:root {
  --bg:       #080612;
  --panel:    #0f0c22;
  --panel2:   #1a1535;
  --border:   #2a2350;
  --accent:   #7c3aed;
  --accent2:  #a855f7;
  --accent3:  #c084fc;
  --glow:     rgba(124,58,237,0.45);
  --text:     #e2d9f3;
  --muted:    #6b5f8a;
  --danger:   #f43f5e;
  --topbar-h: 48px;
  --panel-w:  272px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; background: var(--bg); color: var(--text); font-family: 'Segoe UI', system-ui, sans-serif; overflow: hidden; }

/* ── Layout ─────────────────────────────────────────── */
body { display: grid; grid-template-rows: var(--topbar-h) 1fr; }

.app-body {
  display: grid;
  grid-template-columns: 1fr var(--panel-w);
  overflow: hidden;
  transition: grid-template-columns 0.3s ease;
}
.app-body.panel-hidden {
  grid-template-columns: 1fr 0px;
}

/* ── Topbar ─────────────────────────────────────────── */
.topbar {
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 16px;
  box-shadow: 0 2px 24px rgba(124,58,237,0.15);
}
.topbar-logo {
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  background: linear-gradient(90deg, var(--accent2), var(--accent3), #60a5fa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  flex-shrink: 0;
}
.topbar-stats { display: flex; gap: 16px; flex: 1; }
.stat { font-size: 0.7rem; color: var(--muted); }
.stat strong { color: var(--accent3); font-weight: 700; }
.topbar-keys { font-size: 0.65rem; color: var(--muted); flex-shrink: 0; }
kbd {
  background: var(--panel2); border: 1px solid var(--border);
  border-radius: 4px; padding: 1px 5px;
  font-size: 0.63rem; color: var(--accent3); font-family: inherit;
}

/* Panel toggle button */
.panel-toggle-btn {
  width: 32px; height: 32px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel2);
  color: var(--accent3);
  cursor: pointer;
  display: grid; place-items: center;
  flex-shrink: 0;
  transition: background 0.15s, box-shadow 0.15s;
}
.panel-toggle-btn:hover { background: var(--accent); box-shadow: 0 0 10px var(--glow); }
.panel-toggle-btn svg { width: 16px; height: 16px; transition: transform 0.3s; }
.app-body.panel-hidden .panel-toggle-btn svg,
.panel-toggle-btn.flipped svg { transform: rotate(180deg); }

/* ── Canvas ─────────────────────────────────────────── */
#canvasWrap {
  position: relative; overflow: hidden; cursor: crosshair; background: #080612;
}
#canvasWrap canvas { display: block; }

/* ── Panel ─────────────────────────────────────────── */
.panel {
  background: var(--panel);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  width: var(--panel-w);
  transition: transform 0.3s ease, opacity 0.3s ease;
}
.app-body.panel-hidden .panel { transform: translateX(100%); opacity: 0; pointer-events: none; }

.panel::-webkit-scrollbar { width: 3px; }
.panel::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

/* ── Tabs ───────────────────────────────────────────── */
.panel-tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}
.tab-btn {
  flex: 1;
  padding: 10px 4px;
  font-size: 0.63rem;
  font-family: inherit;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--muted);
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
  letter-spacing: 0.02em;
}
.tab-btn:hover { color: var(--accent3); }
.tab-btn.active { color: var(--accent3); border-bottom-color: var(--accent2); }

.tab-content {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
}
.tab-content::-webkit-scrollbar { width: 3px; }
.tab-content::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }
.tab-content.hidden { display: none; }

/* ── Panel sections ─────────────────────────────────── */
.panel-section { padding: 12px 14px; border-bottom: 1px solid var(--border); }
.panel-label {
  font-size: 0.58rem; letter-spacing: 0.14em;
  text-transform: uppercase; color: var(--muted); margin-bottom: 9px;
}
.unit { font-style: normal; color: var(--accent3); font-size: 0.75em; margin-left: 3px; }

