:root {
  --primary: rgb(255, 125, 0);
  --primary-hover: rgb(255, 90, 0);
  --bg: #0f172a;
  --panel-bg: #1e293b;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --danger: #ef4444;
  --success: #22c55e;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  -webkit-tap-highlight-color: transparent;
}

body {
  background-color: var(--bg);
  color: var(--text);
  height: 100vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

canvas {
  display: block;
  background: radial-gradient(circle at center, #1e293b 0%, #0f172a 100%);
  flex-grow: 1;
  cursor: crosshair;
}

#settings-panel {
  position: absolute;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(
    135deg,
    rgba(30, 41, 59, 0.97),
    rgba(15, 23, 42, 0.97)
  );
  backdrop-filter: blur(12px);
  padding: 24px;
  border-radius: 16px;
  box-shadow:
    0 10px 40px rgba(0, 0, 0, 0.6),
    0 0 0 1px var(--border-glow);
  width: 90%;
  max-width: 640px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  z-index: 10;
  max-height: calc(100vh - 40px);
  overflow-y: auto;
}
#settings-panel::-webkit-scrollbar {
  width: 6px;
}
#settings-panel::-webkit-scrollbar-track {
  background: transparent;
}
#settings-panel::-webkit-scrollbar-thumb {
  background: rgba(99, 102, 241, 0.3);
  border-radius: 3px;
}

.hidden {
  opacity: 0;
  pointer-events: none;
}

h2 {
  font-size: 1.25rem;
  margin-bottom: 18px;
  text-align: center;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  padding-bottom: 12px;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  font-weight: 700;
  background: var(--primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.controls-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.control-group {
  padding: 16px;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.04);
  transition: border-color 0.2s;
}

.control-group.full-width {
  grid-column: span 2;
}

.split-row {
  grid-column: span 2;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.split-row .control-group {
  margin: 0;
}

label {
  display: block;
  margin-bottom: 8px;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.3px;
}

.planet-presets {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.planet-btn {
  flex: 1;
  min-width: 48px;
  padding: 6px 4px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.75rem;
  transition: all 0.2s;
  text-align: center;
  font-weight: 500;
}

.planet-btn:hover {
  background: rgba(255, 255, 255, 0.12);
  transform: translateY(-1px);
  border-color: var(--accent);
}

.planet-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  font-weight: bold;
  box-shadow: 0 0 12px var(--accent-glow);
}

/* Number inputs without spinners */
input[type='number'] {
  width: 100%;
  padding: 10px 12px;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 8px;
  color: white;
  font-size: 0.95rem;
  transition:
    border-color 0.2s,
    box-shadow 0.2s;
  outline: none;
  appearance: textfield;
}
input[type='number']:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}
input[type='number']::-webkit-outer-spin-button,
input[type='number']::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

input[type='range'] {
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 3px;
  outline: none;
  appearance: none;
  margin: 8px 0 4px;
}
input[type='range']::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  transition:
    transform 0.15s,
    box-shadow 0.15s;
  box-shadow: 0 0 6px var(--accent-glow);
}
input[type='range']::-webkit-slider-thumb:hover {
  transform: scale(1.15);
  box-shadow: 0 0 12px var(--accent-glow);
}
input[type='range']::-moz-range-thumb {
  width: 18px;
  height: 18px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  border: none;
}

.action-row {
  display: flex;
  gap: 10px;
  margin-top: 10px;
}

.btn {
  flex: 1;
  padding: 12px 10px;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.5px;
}

.btn-primary {
  background: var(--primary);
  color: white;
  box-shadow: 0 4px 15px var(--accent-glow);
}
.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px var(--accent-glow);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text);
  border: 1px solid rgba(255, 255, 255, 0.1);
}
.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: var(--accent);
}

.btn-danger {
  background: rgba(239, 68, 68, 0.15);
  color: var(--danger);
  border: 1px solid rgba(239, 68, 68, 0.3);
}
.btn-danger:hover {
  background: var(--danger);
  color: white;
}

.btn-small {
  padding: 6px 12px;
  font-size: 0.75rem;
  flex: 0 0 auto;
}

#sim-controls {
  position: absolute;
  top: 50%;
  left: 10px;
  transform: translateY(-50%);
  background: rgba(15, 23, 42, 0.92);
  backdrop-filter: blur(8px);
  padding: 14px 10px;
  border-radius: 14px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  z-index: 20;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.5);
}

.sim-stat {
  font-family: monospace;
  font-size: 0.9rem;
  color: var(--text-muted);
  white-space: nowrap;
}
.sim-stat span {
  color: var(--text);
  font-weight: bold;
}

