/* ===== DESIGN TOKENS ===== */
:root {
  --bg: #0a0c14;
  --bg-card: #111520;
  --bg-card-hover: #161b2a;
  --border: rgba(255,255,255,0.07);
  --border-strong: rgba(255,255,255,0.14);
  --accent: #6c63ff;
  --accent-glow: rgba(108,99,255,0.35);
  --accent2: #00d4aa;
  --accent2-glow: rgba(0,212,170,0.25);
  --warn: #f59e0b;
  --warn-glow: rgba(245,158,11,0.25);
  --danger: #ef4444;
  --danger-glow: rgba(239,68,68,0.2);
  --success: #22c55e;
  --success-glow: rgba(34,197,94,0.2);
  --text: #e2e8f0;
  --text-muted: #64748b;
  --text-dim: #94a3b8;
  --font: 'Inter', sans-serif;
  --mono: 'JetBrains Mono', monospace;
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.2s cubic-bezier(0.4,0,0.2,1);
}

/* ===== BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.6;
  min-height: 100vh;
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(108,99,255,0.15), transparent),
    radial-gradient(ellipse 60% 40% at 80% 100%, rgba(0,212,170,0.08), transparent);
}

#app { max-width: 1200px; margin: 0 auto; padding: 0 1.5rem 4rem; }

/* ===== HEADER ===== */
.app-header {
  padding: 2.5rem 0 2rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2.5rem;
}

.header-inner { text-align: center; }

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.logo-icon { font-size: 1.8rem; filter: drop-shadow(0 0 12px rgba(108,99,255,0.8)); }
.logo-accent { color: var(--accent); }

.header-sub {
  color: var(--text-muted);
  margin-top: 0.4rem;
  font-size: 0.9rem;
  letter-spacing: 0.02em;
}

/* ===== STEP SECTIONS ===== */
.step-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 1.5rem;
  transition: border-color var(--transition);
}

.step-section:hover { border-color: var(--border-strong); }
.step-section.hidden { display: none; }

.step-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.75rem;
}

.step-badge {
  background: linear-gradient(135deg, var(--accent), #9c63ff);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  padding: 0.3rem 0.6rem;
  border-radius: 6px;
  box-shadow: 0 0 16px var(--accent-glow);
  flex-shrink: 0;
}

.step-header h2 {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

/* ===== UPLOAD ===== */
.upload-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1rem;
  align-items: center;
}

.upload-arrow {
  font-size: 2rem;
  color: var(--accent);
  text-shadow: 0 0 20px var(--accent-glow);
  text-align: center;
}

.upload-card {
  background: var(--bg);
  border: 2px dashed var(--border-strong);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  text-align: center;
  transition: all var(--transition);
  cursor: pointer;
}

.upload-card:hover,
.upload-card.drag-over {
  border-color: var(--accent);
  background: rgba(108,99,255,0.05);
  box-shadow: 0 0 30px var(--accent-glow);
}

.upload-card.loaded {
  border-color: var(--success);
  border-style: solid;
  background: rgba(34,197,94,0.04);
}

.upload-icon { font-size: 2.5rem; margin-bottom: 0.75rem; }

.upload-label {
  font-weight: 600;
  font-size: 1rem;
  margin-bottom: 0.35rem;
}

.upload-hint {
  color: var(--text-muted);
  font-size: 0.8rem;
  margin-bottom: 1rem;
}

.file-status {
  margin-top: 0.75rem;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--success);
  min-height: 1.2em;
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.6rem 1.4rem;
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent) 0%, #9c63ff 100%);
  color: #fff;
  box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 6px 28px var(--accent-glow);
}

.btn-primary:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
}

.btn-outline {
  background: transparent;
  color: var(--text-dim);
  border: 1px solid var(--border-strong);
}

.btn-outline:hover {
  background: var(--bg-card-hover);
  color: var(--text);
  border-color: var(--accent);
}

.step-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

/* ===== COLUMN CONFIG ===== */
.config-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.config-panel {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.panel-title {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.panel-subtitle {
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 400;
  margin-left: 0.3rem;
}

.col-legend {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.legend-dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.dot-pa { background: var(--accent); box-shadow: 0 0 6px var(--accent-glow); }
.dot-ra { background: var(--accent2); box-shadow: 0 0 6px var(--accent2-glow); }
.dot-zero { background: var(--text-muted); }

.col-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  max-height: 400px;
  overflow-y: auto;
  padding-right: 0.25rem;
}

.col-list::-webkit-scrollbar { width: 4px; }
.col-list::-webkit-scrollbar-track { background: transparent; }
.col-list::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 99px; }

.col-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.6rem 0.8rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all var(--transition);
  user-select: none;
}

.col-item:hover { background: var(--bg-card-hover); border-color: var(--border-strong); }

.col-item.selected { border-color: var(--accent); background: rgba(108,99,255,0.08); }
.col-item.type-ra.selected { border-color: var(--accent2); background: rgba(0,212,170,0.07); }
.col-item.type-ra .col-type-badge { background: rgba(0,212,170,0.15); color: var(--accent2); }

.col-item.all-zero { opacity: 0.55; }
.col-item.all-zero .col-name::after {
  content: " (all zero)";
  color: var(--text-muted);
  font-size: 0.75em;
}

