/* Fluent Design System - Light/Dark Theme */
:root {
  /* Safe defaults (Light) */
  --bg-color: #f3f3f3;
  --surface-color: #ffffff;
  --border-color: #e5e5e5;
  --text-primary: #1b1b1b;
  --text-secondary: #5d5d5d;
  --accent-color: #0067c0;
  --accent-hover: #005a9e;
  --accent-text: #ffffff;
  --focus-border: #1b1b1b;
  --item-hover: #fbfbfb;
  --item-active: #f0f0f0;
  --folder-hover: rgba(0, 0, 0, 0.04);
  --shadow-card: 0 4px 8px rgba(0, 0, 0, 0.08); /* Elevated 2 */

  --font-family: "Segoe UI Variable", "Segoe UI", system-ui, sans-serif;
  --sidebar-width: 320px;
  --sidebar-bg: rgba(243, 243, 243, 0.85);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #202020;
    --sidebar-bg: rgba(32, 32, 32, 0.7);
    --surface-color: #2c2c2c;
    --border-color: #3b3b3b;
    --text-primary: #ffffff;
    --text-secondary: #d0d0d0;
    --accent-color: #4cc2ff;
    --accent-hover: #4cc2ff;
    --accent-text: #000000;
    --focus-border: #ffffff;
    --item-hover: #383838;
    --item-active: #323232;
    --folder-hover: rgba(255, 255, 255, 0.04);
    --shadow-card: 0 4px 8px rgba(0, 0, 0, 0.3);
  }
}

* {
  box-sizing: border-box;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-primary);
  height: 100vh;
  overflow: hidden;
  user-select: none;
}

/* Layout */
.app-container {
  display: flex;
  height: 100%;
  width: 100%;
  background-image: radial-gradient(
    circle at 50% 0%,
    rgba(255, 255, 255, 0.05) 0%,
    transparent 70%
  );
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  max-width: 100vw;
  background-color: var(--sidebar-bg); /* Translucent */
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  transition: width 0.05s ease-out;
  box-shadow: var(--shadow-card);
  z-index: 10;
  position: relative;
}

.resize-handle {
  width: 5px;
  height: 100%;
  cursor: col-resize;
  background-color: transparent;
  transition: background-color 0.2s;
  flex-shrink: 0;
  z-index: 20;
  margin-left: -2px;
}

.resize-handle:hover,
.resize-handle.active {
  background-color: var(--accent-color);
}

.empty-space {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  font-size: 24px;
  font-weight: 300;
  opacity: 0.5;
  pointer-events: none;
  text-align: center;
  padding: 20px;
  font-family: "Segoe UI Display", var(--font-family);
  background: radial-gradient(
    circle at 50% 50%,
    var(--surface-color) 0%,
    transparent 100%
  );
}

.empty-space svg {
  width: 64px;
  height: 64px;
  margin-bottom: 16px;
  opacity: 0.8;
}

.sidebar-header {
  padding: 16px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: transparent; /* Match sidebar */
}

.app-title {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
}

.header-controls {
  display: flex;
  gap: 8px;
}

.fluent-btn-icon {
  background: transparent;
  border: none;
  color: var(--text-primary);
  border-radius: 4px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background 0.1s;
}

.fluent-btn-icon:hover {
  background-color: rgba(0, 0, 0, 0.05);
}

/* Enhanced Search Box */
.search-box {
  padding: 0 16px 12px 16px;
  position: relative;
}

.search-icon {
  position: absolute;
  left: 28px;
  top: 50%;
  transform: translateY(-80%); /* Adjusted for padding alignment */
  color: var(--text-secondary);
  pointer-events: none;
  width: 14px;
  height: 14px;
}

#search-input {
  width: 100%;
  padding: 8px 12px 8px 36px; /* Space for icon */
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background-color: var(--surface-color);
  color: var(--text-primary);
  font-size: 14px;
  outline: none;
  border-bottom: 2px solid transparent;
  transition:
    border-bottom-color 0.2s,
    box-shadow 0.2s;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.02);
}

#search-input:focus {
  border-bottom-color: var(--accent-color);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.bookmark-list {
  flex: 1;
  overflow-y: overlay;
  overflow-x: hidden;
  padding: 0 12px;
  scroll-padding-top: 8px;
}

/* Scrollbar */
.bookmark-list::-webkit-scrollbar {
  width: 6px;
}
.bookmark-list::-webkit-scrollbar-track {
  background: transparent;
}
.bookmark-list::-webkit-scrollbar-thumb {
  background-color: rgba(128, 128, 128, 0.3);
  border-radius: 10px;
  border: 2px solid transparent;
  background-clip: content-box;
}
.bookmark-list::-webkit-scrollbar-thumb:hover {
  background-color: rgba(128, 128, 128, 0.5);
}

