.viewport-back-to-top {
  position: absolute;
  right: 18px;
  bottom: 18px;
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 50%;
  box-shadow: 0 4px 12px rgba(0,0,0,0.12);
  cursor: pointer;
  z-index: 20;
  transition: opacity .15s, transform .15s;
  opacity: 0;
  pointer-events: none;
}
body.dark-theme .viewport-back-to-top {
  background: var(--panel-alt);
  color: #fff;
  border-color: rgba(255,255,255,0.08);
  box-shadow: 0 4px 12px rgba(0,0,0,0.5);
}
.viewport-back-to-top.show {
  opacity: 1;
  pointer-events: auto;
}
.viewport-back-to-top:hover {
  background: var(--border-soft);
  transform: translateY(-2px);
}
.viewport-back-to-top svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}
/* compare css */
.stats-row {display: flex;align-items: center;gap: 14px;padding: 10px 12px;margin: 12px 0;justify-content: center;background: var(--panel);border: 1px solid var(--border-soft);border-radius: 10px;}
.stat {display: flex;align-items: baseline;gap: 6px;padding: 4px 10px;border-radius: 8px;background: var(--panel-alt);}
.stat-value {font-size: 13px;font-weight: 600;}
.stat-label {font-size: 11px;color:var(--text);}

.stat.add .stat-value { color: var(--diff-added-text); }
.stat.remove .stat-value { color: var(--diff-removed-text); }
.stat.match .stat-value { color: var(--primary); }
.stat.diff .stat-value { color: var(--diff-removed-text); }
.stat.move .stat-value { color: var(--diff-moved-text); }
.char-changed{padding:1px 3px;border-radius:3px;font-weight:500;}
.char-changed.diff-added{background-color:var(--diff-added-subword) !important;color:var(--diff-added-subword-text) !important;}
.char-changed.diff-removed{background-color:var(--diff-removed-subword) !important;color:var(--diff-removed-subword-text) !important;}

/* High-performance single scroll viewport styles */
.diff-scroll-viewport {
  max-height: 75vh;
  overflow: auto;
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  background: var(--panel);
  position: relative;
}
.diff-split-wrapper {
  display: flex;
  flex-direction: column;
  width: 100%;
  min-width: 700px;
}
.diff-split-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--panel);
  border-bottom: 2px solid var(--border-soft);
  display: flex;
  user-select: none;
}
.diff-split-hdr-cell {
  flex: 1;
  padding: 8px 12px;
  font-weight: bold;
  font-size: 13px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.diff-split-hdr-cell.left-hdr {
  border-right: 1px solid var(--border-soft);
}
.diff-split-row {
  display: flex;
  width: 100%;
  border-bottom: 1px solid rgba(0,0,0,.04);
  min-height: 1.5rem;
}
body.dark-theme .diff-split-row {
  border-bottom-color: rgba(255,255,255,.04);
}
.diff-split-row:hover {
  background: var(--bg-overlay-medium);
}
.diff-cell {
  flex: 1;
  display: flex;
  align-items: stretch;
  min-width: 0;
  overflow: hidden;
}
.diff-split-wrapper .diff-cell {
  width: 50%;
  max-width: 50%;
  flex: 0 0 50%;
}
.diff-cell.cell-left {
  border-right: 1px solid var(--border-soft);
}
.diff-cell.cell-void {
  background-image: repeating-linear-gradient(45deg, var(--border) 25%, transparent 25%, transparent 75%, var(--border) 75%, var(--border-soft));
  background-size: 8px 8px;
  opacity: 0.35;
}
.line-number {
  width: 44px;
  flex-shrink: 0;
  text-align: right;
  padding: 5px 8px 5px 4px;
  color: var(--muted-2);
  border-right: 1px solid var(--border-soft);
  font-size: 11px;
  line-height: 1.7;
  user-select: none;
  background: var(--panel-alt);
}
.line-sign {
  color: var(--muted-2);
  width: 1.5rem;
  user-select: none;
  -webkit-user-select: none;
  flex-shrink: 0;
  text-align: center;
  font-size: 10px;
  font-weight: 700;
  padding-top: 0.25rem;
  padding-bottom: 0.25rem;
  line-height: 2;
}
.diff-split-row.search-active {
  background-color: rgba(242, 204, 96, 0.12) !important;
  box-shadow: inset 0 0 0 1px rgba(242, 204, 96, 0.5);
}
.diff-code {
  font-size: 13px;
  display: block;
  word-break: break-all;
  padding: 5px 8px 5px 6px;
  flex: 1;
  min-width: 0;
  overflow-x: auto;
}
.diff-code::-webkit-scrollbar {
  height: 4px;
}
.diff-code::-webkit-scrollbar-track {
  background: transparent;
}
.diff-code::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 2px;
}
.diff-code::-webkit-scrollbar-thumb:hover {
  background: var(--muted-2);
}
.diff-code pre {
  font-size: 13px;
  line-height: 1.5;
  margin: 0;
}
.diff-added {
  background-color: var(--diff-added-bg) !important;
}
.diff-removed {
  background-color: var(--diff-removed-bg) !important;
}
.diff-moved {
  background-color: var(--diff-moved-bg) !important;
}
.diff-added .line-sign, .diff-added .diff-code, .diff-added .diff-code pre {
  color: var(--diff-added-text) !important;
}
.diff-removed .line-sign, .diff-removed .diff-code, .diff-removed .diff-code pre {
  color: var(--diff-removed-text) !important;
}
.diff-moved .line-sign, .diff-moved .diff-code, .diff-moved .diff-code pre {
  color: var(--diff-moved-text) !important;
}

