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

:root {
  --bg:           #121218;
  --panel:        #28282e;
  --panel-border: #3c3c46;
  --surface:      #1c1c24;
  --text:         #dcdce6;
  --text-dim:     #8c8c9e;
  --accent-rl:    #64a0ff;
  --accent-maxrl: #ff8c3c;
  --accent-green: #00c850;
  --divider:      #3c3c4b;
  --ctrl-bg:      #22222a;
  --ctrl-hover:   #32323c;
  --ctrl-active:  #3a3a48;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", "Helvetica Neue", Arial, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
  overflow-x: hidden;
}

/* ── Header ───────────────────────────────────────────────────────── */
#header {
  text-align: center;
  padding: 18px 20px 6px;
}

#header h1 {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: var(--text);
}

#header .citation {
  font-size: 12px;
  color: var(--text-dim);
  margin-top: 2px;
}

#header .citation em {
  color: var(--text-dim);
}

#header .site-backlink {
  font-size: 11px;
  margin-top: 4px;
}

#header .site-backlink a {
  color: var(--text-dim);
  text-decoration: none;
  opacity: 0.8;
}

#header .site-backlink a:hover {
  color: var(--text);
  opacity: 1;
}

/* ── Control bar ──────────────────────────────────────────────────── */
#controls {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 10px;
  margin: 6px 0 10px;
  flex-wrap: wrap;
  justify-content: center;
}

.ctrl-group {
  display: flex;
  align-items: center;
  gap: 4px;
}

.ctrl-sep {
  width: 1px;
  height: 24px;
  background: var(--divider);
  margin: 0 6px;
}

/* Buttons */
.ctrl-btn {
  background: var(--ctrl-bg);
  color: var(--text);
  border: 1px solid var(--panel-border);
  border-radius: 6px;
  padding: 5px 14px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
  user-select: none;
  white-space: nowrap;
}

.ctrl-btn:hover {
  background: var(--ctrl-hover);
  border-color: var(--text-dim);
}

.ctrl-btn:active {
  background: var(--ctrl-active);
}

.ctrl-btn.active {
  background: var(--accent-rl);
  color: #fff;
  border-color: var(--accent-rl);
}

.ctrl-btn.accent-orange {
  background: var(--accent-maxrl);
  color: #fff;
  border-color: var(--accent-maxrl);
}

.ctrl-btn.accent-orange:hover {
  background: #e07828;
}

.ctrl-btn.toggle.on {
  background: var(--accent-rl);
  color: #fff;
  border-color: var(--accent-rl);
}

/* Slider */
.ctrl-label {
  font-size: 12px;
  color: var(--text-dim);
  margin-right: 4px;
  user-select: none;
}

.ctrl-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100px;
  height: 6px;
  border-radius: 3px;
  background: var(--ctrl-bg);
  outline: none;
  cursor: pointer;
}

.ctrl-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent-maxrl);
  border: 2px solid var(--panel);
  cursor: pointer;
}

.ctrl-slider::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent-maxrl);
  border: 2px solid var(--panel);
  cursor: pointer;
}

/* ── Canvas ───────────────────────────────────────────────────────── */
#canvas-wrap {
  display: flex;
  justify-content: center;
  padding: 0 10px;
}

#mainCanvas {
  background: var(--bg);
  border: 1px solid var(--panel-border);
  border-radius: 8px;
  display: block;
  max-width: 100%;
  height: auto;
}

/* ── Formula bar ──────────────────────────────────────────────────── */
#formula-bar {
  display: flex;
  gap: 32px;
  justify-content: center;
  padding: 10px 20px 18px;
  flex-wrap: wrap;
}

.formula {
  font-family: "Courier New", Courier, monospace;
  font-size: 13px;
  letter-spacing: 0.3px;
}

.formula.rl {
  color: var(--accent-rl);
}

.formula.maxrl {
  color: var(--accent-maxrl);
}

/* ── Claude badge ────────────────────────────────────────────────── */
#claude-badge {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  opacity: 0.55;
  transition: opacity 0.2s;
}

#claude-badge:hover {
  opacity: 0.9;
}

#claude-badge span {
  font-size: 11px;
  color: #D97757;
  font-weight: 500;
  letter-spacing: 0.3px;
}