* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --bg: #0B0B0B;
  --bg-card: #111111;
  --bg-code: #1a1a1a;
  --green: #33FF33;
  --green-dim: #1a8a1a;
  --green-dark: #0d3d0d;
  --amber: #FFB000;
  --amber-dim: #8a6000;
  --text: #C0C0C0;
  --text-dim: #707070;
  --blue: #00AAFF;
  --purple: #AA66FF;
  --cyan: #00FFCC;
  --red: #FF4444;
  --border-green: #1a3a1a;
  --border-amber: #3a2a00;
  --font-mono: 'IBM Plex Mono', 'Courier New', monospace;
  --font-display: 'Share Tech Mono', monospace;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-mono);
  overflow-x: hidden;
}

body::after {
  content: '';
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 2px,
    rgba(0,0,0,0.06) 2px,
    rgba(0,0,0,0.06) 4px
  );
  pointer-events: none;
  z-index: 9999;
}

.glow-green {
  color: var(--green);
  text-shadow: 0 0 8px rgba(51,255,51,0.6), 0 0 20px rgba(51,255,51,0.3);
}
.glow-amber {
  color: var(--amber);
  text-shadow: 0 0 8px rgba(255,176,0,0.5), 0 0 16px rgba(255,176,0,0.2);
}
.glow-blue {
  color: var(--blue);
  text-shadow: 0 0 6px rgba(0,170,255,0.5);
}
.glow-purple {
  color: var(--purple);
  text-shadow: 0 0 6px rgba(170,102,255,0.5);
}
.glow-cyan {
  color: var(--cyan);
  text-shadow: 0 0 6px rgba(0,255,204,0.5);
}
.glow-red {
  color: var(--red);
  text-shadow: 0 0 6px rgba(255,68,68,0.5);
}

@keyframes blink {
  0%, 50% { opacity: 1; }
  51%, 100% { opacity: 0; }
}
.cursor-blink { animation: blink 1s infinite; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}
.fade-in { animation: fadeIn 0.3s ease-out; }

.tab-btn {
  background: #1a1a1a;
  border: 1px solid var(--border-green);
  color: var(--text-dim);
  padding: 10px 24px;
  font-family: var(--font-mono);
  font-size: 14px;
  cursor: pointer;
  transition: all 0.3s;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.tab-btn:hover { border-color: var(--green-dim); color: var(--text); }
.tab-btn.active {
  background: var(--green-dark);
  border-color: var(--green);
  color: var(--green);
  text-shadow: 0 0 8px rgba(51,255,51,0.4);
}

.section-header {
  cursor: pointer;
  user-select: none;
  transition: all 0.2s;
}
.section-header:hover { background: rgba(51,255,51,0.05); }

.code-block {
  background: var(--bg-code);
  border: 1px solid var(--border-green);
  border-radius: 4px;
  padding: 16px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.6;
  color: var(--green);
}

.hex-byte {
  cursor: pointer;
  padding: 1px 3px;
  border-radius: 2px;
  transition: all 0.15s;
}
.hex-byte:hover {
  background: var(--green-dark);
  color: var(--green);
  text-shadow: 0 0 6px rgba(51,255,51,0.5);
}

.opcode-table { width: 100%; border-collapse: collapse; }
.opcode-table th {
  background: #1a1a1a;
  color: var(--amber);
  padding: 8px 12px;
  text-align: left;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 1px;
  border-bottom: 1px solid var(--border-amber);
  position: sticky;
  top: 0;
  z-index: 2;
}
.opcode-table td {
  padding: 6px 12px;
  font-size: 13px;
  border-bottom: 1px solid #1a1a1a;
}
.opcode-table tr:hover td { background: rgba(51,255,51,0.05); }
.opcode-table tr.expanded-row td { background: rgba(255,176,0,0.05); border-bottom: none; }
.opcode-table tr.detail-row td { background: rgba(255,176,0,0.03); }

.info-card {
  background: var(--bg-code);
  border: 1px solid var(--border-green);
  border-radius: 6px;
  padding: 16px;
}

.warning-card {
  background: rgba(255,176,0,0.05);
  border: 1px solid var(--border-amber);
  border-left: 3px solid var(--amber);
  border-radius: 4px;
  padding: 12px 16px;
}

.chip8-display {
  background: #000;
  border: 2px solid var(--green-dim);
  image-rendering: pixelated;
}

.apple1-terminal {
  background: #000;
  border: 2px solid var(--green-dim);
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--green);
  padding: 12px;
  min-height: 300px;
  overflow-y: auto;
  white-space: pre-wrap;
  word-break: break-all;
  cursor: text;
}

::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: #0a0a0a; }
::-webkit-scrollbar-thumb { background: #2a2a2a; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #3a3a3a; }

