:root {
  --accent3:#F1C0D0;
  --input-bg:rgba(255,255,255,0.06);--card-bg:rgba(255,255,255,0.03);
  --value-highlight:#8DBBFF;
}
body.light {
  --accent:#8BB8F8;--accent-strong:#5A91E8;--accent2:#B8E0D2;--accent3:#FFD6E0;
  --input-bg:rgba(0,0,0,0.04);--card-bg:rgba(255,255,255,0.85);
  --shadow:0 2px 16px rgba(120,160,220,0.10);--shadow-lg:0 4px 32px rgba(120,160,220,0.14);
  --value-highlight:#5A91E8;
  --error-bg:#FFB3BA;--error-text:#4A1018;
}
*{box-sizing:border-box;min-width:0}
body{margin:0;font-family:'DM Sans',system-ui,sans-serif;font-size:15px;line-height:1.5;color:var(--text);background:var(--bg);transition:background .25s,color .25s;overflow-x:hidden}
.container{max-width:1440px;margin:0 auto;padding:24px}

/* HEADER */
.header{padding:20px 28px;margin-bottom:18px;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:12px;background:var(--card-bg);border:1px solid var(--border);border-radius:14px;box-shadow:var(--shadow)}
.header-left h1{margin:0 0 2px;font-size:1.75rem;font-weight:800;letter-spacing:-.02em}
.header-left p{color:var(--muted);margin:0;font-size:.88rem}
.header-right{display:flex;gap:10px;align-items:center;flex-wrap:wrap}

/* LAYOUT */
.layout{display:grid;grid-template-columns:360px 1fr;gap:18px;align-items:start}
.sidebar{display:flex;flex-direction:column;gap:12px;position:sticky;top:16px}

/* CARD */
.card{background:var(--card-bg);border:1px solid var(--border);border-radius:14px;box-shadow:var(--shadow)}

/* CONTROL PANEL */
.ctrl-tabs{display:flex;border-bottom:1px solid var(--border)}
.ctrl-tab{flex:1;padding:12px 8px;text-align:center;font-weight:700;font-size:.85rem;cursor:pointer;color:var(--muted);background:transparent;border:none;border-bottom:2px solid transparent;margin-bottom:-1px;transition:all 150ms;font-family:inherit}
.ctrl-tab.active{color:var(--text);border-bottom-color:var(--accent)}
.ctrl-panel{display:none;padding:16px 18px 18px}
.ctrl-panel.active{display:block}

/* VISUALISE BUTTON — always visible below sidebar */
.btn-visualise{width:100%;padding:13px 22px;background:var(--accent);color:var(--text-inv);border:none;border-radius:12px;font-weight:800;font-size:.95rem;cursor:pointer;transition:opacity 150ms,transform 150ms;font-family:inherit;letter-spacing:.01em;display:flex;align-items:center;justify-content:center;gap:8px;box-shadow:0 4px 18px rgba(141,187,255,.2)}
.btn-visualise:hover{opacity:.88}
.btn-visualise:active{transform:scale(.97)}
.btn-visualise:disabled{opacity:.38;cursor:not-allowed}

/* SECTION TITLE */
.section-title{font-size:.72rem;color:var(--muted);font-weight:700;text-transform:uppercase;letter-spacing:.07em;margin:0 0 10px}

/* FIELD GROUP */
.field-group{margin-bottom:16px}
.field-group:last-child{margin-bottom:0}
.field-group label{display:block;font-weight:700;font-size:.88rem;margin-bottom:6px}
.field-group .help{color:var(--muted);font-size:.79rem;margin-top:4px;line-height:1.4}

/* INPUTS */
select,input[type=number],input[type=text]{width:100%;background:var(--input-bg);border:1px solid var(--border);border-radius:8px;padding:8px 10px;color:var(--text);font-family:'DM Sans',sans-serif;font-variant-numeric:tabular-nums;font-size:.88rem;outline:none;transition:border-color 150ms}
select:focus,input:focus{border-color:var(--accent)}
select option{background:var(--panel);color:var(--text)}

/* DIMENSION BUTTONS */
.dim-btns{display:flex;gap:7px;margin-bottom:6px}
.dim-btn{flex:1;padding:9px 6px;background:var(--input-bg);border:1.5px solid var(--border);border-radius:10px;color:var(--muted);font-weight:700;font-size:.88rem;cursor:pointer;transition:all 150ms;font-family:inherit;text-align:center}
.dim-btn.active{border-color:var(--accent);color:var(--accent);background:rgba(141,187,255,.08)}