/* --- Tree View Styling --- */

/* Folder Items */
.tree-folder {
  margin-bottom: 2px;
}

.tree-folder-header {
  display: flex;
  align-items: center;
  padding: 8px 12px;
  cursor: pointer;
  border-radius: 4px;
  color: var(--text-primary);
  font-size: 13px;
  font-weight: 600;
  transition: background 0.1s;
}

.tree-folder-header:hover {
  background-color: var(--folder-hover);
}

.tree-toggle-icon {
  width: 16px;
  height: 16px;
  margin-right: 8px;
  transition: transform 0.2s ease;
  flex-shrink: 0;
  color: var(--text-secondary);
}

.tree-folder.expanded > .tree-folder-header > .tree-toggle-icon {
  transform: rotate(90deg);
}

.tree-folder-children {
  margin-left: 20px; /* Indentation */
  border-left: 1px solid var(--border-color); /* Guide line */
  overflow: hidden; /* Important for grid animation */
  min-height: 0;
}

.tree-folder-anim-wrapper {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.25s cubic-bezier(0.2, 0, 0.2, 1);
}

.tree-folder.expanded > .tree-folder-anim-wrapper {
  grid-template-rows: 1fr;
}

/* Bookmark Items (Leaf) */
.bookmark-item {
  padding: 10px 14px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
  display: flex;
  align-items: flex-start;
  margin-bottom: 6px;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;

  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
  transition:
    transform 0.1s,
    box-shadow 0.1s;

  opacity: 0;
  animation: slideIn 0.3s cubic-bezier(0.25, 0.1, 0.25, 1) forwards;
}

.bookmark-item:hover,
.tree-folder-header:hover {
  background-color: var(--item-hover);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  transform: translateY(-1px);
  z-index: 2;
}

.bookmark-item:active {
  transform: translateY(0) scale(0.98);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.bookmark-item.selected,
.tree-folder-header.selected {
  background-color: var(--item-active);
  border-color: var(--accent-color);
  position: relative;
  box-shadow: 0 0 0 1px var(--accent-color) inset;
  z-index: 3;
}

.bookmark-item.selected::before,
.tree-folder-header.selected::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 10px;
  bottom: 10px;
  width: 4px;
  background-color: var(--accent-color);
  border-radius: 2px;
  z-index: 1;
}

.bookmark-icon {
  width: 16px;
  height: 16px;
  margin-right: 12px;
  flex-shrink: 0;
  border-radius: 2px;
}

/* Text & Mask */
.bookmark-text-mask {
  flex: 1;
  overflow: hidden;
  position: relative;
  white-space: nowrap;
  mask-image: linear-gradient(to right, black 90%, transparent 100%);
  -webkit-mask-image: linear-gradient(to right, black 90%, transparent 100%);
}

.bookmark-text-inner {
  display: inline-block;
}

.bookmark-item.can-scroll .bookmark-text-inner {
  animation: marquee var(--marquee-duration) linear 0.5s infinite;
}

/* Highlight */
.highlight-match {
  font-weight: 700;
  color: var(--accent-color);
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-decoration-color: rgba(var(--accent-color), 0.3);
}

/* Animations */
@keyframes marquee {
  0%,
  10% {
    transform: translateX(0);
  }
  100% {
    transform: translateX(var(--marquee-dist));
  }
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(-5px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* Toast */
.toast-container {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background-color: #333;
  color: white;
  padding: 10px 20px;
  border-radius: 24px;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
  font-size: 13px;
  font-weight: 500;
  opacity: 0;
  pointer-events: none;
  transition:
    opacity 0.3s,
    transform 0.3s;
  z-index: 1000;
}

.toast-container.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* Drag & Drop Overlay */
.drag-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 103, 192, 0.1);
  border: 3px dashed var(--accent-color);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.2s;
  backdrop-filter: blur(2px);
}

.drag-overlay.active {
  opacity: 1;
}

.drag-message {
  font-size: 24px;
  font-weight: 600;
  color: var(--accent-color);
  background: var(--surface-color);
  padding: 20px 40px;
  border-radius: 12px;
  box-shadow: var(--shadow-card);
}

.bookmark-meta {
  font-size: 11px;
  color: var(--text-secondary);
  margin-top: 2px;
  display: flex;
  align-items: center;
  opacity: 0.8;
}

.folder-icon-svg {
  width: 12px;
  height: 12px;
  margin-right: 4px;
  opacity: 0.7;
  flex-shrink: 0;
}

.bookmark-content {
  flex: 1;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

:focus-visible {
  outline: 2px solid var(--focus-border);
  outline-offset: 2px;
}