/* ============================================================
   iSticker — Layout Styles
   Three-panel app layout: left sidebar, center canvas, right sidebar.
   Responsive behaviour for tablets and mobile.
   ============================================================ */

/* ============================================================
   APP SHELL
   ============================================================ */
.app {
  display: flex;
  flex-direction: column;
  height: 100dvh;
  width: 100dvw;
  overflow: hidden;
  background: var(--is-bg-app);
}

/* ============================================================
   HEADER
   ============================================================ */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--is-header-h);
  padding: 0 var(--is-sp-4);
  background: var(--is-bg-panel);
  border-bottom: 1px solid var(--is-border-subtle);
  flex-shrink: 0;
  z-index: var(--is-z-sticky);
  user-select: none;
}

.header-left {
  display: flex;
  align-items: center;
  gap: var(--is-sp-3);
  min-width: 0;
}

.header-right {
  display: flex;
  align-items: center;
  gap: var(--is-sp-1);
  flex-shrink: 0;
}

/* ============================================================
   MAIN — THREE-PANEL LAYOUT
   ============================================================ */
.app-main {
  display: flex;
  flex: 1;
  min-height: 0;           /* let flex children shrink */
  overflow: hidden;
}

/* ============================================================
   PANEL — Shared
   ============================================================ */
.panel {
  display: flex;
  flex-direction: column;
  background: var(--is-bg-panel);
  min-height: 0;
  overflow: hidden;
}

/* ---- Panel sections ---- */
.panel-section {
  padding: var(--is-sp-3) var(--is-sp-4);
  display: flex;
  flex-direction: column;
  gap: var(--is-sp-3);
  flex-shrink: 0;
}

.panel-section + .panel-section {
  border-top: 1px solid var(--is-border-subtle);
}

.panel-section--scroll {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  min-height: 0;
  /* Fade-out hint at bottom */
  mask-image: linear-gradient(
    to bottom,
    black 0%,
    black calc(100% - 24px),
    transparent 100%
  );
  -webkit-mask-image: linear-gradient(
    to bottom,
    black 0%,
    black calc(100% - 24px),
    transparent 100%
  );
  padding-bottom: var(--is-sp-8);
}

.panel-section--sticky {
  position: sticky;
  bottom: 0;
  background: var(--is-bg-panel);
  border-top: 1px solid var(--is-border-subtle);
  z-index: var(--is-z-sticky);
  margin-top: auto;
  padding: var(--is-sp-3) var(--is-sp-4);
}

.panel-title {
  font-size: var(--is-fs-sm);
  font-weight: var(--is-fw-semibold);
  color: var(--is-fg-primary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* ============================================================
   LEFT PANEL — Image Upload & List
   ============================================================ */
.panel--left {
  width: var(--is-panel-w);
  min-width: var(--is-panel-w);
  border-right: 1px solid var(--is-border-subtle);
  flex-shrink: 0;
}

/* ============================================================
   CENTER PANEL — Canvas Preview
   ============================================================ */
.panel--center {
  flex: 1;
  min-width: 0;
  background: var(--is-bg-canvas);
  position: relative;
}

/* ============================================================
   RIGHT PANEL — Settings
   ============================================================ */
.panel--right {
  width: var(--is-panel-w-lg);
  min-width: var(--is-panel-w-lg);
  border-left: 1px solid var(--is-border-subtle);
  flex-shrink: 0;
  overflow-y: auto;
  overflow-x: hidden;
}

/* ============================================================
   RESPONSIVE: Large Screens (>= 1440px)
   ============================================================ */
@media (min-width: 1440px) {
  :root {
    --is-panel-w:    300px;
    --is-panel-w-lg: 320px;
  }
}

/* ============================================================
   RESPONSIVE: Medium Screens (tablets, < 1024px)
   Collapse right panel into an overlay or make panels narrower.
   ============================================================ */
@media (max-width: 1024px) {
  :root {
    --is-panel-w:    240px;
    --is-panel-w-lg: 260px;
  }

  .app-header {
    padding: 0 var(--is-sp-3);
  }

  .panel-section {
    padding: var(--is-sp-2) var(--is-sp-3);
    gap: var(--is-sp-2);
  }

