:root {
  --bg: #f4f6fb;
  --panel: #ffffff;
  --panel-2: #fafbfe;
  --border: #e2e6ef;
  --text: #1f2733;
  --text-soft: #6b7488;
  --accent: #2f6df6;
  --accent-soft: #e8f0ff;
  --danger: #e23b3b;
  --danger-soft: #fdecec;
  --shadow: 0 6px 24px rgba(31, 39, 51, 0.12);
  --radius: 10px;
  --sidebar-w: 260px;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  -webkit-font-smoothing: antialiased;
}
.hidden { display: none !important; }
button { font-family: inherit; cursor: pointer; }

/* ---------- Login ---------- */
.login-overlay {
  position: fixed; inset: 0; z-index: 1000;
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, #2f6df6 0%, #6a4cf0 100%);
}
.login-box {
  background: var(--panel); padding: 32px 28px; border-radius: 16px;
  width: 320px; box-shadow: var(--shadow); text-align: center;
  display: flex; flex-direction: column; gap: 12px;
}
.login-logo { font-size: 48px; }
.login-box h1 { font-size: 20px; margin: 0; }
.login-sub { color: var(--text-soft); margin: 0 0 6px; font-size: 13px; }
.login-box input {
  padding: 11px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px;
}
.login-box button {
  background: var(--accent); color: #fff; border: 0; padding: 11px; border-radius: 8px; font-size: 15px;
}
.login-err { color: var(--danger); font-size: 13px; min-height: 16px; }

/* ---------- App shell ---------- */
.app { display: flex; flex-direction: column; height: 100vh; }

.topbar {
  display: flex; align-items: center; gap: 12px;
  padding: 10px 14px; background: var(--panel); border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.brand { font-weight: 700; font-size: 15px; white-space: nowrap; display: flex; align-items: center; gap: 6px; }
.menu-toggle { display: none; }
.icon-btn {
  background: transparent; border: 1px solid transparent; border-radius: 8px;
  width: 34px; height: 34px; font-size: 16px; color: var(--text-soft);
  display: inline-flex; align-items: center; justify-content: center;
}
.icon-btn:hover { background: var(--accent-soft); color: var(--accent); }

.breadcrumb {
  display: flex; align-items: center; gap: 2px; flex: 1 1 240px; min-width: 0;
  overflow-x: auto; white-space: nowrap; padding: 4px 0;
}
.crumb {
  background: transparent; border: 0; color: var(--text-soft); padding: 4px 6px;
  border-radius: 6px; font-size: 13px; white-space: nowrap;
}
.crumb:hover { background: var(--accent-soft); color: var(--accent); }
.crumb.active { color: var(--text); font-weight: 600; }
.crumb-sep { color: var(--text-soft); opacity: 0.5; }

.search-box {
  display: flex; align-items: center; background: var(--panel-2);
  border: 1px solid var(--border); border-radius: 8px; padding: 2px 4px 2px 10px;
}
.search-box input { border: 0; background: transparent; outline: none; padding: 7px 4px; width: 200px; font-size: 13px; }
.top-actions { display: flex; gap: 4px; }

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

/* ---------- Sidebar ---------- */
.sidebar {
  width: var(--sidebar-w); flex-shrink: 0; background: var(--panel);
  border-right: 1px solid var(--border); overflow-y: auto; padding: 10px 6px;
}
.sidebar-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 4px 8px 8px; color: var(--text-soft); font-size: 12px;
  text-transform: uppercase; letter-spacing: 0.04em;
}
.tree { font-size: 13px; }
.tree-node { user-select: none; }
.tree-row {
  display: flex; align-items: center; gap: 4px; padding: 5px 6px; border-radius: 6px; cursor: pointer;
}
.tree-row:hover { background: var(--accent-soft); }
.tree-row.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.tree-row .twist { width: 14px; text-align: center; color: var(--text-soft); font-size: 10px; }
.tree-row .ico { width: 18px; text-align: center; }
.tree-children { margin-left: 14px; border-left: 1px dashed var(--border); padding-left: 4px; }
.sidebar-backdrop { display: none; }

/* ---------- Main / toolbar ---------- */
.main { flex: 1; display: flex; flex-direction: column; min-width: 0; }
.toolbar {
  display: flex; align-items: center; gap: 8px; padding: 10px 14px;
  border-bottom: 1px solid var(--border); background: var(--panel-2); flex-wrap: wrap;
}
.btn {
  background: var(--panel); border: 1px solid var(--border); border-radius: 8px;
  padding: 7px 12px; font-size: 13px; color: var(--text);
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn.danger { color: var(--danger); border-color: var(--danger-soft); background: var(--danger-soft); }
.btn.danger:hover { background: var(--danger); color: #fff; }
.spacer { flex: 1; }
.status { color: var(--text-soft); font-size: 12px; }

.file-area { flex: 1; overflow-y: auto; padding: 14px; position: relative; }
.loading { color: var(--text-soft); padding: 20px; text-align: center; }
.empty { color: var(--text-soft); text-align: center; padding: 40px; }

