/* ── RESET & ROOT ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0d0d0f;
  --surface: #16161a;
  --surface2: #1e1e24;
  --border: #2a2a35;
  --border-bright: #3d3d4e;
  --text: #e8e8f0;
  --text-muted: #7070a0;
  --text-dim: #404060;
  --accent: #c8a96e;
  --accent-glow: rgba(200, 169, 110, 0.15);
  --accent2: #7c9ed9;
  --given: #e8e8f0;
  --solved: #c8a96e;
  --error: #e06c75;
  --error-bg: rgba(224, 108, 117, 0.08);
  --highlight-row: rgba(200, 169, 110, 0.05);
  --highlight-box: rgba(124, 158, 217, 0.06);
  --cell-size: 54px;
}

html { height: 100%; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'DM Sans', sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 40px 20px 60px;
  position: relative;
  overflow-x: hidden;
}

/* Background texture */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 20% 10%, rgba(200,169,110,0.04) 0%, transparent 60%),
    radial-gradient(ellipse 60% 60% at 80% 80%, rgba(124,158,217,0.04) 0%, transparent 60%);
  pointer-events: none;
  z-index: 0;
}

body::after {
  content: '';
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg width='40' height='40' xmlns='http://www.w3.org/2000/svg'%3E%3Ccircle cx='1' cy='1' r='0.5' fill='%23ffffff' opacity='0.015'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 0;
}

/* ── HEADER ── */
header {
  position: relative;
  z-index: 1;
  text-align: center;
  margin-bottom: 36px;
  animation: fadeDown 0.7s ease both;
}

.logo-label {
  font-family: 'DM Mono', monospace;
  font-size: 11px;
  letter-spacing: 0.35em;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 8px;
}

h1 {
  font-family: 'Playfair Display', serif;
  font-size: clamp(42px, 8vw, 72px);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1;
  color: var(--text);
}

h1 span {
  color: var(--accent);
}

.tagline {
  font-size: 13px;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  margin-top: 10px;
  font-weight: 300;
}

/* ── STATUS BAR ── */
.status-bar {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 24px;
  margin-bottom: 24px;
  animation: fadeDown 0.7s 0.1s ease both;
}

.stat-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 8px 16px;
  font-family: 'DM Mono', monospace;
  font-size: 13px;
}

.stat-pill .label {
  color: var(--text-muted);
  font-size: 10px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.stat-pill .value {
  color: var(--text);
  font-weight: 500;
  min-width: 48px;
  text-align: center;
}

#timer-val { color: var(--accent); }
#errors-val { color: var(--error); }

/* ── DIFFICULTY TABS ── */
.difficulty-tabs {
  position: relative;
  z-index: 1;
  display: flex;
  gap: 4px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 4px;
  margin-bottom: 28px;
  animation: fadeDown 0.7s 0.15s ease both;
}

.diff-tab {
  padding: 8px 20px;
  border-radius: 8px;
  border: none;
  background: transparent;
  color: var(--text-muted);
  font-family: 'DM Sans', sans-serif;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  letter-spacing: 0.02em;
}

.diff-tab:hover { color: var(--text); }

.diff-tab.active {
  background: var(--surface2);
  color: var(--accent);
  border: 1px solid var(--border-bright);
}

/* ── GRID WRAPPER ── */
.grid-wrapper {
  position: relative;
  z-index: 1;
  animation: fadeUp 0.7s 0.2s ease both;
}

/* ── SUDOKU GRID ── */
#grid {
  display: grid;
  grid-template-columns: repeat(9, var(--cell-size));
  grid-template-rows: repeat(9, var(--cell-size));
  gap: 0;
  border: 2.5px solid var(--accent);
  box-shadow:
    0 0 0 1px var(--bg),
    0 0 40px rgba(200,169,110,0.08),
    0 20px 60px rgba(0,0,0,0.5);
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}

.cell {
  width: var(--cell-size);
  height: var(--cell-size);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  background: var(--surface);
  transition: background 0.15s;
  position: relative;
  cursor: pointer;
}

/* Right thick borders for 3×3 box columns */
.cell[data-col="2"],
.cell[data-col="5"] {
  border-right: 2px solid var(--border-bright);
}

/* Bottom thick borders for 3×3 box rows */
.cell[data-row="2"],
.cell[data-row="5"] {
  border-bottom: 2px solid var(--border-bright);
}

.cell.highlighted-row { background: var(--highlight-row); }
.cell.highlighted-box { background: var(--highlight-box); }
.cell.selected        { background: rgba(200,169,110,0.1) !important; }
.cell.same-number     { background: rgba(200,169,110,0.07) !important; }
.cell.error           { background: var(--error-bg) !important; }

.cell input {
  width: 100%;
  height: 100%;
  background: transparent;
  border: none;
  outline: none;
  text-align: center;
  font-family: 'Playfair Display', serif;
  font-size: 22px;
  font-weight: 700;
  color: var(--accent2);
  caret-color: transparent;
  cursor: pointer;
  -moz-appearance: textfield;
}

.cell input::-webkit-outer-spin-button,
.cell input::-webkit-inner-spin-button { -webkit-appearance: none; }

