:root {
  --bg-dark: #0b101b;
  --bg-panel: #131b2e;
  --bg-card: #1a253d;
  --bg-card-hover: #212f4d;
  --border: #2a3958;
  --text-main: #e2e8f0;
  --text-muted: #94a3b8;
  --accent-cyan: #38bdf8;
  --accent-amber: #f59e0b;
  --accent-red: #ef4444;
  --accent-green: #10b981;
  --accent-purple: #a855f7;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Menlo, Monaco, Consolas, monospace;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.5;
  min-height: 100vh;
}

/* Top Header */
.top-header {
  background: linear-gradient(90deg, #0f172a 0%, #172554 100%);
  border-bottom: 1px solid var(--border);
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.brand-block {
  display: flex;
  align-items: center;
  gap: 14px;
}

.brand-badge {
  background: rgba(56, 189, 248, 0.15);
  border: 1px solid var(--accent-cyan);
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 11px;
  padding: 4px 8px;
  border-radius: 4px;
  letter-spacing: 0.08em;
}

.brand-title h1 {
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.brand-title p {
  font-size: 12px;
  color: var(--text-muted);
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.status-pill {
  padding: 5px 12px;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.status-pill.ch1 {
  background: rgba(245, 158, 11, 0.16);
  border: 1px solid var(--accent-amber);
  color: #fbbf24;
}

.status-pill.ch2 {
  background: rgba(239, 68, 68, 0.18);
  border: 1px solid var(--accent-red);
  color: #f87171;
}

.status-pill.ch3 {
  background: rgba(168, 85, 247, 0.18);
  border: 1px solid var(--accent-purple);
  color: #c084fc;
}

.btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-main);
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
  font-weight: 600;
  transition: all 0.15s ease;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

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

.btn.primary {
  background: #0284c7;
  border-color: #38bdf8;
  color: #fff;
}

.btn.primary:hover {
  background: #0369a1;
}

.btn.amber {
  background: rgba(245, 158, 11, 0.2);
  border-color: var(--accent-amber);
  color: #fcd34d;
}

.btn.danger {
  background: rgba(239, 68, 68, 0.2);
  border-color: var(--accent-red);
  color: #fca5a5;
}

.btn.success {
  background: rgba(16, 185, 129, 0.2);
  border-color: var(--accent-green);
  color: #6ee7b7;
}

/* Chapter Banner & Navigation Tabs */
.chapter-strip {
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border);
  padding: 10px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.chapter-steps {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.chapter-step {
  padding: 6px 14px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg-dark);
  color: var(--text-muted);
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
}

.chapter-step.active {
  border-color: var(--accent-cyan);
  background: rgba(56, 189, 248, 0.14);
  color: #fff;
}

.chapter-step.locked {
  opacity: 0.45;
  cursor: not-allowed;
}

.roster-funnel {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
}

.funnel-badge {
  padding: 3px 8px;
  border-radius: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border);
}

/* Main Navigation Tabs */
.nav-tabs {
  display: flex;
  gap: 4px;
  padding: 12px 24px 0;
  border-bottom: 1px solid var(--border);
  background: #0e1525;
  overflow-x: auto;
}

.nav-tab {
  padding: 10px 18px;
  background: transparent;
  border: 1px solid transparent;
  border-bottom: none;
  color: var(--text-muted);
  font-weight: 600;
  font-size: 13px;
  cursor: pointer;
  border-radius: 8px 8px 0 0;
  white-space: nowrap;
}

.nav-tab:hover {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.03);
}

.nav-tab.active {
  background: var(--bg-dark);
  border-color: var(--border);
  color: var(--accent-cyan);
}

/* Workspace Layout */
.workspace {
  display: grid;
  grid-template-columns: 1fr 310px;
  gap: 18px;
  padding: 18px 24px;
  max-width: 1680px;
  margin: 0 auto;
}

@media (max-width: 1180px) {
  .workspace {
    grid-template-columns: 1fr;
  }
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: block;
}

.panel-card {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  margin-bottom: 16px;
}

.panel-card h2 {
  font-size: 16px;
  margin-bottom: 8px;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.panel-card h3 {
  font-size: 14px;
  margin-bottom: 8px;
  color: var(--accent-cyan);
}

/* Briefing Grid */
.briefing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 14px;
  margin-top: 12px;
}

.narrative-box {
  background: var(--bg-card);
  border-left: 3px solid var(--accent-cyan);
  padding: 14px;
  border-radius: 6px;
  font-size: 13.5px;
  line-height: 1.6;
}

