:root {
  --bg: #0b0e1a;
  --panel: #121629;
  --panel-2: #181d35;
  --overlay: rgba(18, 22, 41, 0.88);
  --text: #e6e9f5;
  --muted: #8a93b8;
  --accent: #6ea8fe;
  --border: #232945;
  --error: #ff6b7a;
  --success: #7ee787;
  --row-sel: #1f2648;
}

body.light {
  --bg: #f5f6fa;
  --panel: #ffffff;
  --panel-2: #f1f3fa;
  --overlay: rgba(255, 255, 255, 0.9);
  --text: #1d2140;
  --muted: #6a7090;
  --accent: #3870e0;
  --border: #dfe3ee;
  --error: #c2334a;
  --success: #1a7a2e;
  --row-sel: #e9eefc;
}

* { box-sizing: border-box; }

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

header {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 10px 20px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  height: 52px;
}

header h1 {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.2px;
}
header h1 .accent { color: var(--accent); }

header .spacer { flex: 1; }

header button, header select {
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 12px;
  font-size: 12px;
  cursor: pointer;
  font-family: inherit;
}

header button:hover { border-color: var(--accent); }

main {
  display: grid;
  grid-template-columns: 340px 1fr 440px;
  height: calc(100vh - 52px);
}

@media (max-width: 1100px) {
  main { grid-template-columns: 280px 1fr 360px; }
}

@media (max-width: 820px) {
  main { grid-template-columns: 1fr; grid-template-rows: auto 300px auto; overflow-y: auto; height: auto; }
}

.panel {
  background: var(--panel);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.panel:last-child { border-right: none; border-left: 1px solid var(--border); }

.panel-header {
  padding: 10px 16px;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 10px;
}

.panel-header .spacer { flex: 1; }

.panel-body {
  flex: 1;
  overflow-y: scroll;
  scrollbar-gutter: stable;
  padding: 12px;
}
/* Hide the scrollbar track visually while still reserving its gutter. */
.panel-body::-webkit-scrollbar {
  width: 10px;
}
.panel-body::-webkit-scrollbar-track { background: transparent; }
.panel-body::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 5px;
  border: 2px solid var(--panel);
}
.panel-body::-webkit-scrollbar-thumb:hover { background: var(--muted); }
.panel-body { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }

/* Calculator rows */
.row {
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  margin-bottom: 8px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  grid-template-rows: auto auto;
  gap: 8px;
  align-items: center;
  cursor: text;
  transition: border-color 0.12s;
}
.row:hover { border-color: var(--accent); }
.row.selected { background: var(--row-sel); border-color: var(--accent); }

.chip {
  width: 18px; height: 18px;
  border-radius: 50%;
  border: 2px solid;
  cursor: pointer;
  padding: 0;
}

.color-popover {
  position: fixed;
  z-index: 100;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.35);
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.swatches {
  display: grid;
  grid-template-columns: repeat(7, 22px);
  gap: 6px;
}
.swatch {
  width: 22px; height: 22px;
  border-radius: 50%;
  border: 2px solid transparent;
  cursor: pointer;
  padding: 0;
  transition: transform 0.08s;
}
.swatch:hover { transform: scale(1.12); }
.swatch.active { border-color: var(--text); box-shadow: 0 0 0 2px var(--panel); }
.chip-hidden {
  opacity: 0.4;
}

.popover-label {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-top: 4px;
}

.popover-slider-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.popover-slider {
  flex: 1;
  accent-color: var(--accent);
  height: 4px;
  cursor: pointer;
}

.popover-slider-val {
  font-size: 11px;
  color: var(--text);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  min-width: 32px;
  text-align: right;
}

.popover-style-row {
  display: flex;
  gap: 4px;
}

.popover-style-btn {
  flex: 1;
  background: var(--panel-2);
  color: var(--muted);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 5px 8px;
  font-size: 11px;
  cursor: pointer;
  transition: border-color 0.08s, color 0.08s;
}
.popover-style-btn:hover { border-color: var(--accent); color: var(--accent); }
.popover-style-btn.active { border-color: var(--accent); color: var(--accent); background: rgba(110, 168, 254, 0.1); }

.row-input {
  background: transparent;
  border: none;
  outline: none;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 14px;
  color: var(--text);
  width: 100%;
  padding: 2px 0;
}
.row-input:disabled,
.row-input[readonly] { color: var(--muted); font-style: italic; }

.del {
  background: transparent;
  border: none;
  color: var(--muted);
  font-size: 18px;
  width: 22px; height: 22px;
  border-radius: 4px;
  cursor: pointer;
}
.del:hover { color: var(--error); background: rgba(255, 107, 122, 0.08); }

.row-preview {
  grid-column: 2 / 4;
  color: var(--text);
  min-height: 20px;
  display: flex;
  align-items: flex-end;
  gap: 8px;
  padding: 2px 0;
  font-size: 16px;
}
.row-preview:empty { display: none; }
.row-preview .preview-math {
  min-width: 0;
  flex: 1;
  overflow-x: auto;
  overflow-y: hidden;
}
.row-preview .preview-math mjx-container { text-align: left !important; }
.preview-tokens {
  color: var(--muted);
  font-size: 11px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  white-space: nowrap;
  flex-shrink: 0;
  align-self: flex-end;
  line-height: 1;
}

.row-badge {
  grid-column: 2 / 4;
  font-size: 11px;
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  min-height: 14px;
  display: flex;
  align-items: baseline;
  gap: 6px;
}
.row-badge.error { color: var(--error); }
.row-badge.value .badge-main { color: var(--success); font-size: 12px; }
.row-badge.eml-mode .badge-main { color: var(--accent); font-style: italic; }
.badge-main { flex: 1; min-width: 0; }
.badge-tokens { color: var(--muted); font-size: 11px; flex-shrink: 0; white-space: nowrap; }