.mem-region {
  border: 1px solid var(--border-green);
  padding: 6px 10px;
  font-size: 12px;
  transition: all 0.2s;
}
.mem-region:hover {
  border-color: var(--green);
  background: rgba(51,255,51,0.05);
}

.filter-input {
  background: var(--bg-code);
  border: 1px solid var(--border-green);
  color: var(--green);
  padding: 8px 14px;
  font-family: var(--font-mono);
  font-size: 13px;
  outline: none;
  width: 100%;
  border-radius: 4px;
}
.filter-input:focus {
  border-color: var(--green);
  box-shadow: 0 0 8px rgba(51,255,51,0.2);
}
.filter-input::placeholder { color: var(--text-dim); }

.retro-btn {
  background: var(--bg-code);
  border: 1px solid var(--green-dim);
  color: var(--green);
  padding: 8px 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: all 0.2s;
}
.retro-btn:hover {
  background: var(--green-dark);
  border-color: var(--green);
  text-shadow: 0 0 6px rgba(51,255,51,0.4);
}
.retro-btn:active { transform: scale(0.97); }
.retro-btn:disabled { opacity: 0.4; cursor: not-allowed; }
.retro-btn.blue { border-color: rgba(0,170,255,0.5); color: var(--blue); }
.retro-btn.blue:hover { background: rgba(0,170,255,0.1); border-color: var(--blue); }
.retro-btn.amber { border-color: var(--amber-dim); color: var(--amber); }
.retro-btn.amber:hover { background: rgba(255,176,0,0.1); border-color: var(--amber); }
.retro-btn.purple { border-color: rgba(170,102,255,0.5); color: var(--purple); }
.retro-btn.purple:hover { background: rgba(170,102,255,0.1); border-color: var(--purple); }
.retro-btn.small { padding: 4px 10px; font-size: 10px; }

.tooltip {
  position: absolute;
  background: #1a1a1a;
  border: 1px solid var(--green);
  color: var(--green);
  padding: 8px 12px;
  font-size: 12px;
  border-radius: 4px;
  z-index: 1000;
  pointer-events: none;
  white-space: nowrap;
  box-shadow: 0 0 12px rgba(51,255,51,0.2);
}

.keypad-key {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-code);
  border: 1px solid var(--border-green);
  color: var(--amber);
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 600;
  border-radius: 4px;
  transition: all 0.15s;
}
.keypad-key:hover, .keypad-key.active {
  background: var(--green-dark);
  border-color: var(--green);
  color: var(--green);
}

.hr-glow {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--green-dim), var(--green), var(--green-dim), transparent);
  border: none;
  margin: 12px 0;
}

.reg-val {
  font-family: var(--font-mono);
  color: var(--green);
  background: #0a0a0a;
  padding: 2px 6px;
  border-radius: 2px;
  font-size: 12px;
}

.timeline-item {
  position: relative;
  padding-left: 24px;
  padding-bottom: 16px;
  border-left: 2px solid var(--border-green);
}
.timeline-item:last-child { border-left-color: transparent; }
.timeline-item::before {
  content: '';
  position: absolute;
  left: -5px; top: 4px;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 8px rgba(51,255,51,0.6);
}

.sprite-pixel {
  border: 1px solid #222;
  cursor: pointer;
  transition: background 0.1s;
}
.sprite-pixel:hover { border-color: var(--green-dim); }
.sprite-pixel.on { background: var(--green) !important; box-shadow: 0 0 4px rgba(51,255,51,0.4); }
.sprite-pixel.off { background: #111 !important; }

.quirk-badge {
  display: inline-block;
  padding: 1px 6px;
  border-radius: 3px;
  font-size: 10px;
  font-weight: 600;
  background: rgba(255,176,0,0.15);
  color: var(--amber);
  border: 1px solid var(--amber-dim);
}

.chip8-sub-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-bottom: 16px;
}
.chip8-sub-nav button {
  background: #111;
  border: 1px solid #222;
  color: var(--text-dim);
  padding: 5px 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  cursor: pointer;
  transition: all 0.2s;
  border-radius: 3px;
}
.chip8-sub-nav button:hover { border-color: var(--green-dim); color: var(--text); }
.chip8-sub-nav button.active {
  background: var(--green-dark);
  border-color: var(--green-dim);
  color: var(--green);
}

@media (max-width: 768px) {
  .tab-btn { padding: 8px 14px; font-size: 11px; letter-spacing: 0.5px; }
  .code-block { font-size: 11px; padding: 10px; }
  .apple1-terminal { font-size: 12px; min-height: 220px; }
  .chip8-sub-nav button { padding: 4px 8px; font-size: 10px; }
}