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(6px);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: all;
}

.modal-content {
  background: linear-gradient(135deg, var(--panel-bg), #0f172a);
  padding: 28px;
  border-radius: 16px;
  width: 90%;
  max-width: 440px;
  box-shadow: 0 25px 60px rgba(0, 0, 0, 0.6);
  border: 1px solid var(--border-glow);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.modal-header h3 {
  font-size: 1.15rem;
  font-weight: 700;
  background: var(--primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.modal-body {
  margin-bottom: 20px;
}

.modal-body label {
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.modal-body input[type='text'] {
  width: 100%;
  padding: 12px 14px;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 8px;
  color: white;
  font-size: 1rem;
  outline: none;
  transition:
    border-color 0.2s,
    box-shadow 0.2s;
}
.modal-body input[type='text']:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.modal-actions {
  display: flex;
  gap: 10px;
}
.modal-actions .btn {
  flex: 1;
}

.save-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  max-height: 400px;
  overflow-y: auto;
}

.save-item {
  background: rgba(255, 255, 255, 0.04);
  padding: 14px 16px;
  border-radius: 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  transition: all 0.2s;
  border: 1px solid transparent;
}

.save-item:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--accent);
  box-shadow: 0 0 15px var(--accent-glow);
  transform: translateX(2px);
}

.save-info h4 {
  color: var(--text);
  margin-bottom: 3px;
  font-size: 0.95rem;
}
.save-info p {
  color: var(--text-muted);
  font-size: 0.75rem;
  line-height: 1.4;
}

.save-actions {
  display: flex;
  gap: 6px;
}
.save-actions button {
  margin-left: 0;
  padding: 6px 14px;
  font-size: 0.75rem;
  border-radius: 6px;
}

.save-list::-webkit-scrollbar {
  width: 6px;
}
.save-list::-webkit-scrollbar-track {
  background: transparent;
}
.save-list::-webkit-scrollbar-thumb {
  background: rgba(99, 102, 241, 0.3);
  border-radius: 3px;
}

/* ===== Delete confirmation modal ===== */
.modal-confirm {
  max-width: 360px;
  text-align: center;
  padding: 30px 26px;
}

.confirm-icon {
  font-size: 2.4rem;
  line-height: 1;
  margin-bottom: 14px;
  animation: confirm-pop 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.modal-confirm h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text);
  background: none;
  -webkit-text-fill-color: var(--text);
  background-clip: unset;
}

.modal-confirm p {
  color: var(--text-muted);
  font-size: 0.92rem;
  line-height: 1.55;
  margin-bottom: 24px;
}

.confirm-actions .btn {
  padding: 12px 0;
  font-size: 0.85rem;
  border-radius: 10px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.confirm-actions .btn-secondary {
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.confirm-actions .btn-danger {
  background: var(--danger);
  color: #fff;
  border: none;
  box-shadow: 0 6px 18px rgba(239, 68, 68, 0.35);
}

.confirm-actions .btn-danger:hover {
  background: rgb(220, 38, 38);
  transform: translateY(-1px);
  box-shadow: 0 8px 24px rgba(239, 68, 68, 0.5);
}

@keyframes confirm-pop {
  0% {
    transform: scale(0.5);
    opacity: 0;
  }
  70% {
    transform: scale(1.15);
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}

/* Responsive: small screens — stack save items so buttons never overflow */
@media (max-width: 480px) {
  .save-list {
    max-height: 55vh;
  }
  .save-item {
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
  }
  .save-item:hover {
    transform: none;
  }
  .save-actions {
    justify-content: flex-end;
    flex-wrap: wrap;
  }
  .save-actions button {
    flex: 1;
    min-width: 0;
    white-space: nowrap;
    padding: 8px 10px;
  }
  .modal-confirm {
    padding: 24px 18px;
  }
}

.btn-donate-glow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--primary);
  color: white;
  padding: 8px 20px;
  border-radius: 25px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.85rem;
  transition: all 0.2s;
  box-shadow: 0 0 20px var(--accent-glow);
  cursor: pointer;
}
.btn-donate-glow:hover {
  transform: translateY(-1px);
  box-shadow: 0 0 30px var(--accent-glow);
}
.btn-icon {
  font-size: 1rem;
}

