/* ========== BURNDOWN LAYOUT - Header, two-panel layout ========== */

/* ========== ASSEMBLY LINE HEADER ========== */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-lg);
  padding: var(--spacing-sm) var(--spacing-xl);
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-left {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
}

.header-right {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

/* Project title */
.header h1 {
  font-size: var(--font-lg);
  font-weight: 600;
  letter-spacing: var(--tracking-tight);
  color: var(--text-primary);
}

/* Mode toggle */
.mode-toggle {
  display: flex;
  gap: 1px;
  background: var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.mode-btn {
  padding: var(--spacing-xs) var(--spacing-md);
  background: var(--bg-tertiary);
  border: none;
  color: var(--text-secondary);
  font-size: var(--font-sm);
  font-weight: 500;
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.mode-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.mode-btn--active {
  background: var(--accent-subtle);
  color: var(--accent-bright);
}

/* ========== TWO-PANEL LAYOUT ========== */
.burndown-container {
  display: flex;
  height: calc(100vh - 52px);
  overflow: hidden;
}

/* ========== CHART PANEL ========== */
.chart-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  padding: var(--spacing-lg);
  gap: var(--spacing-lg);
}

/* ========== SPRINT SELECTOR ========== */
.sprint-selector {
  display: flex;
  gap: var(--spacing-xs);
  flex-wrap: wrap;
}

.sprint-btn {
  padding: var(--spacing-sm) var(--spacing-lg);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: var(--font-sm);
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
  transition: background var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast);
}

.sprint-btn:hover {
  background: var(--bg-hover);
  border-color: var(--border-strong);
  color: var(--text-primary);
}

.sprint-btn--active {
  background: var(--accent-subtle);
  border-color: var(--accent);
  color: var(--accent-bright);
}

.sprint-btn__status {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  margin-left: var(--spacing-xs);
}

.sprint-btn__status--planning {
  background: var(--text-muted);
}

.sprint-btn__status--active {
  background: var(--status-success);
  box-shadow: 0 0 4px var(--status-success);
}

.sprint-btn__status--completed {
  background: var(--accent);
}

/* ========== CHART WRAPPER ========== */
.chart-wrapper {
  flex: 1;
  position: relative;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  overflow: hidden;
  min-height: 300px;
}

.burndown-chart {
  width: 100%;
  height: 100%;
}

.chart-empty {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.chart-empty.hidden {
  display: none;
}

/* ========== CHART LEGEND ========== */
.chart-legend {
  display: flex;
  gap: var(--spacing-xl);
  justify-content: center;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: var(--font-sm);
  color: var(--text-secondary);
}

.legend-line {
  width: 24px;
  height: 2px;
  border-radius: 1px;
}

.legend-line--ideal {
  background: var(--text-muted);
  background: repeating-linear-gradient(
    90deg,
    var(--text-muted),
    var(--text-muted) 4px,
    transparent 4px,
    transparent 8px
  );
}

.legend-line--actual {
  background: var(--accent);
}

.legend-marker {
  width: 2px;
  height: 16px;
  border-radius: 1px;
}

.legend-marker--today {
  background: var(--status-warning);
}

/* ========== CHART ACTIONS ========== */
.chart-actions {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
}

/* ========== SIDEBAR PANEL ========== */
.sidebar-panel {
  flex: 0 0 280px;
  min-width: 240px;
  max-width: 320px;
  display: flex;
  flex-direction: column;
  background: var(--bg-secondary);
  border-left: 1px solid var(--border);
  overflow-y: auto;
}

.sidebar-section {
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--border);
}

.sidebar-section:last-child {
  border-bottom: none;
  flex: 1;
}

.sidebar-title {
  font-size: var(--font-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
  color: var(--text-muted);
  margin-bottom: var(--spacing-md);
}

/* ========== SPRINT DETAILS ========== */
.sprint-details {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.sprint-detail {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-xs) 0;
}

.sprint-detail__label {
  font-size: var(--font-sm);
  color: var(--text-muted);
}

.sprint-detail__value {
  font-size: var(--font-sm);
  font-weight: 500;
  color: var(--text-primary);
}

/* ========== HISTORY LIST ========== */
.history-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.history-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-sm);
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  font-size: var(--font-sm);
}

.history-item__name {
  color: var(--text-secondary);
}

.history-item__points {
  font-weight: 500;
  color: var(--accent);
}

.history-item--active {
  border: 1px solid var(--accent);
  background: var(--accent-subtle);
}

.history-item--active .history-item__name {
  color: var(--text-primary);
}

.history-empty {
  font-size: var(--font-sm);
  color: var(--text-muted);
  text-align: center;
  padding: var(--spacing-lg);
}

/* ========== VELOCITY SUMMARY ========== */
.velocity-summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md);
  margin-top: var(--spacing-md);
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
}

.velocity-label {
  font-size: var(--font-sm);
  color: var(--text-muted);
}

.velocity-value {
  font-size: var(--font-sm);
  font-weight: 600;
  color: var(--status-success);
}

/* ========== EMPTY STATES ========== */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-3xl);
  text-align: center;
}

.empty-state__icon {
  width: 48px;
  height: 48px;
  color: var(--text-muted);
  opacity: 0.5;
  margin-bottom: var(--spacing-lg);
}

.empty-state__title {
  font-size: var(--font-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

.empty-state__text {
  font-size: var(--font-sm);
  color: var(--text-muted);
  max-width: 300px;
  line-height: var(--leading-relaxed);
}

/* ========== RESPONSIVE ========== */
@media (max-width: 900px) {
  .header {
    flex-wrap: wrap;
  }

  .header-right {
    flex-wrap: wrap;
  }

  .burndown-container {
    flex-direction: column;
    height: auto;
  }

  .chart-panel {
    min-height: 60vh;
  }

  .sidebar-panel {
    flex: none;
    max-width: none;
    border-left: none;
    border-top: 1px solid var(--border);
  }
}

@media (max-width: 640px) {
  .header-left {
    flex-wrap: wrap;
    width: 100%;
  }

  .header-right {
    width: 100%;
    justify-content: flex-start;
  }

  .stat-item__label {
    display: none;
  }

  .action-group {
    display: none;
  }

  .sidebar-panel {
    flex: 0 0 auto;
    min-width: 0;
  }
}