  .panel-section--sticky {
    padding: var(--is-sp-2) var(--is-sp-3);
  }
}

/* ============================================================
   RESPONSIVE: Small Screens (< 768px)
   Stack panels vertically, make it a single-column experience.
   ============================================================ */
@media (max-width: 768px) {
  .app-main {
    flex-direction: column;
  }

  .panel--left {
    width: 100%;
    min-width: 0;
    border-right: none;
    border-bottom: 1px solid var(--is-border-subtle);
    max-height: 30dvh;
  }

  .panel--left .upload-zone {
    padding: var(--is-sp-3) var(--is-sp-2);
  }

  .panel--left .upload-zone__content svg {
    width: 28px;
    height: 28px;
  }

  .panel--center {
    flex: 1;
    min-height: 30dvh;
  }

  .panel--right {
    width: 100%;
    min-width: 0;
    border-left: none;
    border-top: 1px solid var(--is-border-subtle);
    max-height: 40dvh;
  }

  /* Switch image grid to horizontal scroll on mobile */
  .image-list {
    grid-template-columns: repeat(auto-fill, minmax(48px, 1fr));
    gap: var(--is-sp-1);
  }

  /* Preset grid wraps tighter */
  .preset-grid {
    gap: var(--is-sp-1);
  }

  /* Smaller field rows */
  .field-row {
    gap: var(--is-sp-1);
  }

  /* Toast position */
  .toast-container {
    left: var(--is-sp-3);
    right: var(--is-sp-3);
    bottom: var(--is-sp-3);
  }

  .toast {
    max-width: 100%;
  }
}

/* ============================================================
   RESPONSIVE: Extra Small (< 480px)
   ============================================================ */
@media (max-width: 480px) {
  .app-header {
    padding: 0 var(--is-sp-2);
  }

  .header-left .badge {
    display: none;
  }

  .logo-text {
    font-size: var(--is-fs-base);
  }

  .panel-section {
    padding: var(--is-sp-2);
    gap: var(--is-sp-2);
  }

  .panel-section--sticky {
    padding: var(--is-sp-2);
  }

  .panel-title {
    font-size: var(--is-fs-xs);
  }

  /* Stacked size fields */
  .field-row {
    grid-template-columns: 1fr;
  }

  .canvas-toolbar {
    padding: var(--is-sp-1);
    gap: var(--is-sp-1);
  }

  .zoom-label {
    display: none;
  }

  .sheet-pagination {
    padding: var(--is-sp-1);
  }
}

/* ============================================================
   PRINT
   Hide UI chrome, show only the canvas content.
   ============================================================ */
@media print {
  .app-header,
  .panel--left,
  .panel--right,
  .canvas-toolbar,
  .sheet-pagination,
  .toast-container {
    display: none !important;
  }

  .app-main {
    display: block;
  }

  .panel--center {
    width: 100%;
    background: white;
  }

  .canvas-viewport {
    overflow: visible;
    background: white;
  }

  .canvas-wrapper canvas {
    box-shadow: none;
    background: none !important;
  }
}

/* ============================================================
   DARK-MODE OVERRIDES FOR LAYOUT (if needed)
   ============================================================ */
[data-theme="dark"] .panel--left,
[data-theme="dark"] .panel--right {
  border-color: var(--is-border-subtle);
}

[data-theme="dark"] .app-header {
  border-color: var(--is-border-subtle);
}

/* ============================================================
   TRANSITION FOR PANELS (for future collapsible support)
   ============================================================ */
.panel--left,
.panel--right {
  transition:
    width var(--is-dur-slow) var(--is-ease-out),
    min-width var(--is-dur-slow) var(--is-ease-out),
    max-height var(--is-dur-slow) var(--is-ease-out),
    opacity var(--is-dur-slow) var(--is-ease-out);
}

.panel--left.is-collapsed {
  width: 0;
  min-width: 0;
  opacity: 0;
  overflow: hidden;
  border-right: none;
  padding: 0;
}

.panel--right.is-collapsed {
  width: 0;
  min-width: 0;
  opacity: 0;
  overflow: hidden;
  border-left: none;
  padding: 0;
}

/* Collapsed section children should also hide */
.panel.is-collapsed .panel-section {
  padding: 0;
  overflow: hidden;
}