:root {
  --bg-app: #090c10;
  --bg-surface: #0d1117;
  --bg-surface-elevated: #161b22;
  --border-subtle: #21262d;
  --border-active: #30363d;
  
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #484f58;

  --accent-blue: #2f81f7;
  --accent-blue-hover: #1f6feb;
  --accent-green: #238636;
  --accent-green-hover: #2ea043;
  --accent-red: #da3633;
  --accent-red-bg: rgba(218, 54, 51, 0.15);

  --font-mono: 'JetBrains Mono', monospace;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

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

body {
  background-color: var(--bg-app);
  color: var(--text-primary);
  font-family: var(--font-sans);
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Navbar */
.navbar {
  height: 52px;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 1.25rem;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-badge {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-active);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--accent-blue);
  letter-spacing: 0.05em;
}

.brand-title {
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

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

.metric-group {
  display: flex;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  overflow: hidden;
}

.metric-item {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  font-size: 0.75rem;
}

.metric-item:first-child {
  border-right: 1px solid var(--border-subtle);
}

.metric-label {
  color: var(--text-secondary);
  font-size: 0.7rem;
  font-family: var(--font-mono);
}

.metric-value {
  font-weight: 600;
  color: var(--text-primary);
}

.select-dropdown {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-active);
  color: var(--text-primary);
  padding: 5px 10px;
  border-radius: 6px;
  font-size: 0.8rem;
  outline: none;
  cursor: pointer;
}

/* Workspace */
.workspace {
  display: grid;
  grid-template-columns: 420px 1fr;
  height: calc(100vh - 52px);
}

.pane {
  padding: 1rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.left-pane {
  border-right: 1px solid var(--border-subtle);
  background: var(--bg-surface);
}

.panel-card {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  padding: 0.85rem;
}

.badge-row {
  display: flex;
  gap: 6px;
  margin-bottom: 6px;
}

.skill-badge {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 600;
  color: var(--accent-blue);
  background: rgba(47, 129, 247, 0.1);
  border: 1px solid rgba(47, 129, 247, 0.2);
  padding: 2px 6px;
  border-radius: 4px;
}

.difficulty-badge {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  padding: 2px 6px;
  border-radius: 4px;
}

.problem-title {
  font-size: 1.05rem;
  font-weight: 600;
}

.card-subtitle {
  font-size: 0.65rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.problem-desc {
  color: var(--text-secondary);
  font-size: 0.85rem;
  line-height: 1.5;
  white-space: pre-wrap;
}

.stats-card {
  margin-top: auto;
}

.chart-container {
  height: 180px;
}

/* Right Pane */
/* Right Pane Layout Fix */
.right-pane {
  background: var(--bg-app);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  height: 100%;
  overflow: hidden;
}

.editor-wrapper {
  display: flex;
  flex-direction: column;
  flex: 1 1 60%;
  min-height: 240px;
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  overflow: hidden;
  background: #04070b;
}

.code-area {
  flex: 1;
  display: flex;
}

#code-editor {
  width: 100%;
  height: 100%;
  background: transparent;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  border: none;
  padding: 0.85rem;
  outline: none;
  resize: none;
  line-height: 1.5;
  tab-size: 2;
  overflow-y: auto;
}

/* Console Scroll Fix */
.terminal-wrapper {
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  background: var(--bg-surface);
  flex: 0 0 180px;
  max-height: 220px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.terminal-content {
  padding: 0.85rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.5;
  overflow-y: auto;
  flex: 1;
}

.editor-header {
  height: 38px;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 0.75rem;
}

.tab {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.tab-indicator {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-blue);
}

.action-buttons {
  display: flex;
  gap: 6px;
}

.btn {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: 5px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.15s ease-in-out;
}

.btn-primary {
  background: var(--accent-blue);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-blue-hover); }

.btn-secondary {
  background: var(--accent-green);
  color: #fff;
}
.btn-secondary:hover { background: var(--accent-green-hover); }

.btn-subtle {
  background: transparent;
  color: var(--text-secondary);
  border-color: var(--border-subtle);
}
.btn-subtle:hover { color: var(--text-primary); border-color: var(--border-active); }

.hidden { display: none !important; }

.code-area {
  flex: 1;
}

#code-editor {
  width: 100%;
  height: 100%;
  min-height: 280px;
  background: transparent;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  border: none;
  padding: 0.85rem;
  outline: none;
  resize: none;
  line-height: 1.5;
  tab-size: 2;
}

/* Console */
.terminal-wrapper {
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  background: var(--bg-surface);
  min-height: 140px;
  display: flex;
  flex-direction: column;
}

.terminal-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 10px;
  background: var(--bg-surface-elevated);
  border-bottom: 1px solid var(--border-subtle);
}

.console-title {
  font-size: 0.65rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
  letter-spacing: 0.05em;
}

.status-indicator {
  font-size: 0.65rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
}

.status-pass { color: #3fb950; font-weight: 600; }
.status-fail { color: #f85149; font-weight: 600; }

.terminal-content {
  padding: 0.85rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.5;
  overflow-y: auto;
}

.console-idle { color: var(--text-muted); }
.console-pass { color: #3fb950; }
.console-fail { color: #f85149; }

.user-select-wrapper {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-subtle);
  padding: 2px 8px;
  border-radius: 6px;
}

.user-icon {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent-blue);
  font-weight: 600;
}
.hint-card {
  position: relative;
  background: var(--bg-surface-elevated);
}

.hint-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.btn-hint-toggle {
  background: transparent;
  border: 1px solid var(--border-active);
  color: var(--accent-blue);
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-hint-toggle:hover {
  background: rgba(47, 129, 247, 0.1);
}

.hint-body {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.4;
  font-family: var(--font-sans);
  transition: filter 0.2s ease, opacity 0.2s ease;
}

.hint-body.blur {
  filter: blur(4px);
  user-select: none;
  opacity: 0.6;
}
/* Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  backdrop-filter: blur(4px);
}

.modal-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-active);
  border-radius: 8px;
  width: 90%;
  max-width: 560px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.5);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.75rem 1rem;
  background: var(--bg-surface-elevated);
  border-bottom: 1px solid var(--border-subtle);
}

.modal-title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.btn-close {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-size: 1.2rem;
  cursor: pointer;
}
.btn-close:hover { color: var(--text-primary); }

.modal-warning {
  padding: 0.6rem 1rem;
  background: var(--accent-red-bg);
  color: var(--accent-red);
  font-size: 0.75rem;
  font-family: var(--font-mono);
  border-bottom: 1px solid var(--border-subtle);
}

.modal-code {
  padding: 1rem;
  background: #04070b;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.4;
  overflow-x: auto;
  max-height: 250px;
}

.modal-footer {
  padding: 0.75rem 1rem;
  background: var(--bg-surface-elevated);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: flex-end;
}