/* Interactive Architecture SVG Diagram */
.diagram-container {
  background: #090d16;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
  margin-top: 12px;
  overflow-x: auto;
}

.arch-node {
  cursor: pointer;
  transition: all 0.15s ease;
}

.arch-node:hover rect {
  stroke: #38bdf8;
  stroke-width: 2.5px;
  fill: #1e293b;
}

/* Repository & Artifact Explorer */
.repo-layout {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 16px;
}

@media (max-width: 960px) {
  .repo-layout {
    grid-template-columns: 1fr;
  }
}

.repo-filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 12px;
}

.repo-pill {
  padding: 5px 10px;
  font-size: 11px;
  font-family: var(--font-mono);
  border-radius: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
}

.repo-pill.active {
  background: rgba(56, 189, 248, 0.18);
  border-color: var(--accent-cyan);
  color: #fff;
}

.artifact-list {
  max-height: 650px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding-right: 4px;
}

.artifact-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 12px;
  cursor: pointer;
  transition: all 0.12s ease;
}

.artifact-item:hover {
  border-color: var(--accent-cyan);
  background: var(--bg-card-hover);
}

.artifact-item.active {
  border-color: var(--accent-cyan);
  background: rgba(56, 189, 248, 0.12);
}

.artifact-item-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  margin-bottom: 4px;
}

.artifact-id {
  color: var(--accent-cyan);
  font-weight: 700;
}

.artifact-repo-tag {
  background: #0f172a;
  padding: 2px 6px;
  border-radius: 3px;
  color: var(--text-muted);
}

.artifact-title {
  font-weight: 600;
  font-size: 13px;
  color: #fff;
}

.artifact-viewer {
  background: #090d16;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 18px;
}

.artifact-meta-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 12px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.code-block {
  background: #05080f;
  border: 1px solid #1e293b;
  border-radius: 6px;
  padding: 14px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 1.55;
  white-space: pre-wrap;
  overflow-x: auto;
  color: #cbd5e1;
}

/* Side-by-Side Diff Viewer */
.diff-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 12px;
}

@media (max-width: 900px) {
  .diff-grid {
    grid-template-columns: 1fr;
  }
}

.diff-col h4 {
  font-family: var(--font-mono);
  font-size: 12px;
  margin-bottom: 6px;
  padding: 6px 10px;
  background: var(--bg-card);
  border-radius: 4px;
}

/* Employee Suspect Board */
.board-stats {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 14px;
  font-family: var(--font-mono);
  font-size: 12px;
}

.employee-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 12px;
}

.emp-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 8px;
}

.emp-card.status-investigate {
  border-color: var(--accent-amber);
  background: rgba(245, 158, 11, 0.07);
}

.emp-card.status-cleared {
  border-color: #334155;
  opacity: 0.72;
}

.emp-card.status-insider {
  border-color: var(--accent-red);
  background: rgba(239, 68, 68, 0.14);
}

.emp-card.status-misconduct {
  border-color: var(--accent-purple);
  background: rgba(168, 85, 247, 0.1);
}

.emp-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.emp-id {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--accent-cyan);
  font-weight: 700;
}

.emp-name {
  font-size: 14px;
  font-weight: 700;
  color: #fff;
}

.emp-role {
  font-size: 12px;
  color: var(--text-muted);
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.tag {
  font-family: var(--font-mono);
  font-size: 10px;
  padding: 2px 6px;
  border-radius: 3px;
  background: #0f172a;
  color: #93c5fd;
  border: 1px solid #1e3a8a;
}

/* Milestones & IR Cards */
.milestone-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  margin-bottom: 14px;
}

.milestone-option {
  background: #0f172a;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 12px;
  margin-top: 8px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.milestone-option:hover {
  border-color: var(--accent-cyan);
}

.milestone-option.locked-correct {
  border-color: var(--accent-green);
  background: rgba(16, 185, 129, 0.14);
}

.vote-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  padding: 3px 8px;
  border-radius: 999px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  white-space: nowrap;
}

/* Right Classroom Sidebar */
.sidebar-feed {
  max-height: 440px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.feed-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 10px;
  font-size: 12px;
}

.feed-time {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--accent-cyan);
}

input[type="text"], select {
  background: #090d16;
  border: 1px solid var(--border);
  color: var(--text-main);
  padding: 6px 10px;
  border-radius: 5px;
  font-size: 12px;
}