:root {
  --bg: #0f1419;
  --bg-elevated: #1a2129;
  --bg-hover: #252d38;
  --border: #2d3744;
  --text: #e7ecf2;
  --text-muted: #8b98a8;
  --accent: #4c9a9a;
  --accent-hover: #3b8888;
  --dir-color: #7eb8ff;
  --html-color: #7dd3a8;
  --sidebar-width: 320px;
  --header-height: 64px;
  --radius: 8px;
  --font: "Inter", system-ui, -apple-system, sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
}

body {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.header {
  height: var(--header-height);
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border);
  background: var(--bg-elevated);
  flex-shrink: 0;
}

.header__brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.header__logo {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border-radius: var(--radius);
  background: var(--accent);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
}

.header__title {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
}

.header__subtitle {
  margin: 2px 0 0;
  font-size: 12px;
  color: var(--text-muted);
}

.mode-switch {
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 4px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
}

.mode-switch__option {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 13px;
  cursor: pointer;
  user-select: none;
}

.mode-switch__option input {
  display: none;
}

.mode-switch__option:has(input:checked) {
  background: var(--accent);
  color: #fff;
}

.layout {
  flex: 1;
  display: flex;
  min-height: 0;
}

.sidebar {
  width: var(--sidebar-width);
  border-right: 1px solid var(--border);
  background: var(--bg-elevated);
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.sidebar__toolbar {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
}

.btn {
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  border-radius: 6px;
  padding: 6px 12px;
  font-size: 13px;
  cursor: pointer;
}

.btn:hover {
  background: var(--bg-hover);
}

.btn--ghost {
  width: 100%;
}

.tree {
  flex: 1;
  overflow: auto;
  padding: 8px 0;
}

.tree__loading,
.tree__error,
.tree__empty {
  padding: 16px;
  font-size: 13px;
  color: var(--text-muted);
}

.tree__error {
  color: #f87171;
}

.tree-node {
  user-select: none;
}

.tree-node__row {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px 4px 4px calc(8px + var(--depth, 0) * 16px);
  cursor: pointer;
  font-size: 13px;
  line-height: 1.4;
  border-radius: 4px;
  margin: 0 4px;
  position: relative;
}

.tree-node__row:hover {
  background: var(--bg-hover);
}

.tree-node__row--active {
  background: rgba(76, 154, 154, 0.2);
  outline: 1px solid var(--accent);
}

.tree-node__toggle {
  width: 16px;
  height: 16px;
  display: grid;
  place-items: center;
  flex-shrink: 0;
  color: var(--text-muted);
  font-size: 10px;
}

.tree-node__toggle--empty {
  visibility: hidden;
}

.tree-node__icon {
  flex-shrink: 0;
  font-size: 14px;
}

.tree-node__icon--dir {
  color: var(--dir-color);
}

.tree-node__icon--html {
  color: var(--html-color);
}

.tree-node__name {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.tree-node__menu {
  position: relative;
  flex-shrink: 0;
}

.tree-node__menu-btn {
  width: 24px;
  height: 24px;
  display: grid;
  place-items: center;
  border: none;
  border-radius: 4px;
  background: transparent;
  color: var(--text-muted);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s, background 0.15s, color 0.15s;
}

.tree-node__row:hover .tree-node__menu-btn,
.tree-node__menu-btn:focus-visible,
.tree-node__menu-btn--open {
  opacity: 1;
}

.tree-node__menu-btn:hover,
.tree-node__menu-btn--open {
  background: var(--bg);
  color: var(--text);
}

.tree-node__dropdown {
  position: absolute;
  top: calc(100% + 4px);
  right: 0;
  z-index: 20;
  min-width: 180px;
  padding: 4px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-elevated);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
}

.tree-node__dropdown[hidden] {
  display: none;
}

.tree-node__dropdown-item {
  display: block;
  width: 100%;
  padding: 8px 10px;
  border: none;
  border-radius: 6px;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: 13px;
  text-align: left;
  cursor: pointer;
}

.tree-node__dropdown-item:hover {
  background: var(--bg-hover);
}

.tree-node__children {
  display: none;
}

.tree-node--expanded > .tree-node__children {
  display: block;
}

.preview {
  flex: 1;
  position: relative;
  background: #fff;
  min-width: 0;
}

.preview__empty {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: var(--bg);
  color: var(--text-muted);
  font-size: 14px;
}

.preview__frame {
  width: 100%;
  height: 100%;
  border: none;
  display: block;
}

.preview__frame[hidden] {
  display: none;
}

.preview__empty[hidden] {
  display: none;
}

@media (max-width: 768px) {
  .layout {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    max-height: 40vh;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
}