/**
 * PJ_PIS - Layout & Viewport Management
 * Full-screen Flex Viewport, Splitter Containers, and Pane Isolation
 * 
 * Spec: SPEC-005 (REQ-021, D1, D3)
 */

/* ==========================================================================
   Full-screen Application Shell (Guarantees zero outer double scrollbars)
   ========================================================================== */

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

.app-header {
  height: 48px;
  min-height: 48px;
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-md);
  z-index: 10;
}

.app-body,
.app-main {
  flex: 1;
  display: flex;
  overflow: hidden;
  position: relative;
  width: 100%;
  height: calc(100vh - 48px);
}

/* ==========================================================================
   Splitter Layout & Pane Containers
   ========================================================================== */

.splitter-container {
  display: flex;
  width: 100%;
  height: 100%;
  overflow: hidden;
  position: relative;
}

.splitter-container.vertical {
  flex-direction: column;
}

.splitter-container.horizontal {
  flex-direction: row;
}

/* Isolated Scrolling Panes */
.pane {
  overflow-y: auto;
  overflow-x: hidden;
  position: relative;
  background-color: var(--color-surface);
}

.pane-left,
.pane-sidebar {
  width: 320px;
  min-width: 200px;
  max-width: 600px;
  background-color: var(--color-surface-2);
  border-right: 1px solid var(--color-border);
  overflow-y: auto;
  overflow-x: hidden;
}

.pane-right,
.pane-content {
  flex: 1;
  min-width: 300px;
  overflow-y: auto;
  overflow-x: auto;
  background-color: var(--color-bg);
  padding: var(--space-md);
}

.pane-top {
  height: 50%;
  min-height: 150px;
  overflow-y: auto;
  border-bottom: 1px solid var(--color-border);
}

.pane-bottom {
  flex: 1;
  min-height: 150px;
  overflow-y: auto;
}

/* ==========================================================================
   Draggable Splitter Gutters (Hardware-friendly styling)
   ========================================================================== */

.splitter-gutter {
  position: relative;
  background-color: transparent;
  z-index: 5;
  user-select: none;
  touch-action: none;
  transition: background-color var(--duration-fast) var(--ease-out);
}

.splitter-gutter::after {
  content: "";
  position: absolute;
  background-color: var(--color-border);
  transition: background-color var(--duration-fast) var(--ease-out);
}

/* Column (Vertical) Gutter */
.splitter-gutter-col {
  width: 8px;
  min-width: 8px;
  cursor: col-resize;
  margin: 0 -4px;
}

.splitter-gutter-col::after {
  top: 0;
  bottom: 0;
  left: 3px;
  width: 2px;
}

.splitter-gutter-col:hover::after,
.splitter-gutter-col.dragging::after {
  background-color: var(--color-primary);
}

/* Row (Horizontal) Gutter */
.splitter-gutter-row {
  height: 8px;
  min-height: 8px;
  cursor: row-resize;
  margin: -4px 0;
}

.splitter-gutter-row::after {
  left: 0;
  right: 0;
  top: 3px;
  height: 2px;
}

.splitter-gutter-row:hover::after,
.splitter-gutter-row.dragging::after {
  background-color: var(--color-primary);
}

/* ==========================================================================
   Dual-Breakpoint Responsive System
   Desktop: > 900px | Tablet / PDA: <= 768px
   ========================================================================== */

/* Desktop Ergonomic Multi-Column Mode */
@media (min-width: 901px) {
  .splitter-container {
    flex-direction: row;
  }

  .mobile-only {
    display: none !important;
  }
}

/* PDA / Tablet Compact Single-Column Mode */
@media (max-width: 768px) {
  .splitter-container {
    flex-direction: column !important;
  }

  .splitter-gutter-col {
    display: none;
  }

  .pane-left,
  .pane-sidebar {
    width: 100% !important;
    max-width: 100% !important;
    min-width: 100% !important;
    border-right: none;
    border-bottom: 1px solid var(--color-border);
    max-height: 40vh;
  }

  .pane-right,
  .pane-content {
    width: 100% !important;
    min-width: 100% !important;
    padding: var(--space-sm);
  }

  .desktop-only {
    display: none !important;
  }

  .mobile-only {
    display: flex !important;
  }

  .mobile-nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: transparent;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 18px;
    color: var(--color-text);
  }
}