color: var(--green); }
.diff-title.medium { color: var(--amber); }
.diff-title.hard { color: var(--red); }

.song-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  margin-bottom: 0.5rem;
  background: var(--panel);
}

.song-title { font-size: 0.98rem; }
.song-sub { font-size: 0.78rem; color: var(--dim); margin-top: 0.2rem; }
.song-actions { display: flex; gap: 0.45rem; flex-shrink: 0; }

.btn {
  font: inherit;
  font-size: 0.82rem;
  color: var(--text);
  background: rgba(63, 169, 255, 0.12);
  border: 1px solid rgba(63, 169, 255, 0.35);
  border-radius: 8px;
  padding: 0.42rem 0.85rem;
  cursor: pointer;
  transition: background 0.15s;
}
.btn:hover { background: rgba(63, 169, 255, 0.28); }
.btn.big {
  font-size: 0.95rem;
  padding: 0.6rem 1.6rem;
  background: rgba(63, 169, 255, 0.25);
}

/* ------------------------------------------------------------ stage ---- */

#stage {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
}

.stage-hud {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.5rem 0.9rem;
}

#exit-btn {
  font: inherit;
  color: var(--dim);
  background: none;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 0.15rem 0.55rem;
  cursor: pointer;
}
#exit-btn:hover { color: var(--text); }

#hud-title { font-size: 0.9rem; }

.mode-badge {
  font-family: ui-monospace, monospace;
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border-radius: 5px;
  padding: 0.15rem 0.5rem;
}
.mode-badge.play { background: rgba(63, 169, 255, 0.18); color: var(--blue); }
.mode-badge.practice { background: rgba(47, 230, 160, 0.15); color: var(--green); }

#hud-stats {
  margin-left: auto;
  font-family: ui-monospace, monospace;
  font-size: 0.82rem;
  color: var(--dim);
}

.progress {
  width: 130px;
  height: 4px;
  border-radius: 2px;
  background: var(--line);
  overflow: hidden;
}
#progress-fill { height: 100%; width: 0; background: var(--blue); }

.canvas-wrap {
  flex: 1;
  min-height: 0;
  position: relative;
}

#viz {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  touch-action: none;
}

/* ---------------------------------------------------------- overlay ---- */

.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(7, 11, 18, 0.72);
  backdrop-filter: blur(3px);
}

.overlay.bare {
  background: none;
  backdrop-filter: none;
  pointer-events: none;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.6rem 2rem;
  max-width: 560px;
  width: calc(100% - 2rem);
  max-height: calc(100% - 2rem);
  overflow-y: auto;
  text-align: center;
}

.panel-title { font-size: 1.25rem; font-weight: 600; }
.panel-sub { color: var(--dim); font-size: 0.85rem; margin-top: 0.3rem; }
.panel-hint { color: var(--dim); font-size: 0.88rem; line-height: 1.55; margin: 0.9rem 0; }
.panel-foot { color: var(--dim); font-size: 0.72rem; font-family: ui-monospace, monospace; margin-top: 1rem; }

.diff-chip {
  font-family: ui-monospace, monospace;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.diff-chip.easy { color: var(--green); }
.diff-chip.medium { color: var(--amber); }
.diff-chip.hard { color: var(--red); }

.speed-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: 0.82rem;
  color: var(--dim);
  margin: 0.8rem 0;
}

.pill {
  font: inherit;
  font-size: 0.8rem;
  color: var(--dim);
  background: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.25rem 0.8rem;
  cursor: pointer;
}
.pill.active { color: var(--text); border-color: var(--blue); background: rgba(63, 169, 255, 0.15); }

.label-toggle {
  display: block;
  font-size: 0.8rem;
  color: var(--dim);
  margin: 0 0 1.1rem;
  cursor: pointer;
}

.countdown {
  font-family: ui-monospace, monospace;
  font-size: 7rem;
  font-weight: 700;
  color: rgba(223, 230, 239, 0.85);
  text-shadow: 0 0 40px rgba(63, 169, 255, 0.5);
}

.btn-row { display: flex; gap: 0.6rem; justify-content: center; flex-wrap: wrap; margin-top: 0.4rem; }

/* ---------------------------------------------------------- results ---- */

.grade-letter {
  font-family: ui-monospace, monospace;
  font-size: 4.2rem;
  font-weight: 700;
  line-height: 1;
}
.grade-S { color: #7df0ff; text-shadow: 0 0 36px rgba(125, 240, 255, 0.6); }
.grade-A { color: var(--green); text-shadow: 0 0 30px rgba(47, 230, 160, 0.5); }
.grade-B { color: var(--blue); }
.grade-C { color: var(--amber); }
.grade-D { color: #ffaa64; }
.grade-F { color: var(--red); }

.grade-score { font-size: 1.3rem; margin-top: 0.2rem; }
.grade-score span { color: var(--dim); font-size: 0.85rem; }

.counts {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.4rem 1rem;
  font-family: ui-monospace, monospace;
  font-size: 0.78rem;
  margin: 0.9rem 0 1.1rem;
}
.c-perfect { color: #7df0ff; }
.c-good { color: var(--green); }
.c-ok { color: var(--amber); }
.c-miss { color: var(--red); }
.c-wrong { color: var(--dim); }

.tips {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
  text-align: left;
  margin-bottom: 1.2rem;
}
.tips-col h3 {
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  margin: 0 0 0.5rem;
}
.tips-col:first-child h3 { color: var(--green); }
.tips-col:last-child h3 { color: var(--amber); }
.tips-col ul { margin: 0; padding-left: 1.1rem; }
.tips-col li { font-size: 0.82rem; color: var(--dim); line-height: 1.5; margin-bottom: 0.45rem; }

@media (max-width: 560px) {
  .tips { grid-template-columns: 1fr; }
  .song-row { flex-direction: column; align-items: flex-start; }
  .song-actions { width: 100%; }
  .song-actions .btn { flex: 1; }
  .progress { display: none; }
}