/* UPLOAD ZONE */
.upload-zone{border:2px dashed var(--border);border-radius:12px;padding:24px 16px;text-align:center;cursor:pointer;transition:all 200ms;margin-bottom:14px;position:relative}
.upload-zone:hover,.upload-zone.drag{border-color:var(--accent);background:rgba(141,187,255,.04)}
.upload-zone input{position:absolute;inset:0;opacity:0;cursor:pointer;width:100%;height:100%}
.upload-icon{font-size:1.8rem;margin-bottom:6px}
.upload-text{font-weight:600;font-size:.88rem;margin-bottom:3px}
.upload-sub{color:var(--muted);font-size:.78rem}
.file-name{font-family:'DM Mono',monospace;font-size:.78rem;color:var(--accent2);margin-top:8px;word-break:break-all}

/* BUTTONS */
.btn-secondary{background:var(--input-bg);color:var(--text);border:1px solid var(--border);border-radius:9px;padding:7px 14px;font-weight:700;font-size:.83rem;cursor:pointer;transition:border-color 150ms;font-family:inherit;display:inline-flex;align-items:center;gap:6px;white-space:nowrap}
.btn-secondary:hover{border-color:var(--accent)}
.btn-secondary:active{transform:scale(.97)}
.btn-theme{background:var(--input-bg);border:1px solid var(--border);color:var(--muted);border-radius:10px;padding:8px 14px;font-size:.85rem;font-weight:600;cursor:pointer;transition:all 150ms;white-space:nowrap;font-family:inherit}
.btn-theme:hover{border-color:var(--accent);color:var(--text)}
.btn-back{text-decoration:none;display:inline-flex;align-items:center;}

/* CHART PANEL */
.chart-panel{position:relative;overflow:hidden}
.chart-header{padding:14px 18px 12px;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:10px;border-bottom:1px solid var(--border)}
.chart-header-left{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.chart-header h2{margin:0;font-size:1.05rem;font-weight:700}
.info-row{display:flex;gap:8px;flex-wrap:wrap;padding:9px 18px;font-size:.79rem;color:var(--muted);border-bottom:1px solid var(--border)}
.info-chip{background:var(--input-bg);border:1px solid var(--border);border-radius:7px;padding:3px 9px}
.info-chip strong{color:var(--text)}
#plotDiv{width:100%;height:540px}

/* EMPTY STATE */
.empty-state{display:flex;flex-direction:column;align-items:center;justify-content:center;height:480px;color:var(--muted);gap:12px}
.empty-state .icon{font-size:2.8rem;opacity:.35}
.empty-state p{font-size:.88rem;text-align:center;max-width:240px;line-height:1.5}

/* BADGES */
.badge{border-radius:999px;padding:2px 9px;font-size:.73rem;font-weight:700;display:inline-block}
.badge-success{background:var(--success-bg);color:var(--success-text)}
.badge-error{background:var(--error-bg);color:var(--error-text)}
.badge-info{background:var(--info-bg);color:var(--info-text)}
.badge-warning{background:var(--warning-bg);color:var(--warning-text)}

/* SERIES COLOUR ROWS — inline label + swatch */
.color-series-list{display:flex;flex-direction:column;gap:6px}
.color-series-row{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:7px 10px;background:var(--input-bg);border:1px solid var(--border);border-radius:9px}
.color-series-name{font-size:.84rem;font-weight:600;flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.color-series-picker{width:32px;height:26px;border:2px solid var(--border);background:none;cursor:pointer;padding:2px;border-radius:6px;overflow:hidden;flex-shrink:0}

/* COLORMAP GRID */
.colormap-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:6px;margin-top:6px}
.colormap-btn{padding:7px 6px;background:var(--input-bg);border:1.5px solid var(--border);border-radius:8px;cursor:pointer;font-size:.76rem;font-weight:700;color:var(--muted);text-align:center;transition:all 150ms;font-family:inherit}
.colormap-btn.active{border-color:var(--accent);color:var(--accent);background:rgba(141,187,255,.08)}
.colormap-preview{height:7px;border-radius:4px;margin-bottom:4px}

/* SEPARATOR */
hr.sep{border:none;border-top:1px solid var(--border);margin:14px 0}

/* FOOTER */
.page-footer{max-width:1440px;margin:0 auto;padding:0 24px 24px}
.page-footer-info p:last-child{margin-bottom:0}

/* RESPONSIVE */
@media(max-width:1100px){
  .layout{grid-template-columns:1fr}
  .sidebar{position:static}
  #plotDiv{height:420px}
}
@media(max-width:600px){
  .header{padding:14px 16px}
  .container{padding:10px}
  h1{font-size:1.35rem}
}