/* Responsive: viewport width < 600px — shrink sim-controls */
@media (max-width: 600px) {
  #sim-controls {
    left: 6px;
    padding: 10px 6px;
    gap: 5px;
    border-radius: 10px;
    max-width: 40vw;
  }
  #sim-controls .sim-stat {
    font-size: 0.7rem;
  }
  #sim-controls #simBallSpeedLabel,
  #sim-controls #simCollisionTimeLabel {
    font-size: 0.6rem;
  }
  #sim-controls input[type='range'] {
    width: 60px;
  }
  #sim-controls .btn-small {
    padding: 3px 6px;
    font-size: 0.6rem;
  }
}

/* Responsive: viewport width < 350px — even smaller */
@media (max-width: 350px) {
  #sim-controls {
    left: 4px;
    padding: 6px 4px;
    gap: 3px;
    border-radius: 8px;
    max-width: 50vw;
  }
  #sim-controls .sim-stat {
    font-size: 0.55rem;
  }
  #sim-controls #timeScaleSlider {
    width: 30px !important;
    height: 3px;
  }
  #sim-controls #btnResetSpeed {
    padding: 2px 3px !important;
    font-size: 0.45rem !important;
  }
  #sim-controls .btn-small {
    padding: 2px 4px;
    font-size: 0.5rem;
  }
  #sim-controls .btn-small#btnPauseSim {
    min-width: 40px;
  }
}

/* Mobile responsive - small screens (width or height) — keep original at bottom */
@media (max-width: 350px), (max-height: 350px) {
  html,
  body {
    font-size: 11px;
  }

  #settings-panel {
    top: 5px;
    padding: 10px;
    width: 96%;
    max-width: 100%;
    border-radius: 10px;
  }

  #settings-panel h2 {
    font-size: 1rem;
    margin-bottom: 10px;
    padding-bottom: 8px;
  }

  .controls-grid {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .control-group {
    padding: 10px;
  }

  .control-group.full-width,
  .split-row {
    grid-column: span 1;
  }

  .split-row {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .planet-presets {
    gap: 4px;
    margin-top: 6px;
  }

  .planet-btn {
    min-width: 36px;
    padding: 4px 2px;
    font-size: 0.65rem;
  }

  input[type='number'] {
    padding: 6px 8px;
    font-size: 0.85rem;
  }

  input[type='range'] {
    height: 4px;
    margin: 4px 0 2px;
  }
  input[type='range']::-webkit-slider-thumb {
    width: 14px;
    height: 14px;
  }

  .action-row {
    gap: 6px;
    margin-top: 6px;
  }

  .btn {
    padding: 8px 6px;
    font-size: 0.7rem;
  }

  #sim-controls {
    left: 5px;
    padding: 8px 6px;
    gap: 5px;
  }

  .sim-stat {
    font-size: 0.75rem;
  }

  .modal-content {
    padding: 16px;
    max-width: 95%;
  }

  .save-item {
    padding: 10px 12px;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .save-info h4 {
    font-size: 0.85rem;
  }

  .save-info p {
    font-size: 0.7rem;
  }

  .save-actions {
    align-self: flex-end;
  }
}

/* ===== Download for Android button ===== */
.download-android-btn {
  box-shadow: rgba(61, 220, 132, 0.3) 0px 4px 12px;
  color: rgb(255, 255, 255);
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  text-align: center;
  width: 60%;
  background: linear-gradient(135deg, rgb(61, 220, 132), rgb(46, 125, 50));
  border-width: medium;
  border-style: none;
  border-color: currentcolor;
  border-image: none;
  border-radius: 12px;
  padding: 14px 20px;
  text-decoration: none;
  transition: 0.3s;
  display: inline-block;
}

.download-android-btn:hover {
  transform: translateY(-2px);
  box-shadow: rgba(61, 220, 132, 0.5) 0px 8px 20px;
  filter: brightness(1.05);
}

.download-android-btn:active {
  transform: translateY(0);
  box-shadow: rgba(61, 220, 132, 0.3) 0px 4px 12px;
}


/* ===== Tech support button ===== */
.support-btn {
  box-shadow: rgba(214, 48, 49, 0.3) 0px 4px 15px;
  color: rgb(255, 255, 255);
  cursor: pointer;
  display: inline-block;
  font-size: 1rem;
  font-weight: 600;
  background: red;
  border-width: medium;
  border-style: none;
  border-color: currentcolor;
  border-image: none;
  border-radius: 50px;
  padding: 12px 28px;
  text-decoration: none;
  transition: 0.3s;
}

.support-btn:hover {
  transform: translateY(-2px);
  box-shadow: rgba(214, 48, 49, 0.5) 0px 6px 18px;
  filter: brightness(1.1);
}

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