#add-row {
  width: 100%;
  background: transparent;
  border: 1px dashed var(--border);
  border-radius: 10px;
  color: var(--muted);
  padding: 10px;
  font-size: 13px;
  cursor: pointer;
}
#add-row:hover { border-color: var(--accent); color: var(--accent); }

.row-input {
  font-size: 15px;
  padding: 6px 4px;
}
.row-input::placeholder { color: var(--muted); opacity: 0.7; }

.left-body {
  display: flex;
  flex-direction: column;
  padding: 0;
  overflow: hidden;
}
.rows-scroll {
  flex: 1;
  overflow-y: scroll;
  scrollbar-gutter: stable;
  padding: 12px;
  min-height: 0;
}
.rows-scroll::-webkit-scrollbar { width: 10px; }
.rows-scroll::-webkit-scrollbar-track { background: transparent; }
.rows-scroll::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 5px;
  border: 2px solid var(--panel);
}
.rows-scroll::-webkit-scrollbar-thumb:hover { background: var(--muted); }
.rows-scroll { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }

.keypad {
  padding: 12px;
  border-top: 1px solid var(--border);
  background: var(--panel);
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex-shrink: 0;
}
.keypad-row {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 6px;
}
.keypad button {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 8px 0;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 13px;
  cursor: pointer;
  transition: background 0.08s, border-color 0.08s;
}
.keypad button:hover { background: var(--row-sel); border-color: var(--accent); color: var(--accent); }
.keypad button.small { font-size: 14px; }
.keypad button.back { color: var(--error); }

/* Graph panel */
#graph-wrap {
  position: relative;
  flex: 1;
  background: var(--bg);
}
#canvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: grab;
  touch-action: none;
}
#canvas:active { cursor: grabbing; }

.graph-credit {
  position: absolute;
  right: 16px;
  bottom: 16px;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--overlay);
  color: var(--muted);
  font-size: 11px;
  line-height: 1;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.18);
  backdrop-filter: blur(10px);
  pointer-events: none;
}

.graph-credit-copy {
  white-space: nowrap;
}

.graph-credit a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  transition: color 0.12s ease;
  pointer-events: auto;
}

.graph-credit a:hover {
  color: var(--accent);
}

.graph-credit svg {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
}

/* EML panel */
#eml-out {
  flex: 1;
  width: 100%;
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12.5px;
  line-height: 1.55;
  resize: none;
  outline: none;
  word-break: break-all;
  white-space: pre-wrap;
  min-height: 240px;
}
#eml-out:focus { border-color: var(--accent); }

#eml-stats {
  font-size: 11px;
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  margin-top: 8px;
}

#row-value {
  margin-top: 10px;
  padding: 10px 12px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 13px;
  color: var(--success);
  min-height: 20px;
  word-break: break-all;
}
#row-value:empty { display: none; }

.panel.right .panel-body {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.eml-controls {
  display: flex;
  gap: 8px;
  align-items: center;
}
.eml-controls button, .eml-controls select {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 5px 10px;
  border-radius: 6px;
  font-size: 11.5px;
  cursor: pointer;
  font-family: inherit;
}
.eml-controls button:hover { border-color: var(--accent); }

.hint {
  font-size: 11px;
  color: var(--muted);
  padding: 8px 12px;
  border-left: 2px solid var(--accent);
  background: rgba(110, 168, 254, 0.06);
  border-radius: 0 6px 6px 0;
  line-height: 1.4;
}

a.citation {
  color: var(--accent);
  text-decoration: none;
  opacity: 0.75;
}

a.citation:hover {
  opacity: 1;
  text-decoration: underline;
}

/* Parameter sliders */
.param-slider-row {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 2px 2px;
}

.param-slider {
  flex: 1;
  min-width: 0;
  height: 4px;
  cursor: pointer;
  accent-color: var(--accent);
  -webkit-appearance: none;
  appearance: none;
  background: var(--border);
  border-radius: 2px;
  outline: none;
}

.param-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel);
  cursor: grab;
  box-shadow: 0 1px 4px rgba(0,0,0,0.3);
}
.param-slider::-webkit-slider-thumb:active { cursor: grabbing; }

.param-slider::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel);
  cursor: grab;
  box-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

.slider-bound {
  width: 42px;
  flex: 0 0 42px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 10px;
  padding: 2px 4px;
  text-align: center;
  outline: none;
  -moz-appearance: textfield;
}
.slider-bound::-webkit-inner-spin-button,
.slider-bound::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
.slider-bound:focus { border-color: var(--accent); color: var(--text); }
.slider-step { width: 36px; flex-basis: 36px; }

/* Touch-friendly adjustments */
@media (pointer: coarse) {
  .chip { width: 24px; height: 24px; }
  .del { width: 28px; height: 28px; font-size: 20px; }
  .row-input { font-size: 16px; padding: 8px 4px; }
  .keypad button { padding: 12px 0; font-size: 15px; }
  .param-slider::-webkit-slider-thumb { width: 20px; height: 20px; }
  .param-slider::-moz-range-thumb { width: 20px; height: 20px; }
  #canvas { touch-action: none; }
}

/* Prevent iOS text size adjustments */
@media (max-width: 820px) {
  header h1 span[style] { display: none; }
  .panel-header span[style] { display: none; }
  #canvas { touch-action: none; }
  .graph-credit {
    left: 12px;
    right: 12px;
    bottom: 12px;
    justify-content: space-between;
    gap: 10px;
    border-radius: 14px;
  }
}