/* Shapes */
.shape-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 5px; }
.shape-btn {
  display: flex; flex-direction: column; align-items: center;
  justify-content: center; gap: 3px; padding: 8px 4px;
  border-radius: 8px; border: 1px solid var(--border);
  background: var(--panel2); color: var(--muted);
  font-size: 0.62rem; cursor: pointer; transition: all 0.15s; font-family: inherit;
}
.shape-btn svg { width: 18px; height: 18px; }
.shape-btn:hover, .shape-btn.active {
  border-color: var(--accent2); color: var(--accent3);
  background: rgba(124,58,237,0.18); box-shadow: 0 0 10px var(--glow);
}

/* Colors */
.color-row { display: flex; gap: 6px; flex-wrap: wrap; }
.color-swatch {
  width: 20px; height: 20px; border-radius: 50%;
  border: 2px solid transparent; cursor: pointer;
  transition: transform 0.12s, border-color 0.12s;
}
.color-swatch:hover, .color-swatch.active { transform: scale(1.25); border-color: #fff; }

/* Sliders — label + waarde bovenaan, slider op volledige breedte eronder */
.slider-row {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-rows: auto auto;
  column-gap: 6px;
  row-gap: 3px;
  margin-bottom: 8px;
}
.slider-row label {
  grid-column: 1; grid-row: 1;
  font-size: 0.7rem; color: var(--text);
}
.slider-val {
  grid-column: 2; grid-row: 1;
  font-size: 0.72rem; color: var(--accent3);
  font-weight: 700; text-align: right; white-space: nowrap;
}
.slider-row input[type=range] {
  grid-column: 1 / -1; grid-row: 2;
  width: 100%; accent-color: var(--accent); cursor: pointer; height: 4px;
}

/* Toggles */
.toggle-row { display: flex; align-items: center; justify-content: space-between; margin-bottom: 7px; font-size: 0.72rem; }
.toggle { position: relative; width: 36px; height: 20px; cursor: pointer; }
.toggle input { opacity: 0; width: 0; height: 0; position: absolute; }
.toggle .track { position: absolute; inset: 0; background: var(--border); border-radius: 10px; transition: background 0.2s; }
.toggle input:checked + .track { background: var(--accent); }
.toggle .thumb { position: absolute; top: 3px; left: 3px; width: 14px; height: 14px; background: #fff; border-radius: 50%; transition: transform 0.2s; pointer-events: none; }
.toggle input:checked ~ .thumb { transform: translateX(16px); }

/* Buttons */
.btn-group { display: flex; flex-direction: column; gap: 5px; }
.btn {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 12px; border-radius: 8px;
  border: 1px solid var(--border); background: var(--panel2);
  color: var(--text); font-size: 0.74rem; cursor: pointer;
  transition: background 0.15s, border-color 0.15s, box-shadow 0.15s;
  width: 100%; text-align: left; font-family: inherit;
}
.btn:hover { background: var(--accent); border-color: var(--accent2); box-shadow: 0 0 14px var(--glow); }
.btn:active { transform: scale(0.97); }
.btn.danger:hover { background: var(--danger); border-color: var(--danger); box-shadow: 0 0 14px rgba(244,63,94,0.4); }

/* ── Charts ─────────────────────────────────────────── */
.chart-wrap { position: relative; height: 130px; width: 100%; }
.legend-row { display: flex; align-items: center; gap: 4px; margin-top: 6px; font-size: 0.64rem; color: var(--muted); }
.legend-dot { display: inline-block; width: 8px; height: 8px; border-radius: 50%; }

/* ── Metrics ─────────────────────────────────────────── */
.metric-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; }
.metric {
  background: var(--panel2); border: 1px solid var(--border);
  border-radius: 8px; padding: 7px 9px;
  display: flex; flex-direction: column; gap: 2px;
}
.metric-label { font-size: 0.58rem; color: var(--muted); letter-spacing: 0.05em; }
.metric strong { font-size: 1rem; color: var(--accent3); line-height: 1; font-weight: 700; }
.metric-unit { font-size: 0.58rem; color: var(--muted); font-style: normal; }

/* ── Object tab ─────────────────────────────────────── */
.no-selection {
  text-align: center; color: var(--muted);
  font-size: 0.74rem; line-height: 1.7;
  padding: 16px 0;
}

/* ── Hint ───────────────────────────────────────────── */
.hint { font-size: 0.66rem; color: var(--muted); text-align: center; padding: 12px 14px; line-height: 1.7; }
.hint strong { color: var(--accent3); }

