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

:root {
  --bg:        #0a0a0c;
  --surface:   #111116;
  --panel:     #18181f;
  --border:    #2a2a35;
  --border-hi: #3d3d50;
  --text:      #e8e8f0;
  --muted:     #666680;
  --accent:    #7c6aff;
  --accent-lo: rgba(124,106,255,.15);
  --red:       #ff5c5c;
  --mono:      'Space Mono', monospace;
  --sans:      'Syne', sans-serif;
  --radius:    8px;
  --track-h:   4px;
  --thumb-sz:  16px;
}

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 13px;
  overflow: hidden;
}

/* ── Layout ────────────────────────────────────────────────── */
#app {
  display: grid;
  grid-template-columns: 1fr 380px;
  height: 100vh;
}

/* ── Preview Pane ──────────────────────────────────────────── */
#preview-pane {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  overflow: hidden;
}

#preview-pane::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: .35;
  pointer-events: none;
}

#gradient-canvas {
  position: relative;
  width: min(90%, 520px);
  aspect-ratio: 4/3;
  border-radius: 16px;
  box-shadow: 0 32px 80px rgba(0,0,0,.7), 0 0 0 1px var(--border);
  transition: background 0.2s ease;
  overflow: hidden;
}

/* ── Control Panel ─────────────────────────────────────────── */
#control-panel {
  background: var(--surface);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  overflow-x: hidden;
}

#control-panel::-webkit-scrollbar { width: 4px; }
#control-panel::-webkit-scrollbar-track { background: transparent; }
#control-panel::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

/* ── Panel Header ──────────────────────────────────────────── */
.panel-header {
  padding: 20px 20px 16px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.panel-header h1 {
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -.5px;
  line-height: 1;
  color: var(--text);
}

.panel-header .version-badge {
  display: inline-block;
  margin-left: 8px;
  padding: 2px 6px;
  background: var(--accent-lo);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 10px;
  border-radius: 4px;
  letter-spacing: .5px;
  border: 1px solid rgba(124,106,255,.3);
  vertical-align: middle;
  position: relative;
  top: -2px;
}

/* ── Section ───────────────────────────────────────────────── */
.section {
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
}

.section-label {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 12px;
}

/* ── Color Stops ───────────────────────────────────────────── */
#stops-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 10px;
}

.stop-row {
  display: grid;
  grid-template-columns: 32px 1fr 56px 28px;
  align-items: center;
  gap: 8px;
  padding: 6px 8px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: border-color .15s;
}

.stop-row:hover { border-color: var(--border-hi); }

.stop-swatch {
  width: 32px;
  height: 32px;
  border-radius: 6px;
  border: 2px solid rgba(255,255,255,.1);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  flex-shrink: 0;
}

.stop-swatch::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,.15) 0%, transparent 60%);
  pointer-events: none;
}

.stop-swatch input[type="color"] {
  position: absolute;
  inset: -4px;
  width: calc(100% + 8px);
  height: calc(100% + 8px);
  opacity: 0;
  cursor: pointer;
  border: none;
}

.stop-pos-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: var(--track-h);
  background: var(--border);
  border-radius: 2px;
  outline: none;
  cursor: pointer;
}

.stop-pos-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: var(--thumb-sz);
  height: var(--thumb-sz);
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
  box-shadow: 0 0 6px rgba(124,106,255,.5);
  cursor: grab;
  transition: transform .1s, box-shadow .1s;
}

.stop-pos-slider::-webkit-slider-thumb:active { cursor: grabbing; transform: scale(1.2); }

.stop-pos-num {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  text-align: right;
  min-width: 36px;
}

.stop-delete {
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 4px;
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
  line-height: 1;
  transition: color .15s, border-color .15s, background .15s;
}

.stop-delete:hover { color: var(--red); border-color: rgba(255,92,92,.3); background: rgba(255,92,92,.08); }
.stop-delete:disabled { opacity: .25; pointer-events: none; }