.cell.given input {
  color: var(--given);
  pointer-events: none;
}

.cell.solved-anim input {
  color: var(--solved);
  animation: popIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

.cell.error input { color: var(--error); }

/* ── NOTES MODE ── */
.cell.notes-mode .notes-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  width: 100%;
  height: 100%;
  padding: 3px;
}

.note-digit {
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'DM Mono', monospace;
  font-size: 8px;
  color: var(--text-muted);
  line-height: 1;
}

/* ── NUMBER PAD ── */
.numpad {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 6px;
  margin-top: 20px;
  width: calc(var(--cell-size) * 9);
  animation: fadeUp 0.7s 0.25s ease both;
  position: relative;
  z-index: 1;
}

.num-btn {
  height: 44px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-family: 'Playfair Display', serif;
  font-size: 20px;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.num-btn:hover {
  background: var(--surface2);
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(200,169,110,0.15);
}

.num-btn:active { transform: translateY(0); }

.num-btn.exhausted {
  opacity: 0.25;
  pointer-events: none;
}

/* ── ACTION BUTTONS ── */
.actions {
  display: flex;
  gap: 10px;
  margin-top: 20px;
  flex-wrap: wrap;
  justify-content: center;
  position: relative;
  z-index: 1;
  animation: fadeUp 0.7s 0.3s ease both;
}

.btn {
  padding: 12px 24px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font-family: 'DM Sans', sans-serif;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  letter-spacing: 0.03em;
  display: flex;
  align-items: center;
  gap: 6px;
}

.btn:hover {
  background: var(--surface2);
  border-color: var(--border-bright);
  transform: translateY(-1px);
}

.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #0d0d0f;
  font-weight: 600;
  box-shadow: 0 4px 20px rgba(200,169,110,0.25);
}

.btn.primary:hover {
  background: #d9bc88;
  box-shadow: 0 6px 28px rgba(200,169,110,0.35);
  transform: translateY(-2px);
}

.btn.danger { color: var(--error); }
.btn.danger:hover { border-color: var(--error); }

.btn.notes-active {
  background: rgba(124,158,217,0.15);
  border-color: var(--accent2);
  color: var(--accent2);
}

/* ── TOAST ── */
#toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--surface2);
  border: 1px solid var(--border-bright);
  border-radius: 12px;
  padding: 14px 28px;
  font-size: 14px;
  color: var(--text);
  box-shadow: 0 8px 32px rgba(0,0,0,0.4);
  transition: transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
  z-index: 100;
  white-space: nowrap;
}

#toast.show          { transform: translateX(-50%) translateY(0); }
#toast.success       { border-color: var(--accent); color: var(--accent); }
#toast.error-toast   { border-color: var(--error);  color: var(--error); }

/* ── WIN OVERLAY ── */
#win-overlay {
  position: fixed;
  inset: 0;
  background: rgba(13,13,15,0.92);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.5s;
  backdrop-filter: blur(8px);
}

#win-overlay.show { opacity: 1; pointer-events: all; }

.win-card {
  background: var(--surface);
  border: 1px solid var(--border-bright);
  border-radius: 24px;
  padding: 56px 64px;
  text-align: center;
  box-shadow: 0 40px 80px rgba(0,0,0,0.6), 0 0 0 1px var(--accent) inset;
  transform: scale(0.9);
  transition: transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

#win-overlay.show .win-card { transform: scale(1); }

.win-emoji  { font-size: 64px; margin-bottom: 16px; }

.win-title {
  font-family: 'Playfair Display', serif;
  font-size: 40px;
  font-weight: 900;
  color: var(--accent);
  margin-bottom: 8px;
}

.win-subtitle { color: var(--text-muted); font-size: 15px; margin-bottom: 32px; }

.win-stats {
  display: flex;
  gap: 32px;
  justify-content: center;
  margin-bottom: 32px;
}

.win-stat { text-align: center; }

.win-stat .ws-val {
  font-family: 'Playfair Display', serif;
  font-size: 32px;
  font-weight: 700;
  color: var(--text);
}

.win-stat .ws-label {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.15em;
}

/* ── ANIMATIONS ── */
@keyframes popIn {
  0%   { transform: scale(0.5); opacity: 0; }
  100% { transform: scale(1);   opacity: 1; }
}

@keyframes fadeDown {
  from { opacity: 0; transform: translateY(-16px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── SOLVING PULSE ── */
#grid.solving { animation: solvePulse 0.6s ease infinite alternate; }

@keyframes solvePulse {
  from { box-shadow: 0 0 0 1px var(--bg), 0 0 40px rgba(200,169,110,0.08), 0 20px 60px rgba(0,0,0,0.5); }
  to   { box-shadow: 0 0 0 1px var(--bg), 0 0 60px rgba(200,169,110,0.25), 0 20px 60px rgba(0,0,0,0.5); }
}

/* ── RESPONSIVE ── */
@media (max-width: 540px) {
  :root { --cell-size: 38px; }
  h1 { font-size: 36px; }
  .cell input { font-size: 17px; }
  .status-bar { gap: 10px; }
  .stat-pill  { padding: 6px 12px; }
  .actions    { gap: 6px; }
  .btn        { padding: 10px 16px; font-size: 12px; }
}