.col-checkbox {
  width: 16px;
  height: 16px;
  border-radius: 4px;
  border: 1.5px solid var(--border-strong);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 10px;
  transition: all var(--transition);
}

.col-item.selected .col-checkbox {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.col-item.type-ra.selected .col-checkbox {
  background: var(--accent2);
  border-color: var(--accent2);
}

.col-name {
  font-size: 0.82rem;
  font-family: var(--mono);
  flex: 1;
}

.col-type-badge {
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  padding: 0.15rem 0.45rem;
  border-radius: 4px;
  background: rgba(108,99,255,0.15);
  color: var(--accent);
}

.col-pts {
  font-size: 0.72rem;
  color: var(--text-muted);
  flex-shrink: 0;
}

/* Canvas column target */
.canvas-target-group { display: flex; flex-direction: column; gap: 0.5rem; }
.target-label { font-size: 0.82rem; color: var(--text-dim); font-weight: 500; }

.select-input {
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: var(--font);
  font-size: 0.875rem;
  padding: 0.6rem 0.85rem;
  width: 100%;
  appearance: none;
  cursor: pointer;
  transition: border-color var(--transition);
}

.select-input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-glow); }
.select-input option { background: #1a1f30; }

.formula-note {
  margin-top: 1.5rem;
  background: rgba(108,99,255,0.08);
  border: 1px solid rgba(108,99,255,0.2);
  border-radius: var(--radius-sm);
  padding: 0.75rem 1rem;
  font-size: 0.78rem;
  color: var(--text-dim);
  display: flex;
  gap: 0.6rem;
}

.formula-icon { color: var(--accent); font-style: normal; flex-shrink: 0; margin-top: 0.1rem; }
.formula-note code { font-family: var(--mono); color: var(--accent2); font-size: 0.85em; }

/* ===== STATS BAR ===== */
.stats-bar {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.stat-chip {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.6rem 1rem;
  border-radius: 99px;
  font-size: 0.8rem;
  font-weight: 600;
  border: 1px solid;
}

.stat-chip.success {
  background: var(--success-glow);
  border-color: rgba(34,197,94,0.3);
  color: var(--success);
}

.stat-chip.warn {
  background: var(--warn-glow);
  border-color: rgba(245,158,11,0.3);
  color: var(--warn);
}

.stat-chip.danger {
  background: var(--danger-glow);
  border-color: rgba(239,68,68,0.3);
  color: var(--danger);
}

.stat-chip.info {
  background: var(--accent-glow);
  border-color: rgba(108,99,255,0.3);
  color: var(--accent);
}

/* ===== DATA TABLES ===== */
.table-section { margin-bottom: 2rem; }

.table-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

.table-wrap {
  overflow-x: auto;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.8rem;
}

.data-table th {
  background: rgba(255,255,255,0.04);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

.data-table td {
  padding: 0.7rem 1rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.data-table tr:last-child td { border-bottom: none; }

.data-table tbody tr { transition: background var(--transition); }
.data-table tbody tr:hover { background: var(--bg-card-hover); }

.data-table tbody tr.has-note { background: rgba(245,158,11,0.04); }
.data-table tbody tr.has-note:hover { background: rgba(245,158,11,0.08); }

.method-badge {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
  letter-spacing: 0.04em;
}

.method-studentid { background: rgba(34,197,94,0.15); color: var(--success); }
.method-email { background: rgba(245,158,11,0.15); color: var(--warn); }
.method-name { background: rgba(239,68,68,0.15); color: var(--danger); }

.score-cell {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--accent2);
  font-weight: 500;
}

.score-na { color: var(--text-muted); font-style: italic; }

.note-cell {
  color: var(--warn);
  font-size: 0.75rem;
  max-width: 200px;
}

/* ===== UNMATCHED ===== */
.unmatched-hint {
  color: var(--text-muted);
  font-size: 0.82rem;
  margin-bottom: 1rem;
}

.unmatched-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.unmatched-panel {
  background: var(--bg);
  border: 1px solid rgba(239,68,68,0.2);
  border-radius: var(--radius);
  padding: 1rem;
}

.unmatched-panel h4 {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--danger);
  margin-bottom: 0.75rem;
}

.unmatched-list {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  max-height: 250px;
  overflow-y: auto;
}

.unmatched-item {
  font-size: 0.78rem;
  padding: 0.4rem 0.6rem;
  background: rgba(239,68,68,0.05);
  border-radius: 6px;
  border: 1px solid rgba(239,68,68,0.1);
  font-family: var(--mono);
}

.unmatched-item .uname { color: var(--text-dim); }
.unmatched-item .email { color: var(--text-muted); font-size: 0.72em; }

/* ===== EXPORT ACTIONS ===== */
.export-actions {
  justify-content: center;
  gap: 1rem;
  padding-top: 0.5rem;
}

.export-actions .btn-primary { padding: 0.75rem 2rem; font-size: 0.95rem; }

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar { width: 6px; height: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 99px; }

/* ===== RESPONSIVE ===== */
@media (max-width: 800px) {
  .upload-grid { grid-template-columns: 1fr; }
  .upload-arrow { transform: rotate(90deg); }
  .config-grid { grid-template-columns: 1fr; }
  .unmatched-grid { grid-template-columns: 1fr; }
}