.pd-cell-deleted {
  background-color: var(--diff-removed-bg) !important;
  border-right: 3px solid var(--diff-removed-text) !important;
}
.pd-cell-modified-left {
  background-color: rgba(207, 34, 46, 0.04) !important;
  border-right: 2px solid rgba(207, 34, 46, 0.53) !important;
}
body.dark-theme .pd-cell-modified-left {
  background-color: rgba(218, 54, 51, 0.06) !important;
  border-right: 2px solid rgba(218, 54, 51, 0.53) !important;
}
.pd-cell-deleted .line-sign, .pd-cell-deleted .diff-code, .pd-cell-deleted .diff-code pre,
.pd-cell-modified-left .line-sign, .pd-cell-modified-left .diff-code, .pd-cell-modified-left .diff-code pre {
  color: var(--diff-removed-text) !important;
}

.pd-cell-added {
  background-color: var(--diff-added-bg) !important;
  border-right: 3px solid var(--diff-added-text) !important;
}
.pd-cell-modified-right {
  background-color: rgba(46, 160, 67, 0.04) !important;
  border-right: 2px solid rgba(46, 160, 67, 0.53) !important;
}
body.dark-theme .pd-cell-modified-right {
  background-color: rgba(46, 160, 67, 0.06) !important;
  border-right: 2px solid rgba(46, 160, 67, 0.53) !important;
}
.pd-cell-added .line-sign, .pd-cell-added .diff-code, .pd-cell-added .diff-code pre,
.pd-cell-modified-right .line-sign, .pd-cell-modified-right .diff-code, .pd-cell-modified-right .diff-code pre {
  color: var(--diff-added-text) !important;
}

.pd-cell-moved {
  background-color: var(--diff-moved-bg) !important;
  border-right: 3px solid var(--diff-moved-text) !important;
}
.pd-cell-moved .line-sign, .pd-cell-moved .diff-code, .pd-cell-moved .diff-code pre {
  color: var(--diff-moved-text) !important;
}
.diff-empty {
  opacity: .45;
  background-color: var(--bg-overlay-medium);
}
.diff-container {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.diff-minimap-horizontal {
  border-radius: 6px;
  overflow: hidden;
  height: 44px;
  padding: 5px 8px;
  background: var(--panel-alt);
  border: 1px solid var(--border);
  cursor: pointer;
}
.diff-minimap-horizontal canvas {
  width: 100%;
  height: 100%;
  image-rendering: crisp-edges;
}

.minimap-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.minimap-title {
  font-size: 13px;
  color: var(--text);
}

.minimap-hint {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 13px;
  color:var(--muted);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}