/* ── Uitleg tab ─────────────────────────────────────── */
.uitleg-toggle-bar {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}
.niveau-btn {
  flex: 1;
  padding: 9px 6px;
  font-size: 0.68rem;
  font-family: inherit;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--muted);
  cursor: pointer;
  transition: all 0.15s;
}
.niveau-btn:hover { color: var(--accent3); }
.niveau-btn.active { color: var(--accent3); border-bottom-color: var(--accent2); background: rgba(124,58,237,0.07); }

.niveau-content { padding: 6px 0; }
.niveau-content.hidden { display: none; }

.uitleg-card {
  border-bottom: 1px solid var(--border);
}
.uitleg-card summary {
  padding: 10px 14px;
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--accent3);
  cursor: pointer;
  user-select: none;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 6px;
}
.uitleg-card summary::-webkit-details-marker { display: none; }
.uitleg-card[open] summary { color: #fff; }
.uitleg-card summary::after {
  content: '▸';
  margin-left: auto;
  font-size: 0.6rem;
  color: var(--muted);
  transition: transform 0.2s;
}
.uitleg-card[open] summary::after { transform: rotate(90deg); }

.uitleg-body {
  padding: 0 14px 12px;
  font-size: 0.7rem;
  color: var(--text);
  line-height: 1.6;
}
.uitleg-body p { margin-bottom: 6px; }
.uitleg-body ul, .uitleg-body ol { padding-left: 16px; margin-bottom: 6px; }
.uitleg-body li { margin-bottom: 2px; }

.formule {
  font-size: 1rem;
  font-weight: 700;
  color: var(--accent3);
  text-align: center;
  padding: 8px;
  margin: 6px 0 10px;
  background: var(--panel2);
  border: 1px solid var(--border);
  border-radius: 8px;
  letter-spacing: 0.04em;
}

.uitleg-tip {
  background: rgba(124,58,237,0.1);
  border-left: 3px solid var(--accent);
  border-radius: 0 6px 6px 0;
  padding: 7px 10px;
  margin-top: 8px;
  font-size: 0.67rem;
  color: var(--accent3);
  line-height: 1.5;
}

.formule-tabel {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.67rem;
}
.formule-tabel tr { border-bottom: 1px solid var(--border); }
.formule-tabel td { padding: 5px 4px; vertical-align: top; }
.formule-tabel td:first-child {
  font-family: 'Courier New', monospace;
  color: var(--accent3);
  white-space: nowrap;
  padding-right: 10px;
  width: 44%;
}

/* ── Export buttons ─────────────────────────────────── */
.export-btn {
  background: rgba(16,185,129,0.1);
  border-color: rgba(16,185,129,0.35);
  color: #6ee7b7;
}
.export-btn:hover {
  background: #059669;
  border-color: #10b981;
  box-shadow: 0 0 14px rgba(16,185,129,0.4);
  color: #fff;
}
.export-btn.secondary {
  background: var(--panel2);
  border-color: var(--border);
  color: var(--muted);
}
.export-btn.secondary:hover {
  background: var(--panel2);
  border-color: var(--accent2);
  box-shadow: none;
  color: var(--accent3);
}
.export-hint {
  font-size: 0.6rem;
  color: var(--muted);
  line-height: 1.5;
  margin-top: 7px;
  padding: 0 2px;
}

/* ── Mobile overlay backdrop ────────────────────────── */
.panel-backdrop {
  display: none;
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 90;
}
.panel-backdrop.visible { display: block; }

/* ── Mobile ─────────────────────────────────────────── */
@media (max-width: 768px) {
  .topbar-keys { display: none; }
  .topbar-stats { gap: 10px; }

  .app-body {
    grid-template-columns: 1fr !important;
  }

  .panel {
    position: fixed;
    right: 0;
    top: var(--topbar-h);
    bottom: 0;
    z-index: 100;
    transform: translateX(100%);
    opacity: 1 !important;
    pointer-events: none;
    box-shadow: -8px 0 32px rgba(0,0,0,0.5);
  }
  .panel.mobile-open {
    transform: translateX(0);
    pointer-events: all;
  }
}