#add-stop-btn {
  width: 100%;
  padding: 8px;
  background: transparent;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  color: var(--muted);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .5px;
  cursor: pointer;
  transition: border-color .15s, color .15s, background .15s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

#add-stop-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-lo);
}

/* ── Gradient Type Tabs ────────────────────────────────────── */
.type-tabs {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 4px;
  background: var(--panel);
  padding: 4px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.type-tab {
  padding: 7px 4px;
  background: transparent;
  border: none;
  border-radius: 5px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: .3px;
  cursor: pointer;
  transition: background .15s, color .15s;
  text-align: center;
}

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

.type-tab.active {
  background: var(--accent);
  color: #fff;
  font-weight: 700;
}

/* ── Sliders ────────────────────────────────────────────────── */
.slider-row {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.slider-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

.slider-name {
  font-size: 12px;
  color: var(--muted);
}

.slider-value {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text);
}

.range-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: var(--track-h);
  background: var(--border);
  border-radius: 2px;
  outline: none;
  cursor: pointer;
}

.range-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: var(--thumb-sz);
  height: var(--thumb-sz);
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
  box-shadow: 0 0 6px rgba(124,106,255,.5);
  cursor: grab;
  transition: transform .1s;
}

.range-slider::-webkit-slider-thumb:active { cursor: grabbing; transform: scale(1.2); }

/* ── Precision Toggle ───────────────────────────────────────── */
.precision-row {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 12px;
}

.toggle-group {
  display: flex;
  gap: 3px;
  background: var(--panel);
  padding: 3px;
  border-radius: 6px;
  border: 1px solid var(--border);
}

.toggle-btn {
  padding: 4px 10px;
  background: transparent;
  border: none;
  border-radius: 4px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 10px;
  cursor: pointer;
  transition: background .15s, color .15s;
}

.toggle-btn.active {
  background: var(--border-hi);
  color: var(--text);
}

/* ── CSS Output ─────────────────────────────────────────────── */
#css-output {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 14px;
  font-family: var(--mono);
  font-size: 11px;
  line-height: 1.7;
  color: #a0a0c0;
  word-break: break-all;
  min-height: 60px;
  transition: border-color .15s;
  cursor: pointer;
}

#css-output:hover { border-color: var(--border-hi); }

#css-output .kw  { color: #7c6aff; }
#css-output .fn  { color: #52d9b5; }
#css-output .val { color: #ffb86c; }
#css-output .num { color: #ff79c6; }

.copy-hint {
  font-size: 10px;
  color: var(--muted);
  margin-top: 6px;
  font-family: var(--mono);
  letter-spacing: .3px;
}

/* ── Actions ────────────────────────────────────────────────── */
.actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.btn {
  padding: 10px 16px;
  border-radius: var(--radius);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .5px;
  font-weight: 700;
  cursor: pointer;
  border: none;
  transition: transform .1s, box-shadow .15s, opacity .15s;
  text-transform: uppercase;
}

.btn:active { transform: scale(.97); }

.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 4px 16px rgba(124,106,255,.35);
}

.btn-primary:hover { box-shadow: 0 6px 24px rgba(124,106,255,.5); }

.btn-secondary {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover { border-color: var(--border-hi); }

/* ── Toast ──────────────────────────────────────────────────── */
#toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(60px);
  background: var(--text);
  color: var(--bg);
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  padding: 10px 20px;
  border-radius: 100px;
  pointer-events: none;
  opacity: 0;
  transition: transform .3s cubic-bezier(.34,1.56,.64,1), opacity .3s;
  z-index: 1000;
  letter-spacing: .5px;
}

#toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

/* ── Responsive ─────────────────────────────────────────────── */
@media (max-width: 700px) {
  #app { grid-template-columns: 1fr; grid-template-rows: 40vh 1fr; overflow: auto; }
  #preview-pane { min-height: 200px; }
  #control-panel { overflow-y: auto; }
  html, body { overflow: auto; }
}