.dot.added {
  background: var(--diff-added-text)
}

.dot.removed {
  background: var(--diff-removed-text);
}

.dot.moved {
  background: var(--diff-moved-text);
}

.click-hint {
  opacity: 0.8;
}

/* Layout toolbar styling */
.output-toolbar {
display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 15px;
  margin-bottom: 12px;
  gap: 12px;
  flex-wrap: wrap;
background: var(--panel);
  border: 1px solid var(--border-soft);
  padding: 10px 10px 10px 10px;
  border-radius: 6px;
}
.toggle-group {
  display: flex;
  align-items: center;
  gap: 15px;
  flex-wrap: wrap;
}
.toggle-group label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  font-size: 13px;
  user-select: none;
}
.toggle-group input[type="checkbox"] {
  width: 15px;
  height: 15px;
  accent-color: var(--primary);
  cursor: pointer;
}

.toggle-group input[type="checkbox"]:hover {
  filter: brightness(1.15);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 20%, transparent);
}
.btn-small {
display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 10px;
  font-size: 12px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 4px;
  cursor: pointer;
  transition: .15s;
}
.btn-small:not(.active):hover {
  background: var(--primary);
  color: #fff;
}
.btn-small.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
.btn-small svg {
  width:15px;
  height:15px;
  flex-shrink:0;
}

.sw {
  position: relative;
  display: flex;
  align-items: center;
}

.sw .si {
  position: absolute;
  left: 7px;
  width: 11px;
  height: 11px;
  color: var(--txt-muted);
  pointer-events: none;
}

.search-input {
font-size: 11px;
  color: var(--text);
  border: 1px solid var(--border);
  padding: 0 24px 0 24px;
  height: 26px;
  width: 160px;
  outline: none;
  background: var(--textarea-bg);
}

.search-input:focus {
  border-color: var(--primary);
}

.sc {
  position: absolute;
  right: 5px;
  background: none;
  border: none;
  color: var(--txt-muted);
  cursor: pointer;
  padding: 2px;
  display: flex;
  align-items: center;
  border-radius: 3px;
}

.sc:hover {
  background: rgba(0,0,0,.03);
}

.sc svg {
  width: 12px;
  height: 12px;
}

.pd-code-wrap {
  white-space: pre-wrap !important;
  word-break: break-all !important;
  word-wrap: break-word !important;
  overflow-x: hidden !important;
  display: block !important;
  width: 100% !important;
  max-width: 100% !important;
}
.pd-code-wrap pre {
  white-space: pre-wrap !important;
  word-break: break-all !important;
  word-wrap: break-word !important;
  display: block !important;
  width: 100% !important;
  max-width: 100% !important;
  overflow: hidden !important;
}
.pd-code-nowrap {
  white-space: pre !important;
  overflow-x: auto !important;
}
.pd-code-nowrap pre {
  white-space: pre !important;
}
textarea.drag-over {
  background: var(--bg-overlay-medium) !important;
  outline: 2px dashed var(--primary) !important;
  outline-offset: -4px !important;
}

.collapsed-banner-row {
  background: var(--panel-alt);
  border: 1px dashed var(--border-soft);
  padding: 10px;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  cursor: pointer;
  margin: 6px 0;
  border-radius: 6px;
  transition: .15s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  user-select: none;
}
.collapsed-banner-row:hover {
  background: var(--border-soft);
}

/* loading */
.diff-loader {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: 25px auto;
  max-width: 460px;
  padding: 24px;
  background: var(--panel);
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  box-shadow: var(--shadow);
  text-align: center;
  gap: 16px;
  contain: content;
}

.loader-title {
  font-weight: 600;
  font-size: 14px;
  color: var(--text);
}

.loader-subtitle {
  font-size: 12px;
  color: var(--muted);
  margin-top: 8px;
}

.loading-bar-outer {
  width: 100%;
  height: 6px;
  background: var(--panel-alt);
  border-radius: 3px;
  overflow: hidden;
  position: relative;
  contain: strict;
  margin-top: 16px;
}

.loading-bar-inner {
  position: absolute;
  inset: 0;
  width: 40%;
  border-radius: 3px;
  background: var(--primary);
  transform: translate3d(-140%, 0, 0);
  animation: progressAnimation 2s ease infinite;
  will-change: transform;
}

@keyframes progressAnimation {
  0% {
    transform: translate3d(-140%, 0, 0) scaleX(0.4);
  }

  50% {
    transform: translate3d(30%, 0, 0) scaleX(0.7);
  }

  100% {
    transform: translate3d(260%, 0, 0) scaleX(0.4);
  }
}

/* Accessibility + lower CPU */
@media (prefers-reduced-motion: reduce) {
  .loading-bar-inner {
    animation: none;
  }
}