*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --bg: #ffffff;
  --surface: #f5f5f8;
  --sidebar: #f0f0f5;
  --text: #1e1e2e;
  --muted: #6c6c82;
  --border: #d0d0dd;
  --accent: #7c3aed;
  --accent-hover: #6d28d9;
  --danger: #dc2626;
  --font: 'Inter', sans-serif;
  --mono: 'Cascadia Code','Fira Code','JetBrains Mono',monospace;
}

html, body { height: 100%; font-family: var(--font); background: var(--bg); color: var(--text); font-size: 14px; }
a { color: var(--accent); text-decoration: none; }
::selection { background: rgba(124,58,237,.15); }
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--muted); }

/* Login */
.login-body { display: flex; align-items: center; justify-content: center; }
.login-box {
  background: var(--surface); padding: 2rem; border-radius: 8px;
  width: 320px; border: 1px solid var(--border); box-shadow: 0 2px 12px rgba(0,0,0,.06);
}
.login-box h1 { margin-bottom: 1.5rem; font-weight: 700; font-size: 1.5rem; color: var(--accent); letter-spacing: .02em; }
.login-box input, .login-box button {
  display: block; width: 100%; margin-bottom: .75rem;
  padding: .6rem .8rem; border-radius: 4px; border: 1px solid var(--border);
  background: var(--bg); color: var(--text); font-size: .9rem;
}
.login-box input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 2px rgba(124,58,237,.12); }
.login-box button { background: var(--accent); color: #fff; font-weight: 600; border: none; cursor: pointer; transition: background .15s; }
.login-box button:hover { background: var(--accent-hover); }
.error { color: var(--danger); font-size: .85rem; }
.hidden { display: none !important; }

/* App layout */
.app { display: flex; height: 100vh; }
#sidebar {
  width: 200px; min-width: 200px; background: var(--sidebar);
  border-right: 1px solid var(--border); display: flex; flex-direction: column;
  overflow: hidden; position: relative; transition: width .2s;
}
#sidebar.collapsed {
  width: 32px !important; min-width: 32px !important;
}
#sidebar.collapsed > * { display: none; }
#sidebar.collapsed #sidebar-header { display: flex; }
#sidebar.collapsed #sidebar-header span { display: none; }
#sidebar.collapsed #sidebar-header::after { content: 'f'; }
#sidebar-resizer {
  position: absolute; top: 0; right: 0; bottom: 0; width: 4px;
  cursor: col-resize; z-index: 10; background: transparent;
  transition: background .15s;
}
#sidebar-resizer:hover,
#sidebar-resizer.resizing {
  background: var(--accent);
}
#sidebar-header {
  padding: .75rem 1rem; border-bottom: 1px solid var(--border);
  display: flex; justify-content: space-between; align-items: center;
  font-weight: 700; font-size: .9rem; color: var(--accent); letter-spacing: .02em;
  cursor: pointer; user-select: none;
}
#sidebar-actions {
  padding: .5rem; border-top: 1px solid var(--border);
  display: flex; gap: 4px; flex-wrap: wrap;
}
#sidebar-actions button {
  flex: 1; padding: .35rem .5rem; border: 1px solid var(--border);
  border-radius: 4px; background: var(--surface); color: var(--text);
  font-size: .8rem; cursor: pointer; white-space: nowrap; transition: border-color .15s, color .15s;
}
#sidebar-actions button:hover { border-color: var(--accent); color: var(--accent); }
#sidebar-actions button.danger:hover { border-color: var(--danger); color: var(--danger); }
#tree-wrap { flex: 1; overflow-y: auto; padding: .25rem 0; }

/* Tree */
.tree ul { list-style: none; padding-left: 1.1rem; }
.tree > ul { padding-left: 0; }
.tree li { position: relative; }
.tree .entry {
  display: flex; align-items: center; padding: 3px 8px; cursor: pointer;
  border-radius: 3px; font-size: .85rem; gap: 4px; user-select: none;
}
.tree .entry:hover { background: rgba(124,58,237,.06); }
.tree .entry.active { background: rgba(124,58,237,.1); color: var(--accent); }
.tree .entry .icon { width: 16px; text-align: center; flex-shrink: 0; font-size: .7rem; color: var(--muted); }
.tree .children { display: none; }
.tree .children.open { display: block; }
.tree .entry .name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* Main */
#main { flex: 1; display: flex; flex-direction: column; min-width: 0; }
#editor-bar {
  padding: .5rem 1rem; border-bottom: 1px solid var(--border);
  display: flex; align-items: center; gap: .75rem; min-height: 40px;
  background: var(--surface);
}
#editor-bar .file-path {
  flex: 1; font-size: .85rem; color: var(--muted);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
#btn-save {
  padding: .35rem .9rem; border: none; border-radius: 4px;
  background: var(--accent); color: #fff; font-weight: 600;
  font-size: .8rem; cursor: pointer; transition: background .15s;
}
#btn-save:hover { background: var(--accent-hover); }
#btn-save:disabled { opacity: .5; cursor: not-allowed; }
#editor-wrap { flex: 1; overflow: hidden; display: flex; }