/* ---------- Files grid ---------- */
.files.grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); gap: 10px;
}
.files.list { display: flex; flex-direction: column; gap: 2px; }

.file-item {
  position: relative; background: var(--panel); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 12px 10px; text-align: center; cursor: pointer;
  transition: transform 0.06s, box-shadow 0.06s, border-color 0.06s; user-select: none;
}
.files.grid .file-item:hover { box-shadow: var(--shadow); border-color: var(--accent); }
.file-item.selected { border-color: var(--accent); background: var(--accent-soft); }
.file-item .ficon { font-size: 34px; line-height: 1; margin-bottom: 8px; }
.file-item .fname {
  font-size: 13px; word-break: break-all; display: -webkit-box; -webkit-line-clamp: 2;
  -webkit-box-orient: vertical; overflow: hidden; min-height: 34px;
}
.file-item .fmeta { font-size: 11px; color: var(--text-soft); margin-top: 4px; }
.file-item .checkbox {
  position: absolute; top: 6px; left: 6px; width: 18px; height: 18px;
  border: 1px solid var(--border); border-radius: 4px; background: var(--panel);
  display: none; align-items: center; justify-content: center; font-size: 12px; color: #fff;
}
.file-item.selected .checkbox { display: flex; background: var(--accent); border-color: var(--accent); }

/* list view */
.files.list .file-item {
  display: flex; align-items: center; gap: 10px; text-align: left; padding: 8px 12px; border-radius: 8px;
}
.files.list .file-item .ficon { font-size: 22px; margin: 0; width: 26px; text-align: center; }
.files.list .file-item .fname { -webkit-line-clamp: 1; min-height: 0; flex: 1; }
.files.list .file-item .fmeta { margin: 0; width: 220px; text-align: right; }

/* ---------- Modals ---------- */
.modal-backdrop {
  position: fixed; inset: 0; background: rgba(20, 26, 38, 0.45); z-index: 500;
  display: flex; align-items: center; justify-content: center; padding: 16px;
}
.modal {
  background: var(--panel); border-radius: 14px; box-shadow: var(--shadow);
  width: 100%; max-width: 860px; max-height: 88vh; display: flex; flex-direction: column; overflow: hidden;
}
.modal.preview { max-width: 1000px; }
.modal.dialog { max-width: 420px; }
.modal-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 16px; border-bottom: 1px solid var(--border); font-weight: 600;
}
.modal-body { padding: 16px; overflow: auto; }
.modal-foot { padding: 12px 16px; border-top: 1px solid var(--border); display: flex; gap: 8px; justify-content: flex-end; }

.preview-meta { display: flex; flex-wrap: wrap; gap: 16px; color: var(--text-soft); font-size: 12px; margin-bottom: 12px; }
.preview-text { white-space: pre-wrap; word-break: break-word; font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace; font-size: 13px; line-height: 1.55; background: var(--panel-2); padding: 12px; border-radius: 8px; max-height: 60vh; overflow: auto; }
.preview-img { max-width: 100%; display: block; margin: 0 auto; }
.preview-nopreview { color: var(--text-soft); text-align: center; padding: 30px; }

.dialog input {
  width: 100%; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px; margin-top: 6px;
}
.dest-tree { max-height: 320px; overflow: auto; border: 1px solid var(--border); border-radius: 8px; padding: 8px; }
.dest-row { display: flex; align-items: center; gap: 6px; padding: 5px 6px; border-radius: 6px; cursor: pointer; }
.dest-row:hover { background: var(--accent-soft); }
.dest-row.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.dest-row .twist { width: 14px; text-align: center; color: var(--text-soft); font-size: 10px; }

/* ---------- Context menu ---------- */
.context-menu {
  position: fixed; z-index: 600; background: var(--panel); border: 1px solid var(--border);
  border-radius: 10px; box-shadow: var(--shadow); padding: 6px; min-width: 170px;
}
.context-menu .mi { padding: 8px 12px; border-radius: 6px; cursor: pointer; font-size: 13px; display: flex; gap: 8px; align-items: center; }
.context-menu .mi:hover { background: var(--accent-soft); color: var(--accent); }
.context-menu .mi.danger:hover { background: var(--danger-soft); color: var(--danger); }
.context-menu .sep { height: 1px; background: var(--border); margin: 5px 4px; }

/* ---------- Toast ---------- */
.toast {
  position: fixed; bottom: 22px; left: 50%; transform: translateX(-50%);
  background: #1f2733; color: #fff; padding: 11px 18px; border-radius: 10px; z-index: 700;
  box-shadow: var(--shadow); font-size: 13px; max-width: 90vw;
}
.toast.err { background: var(--danger); }

/* ---------- Responsive ---------- */
@media (max-width: 820px) {
  :root { --sidebar-w: 240px; }
  .menu-toggle { display: inline-flex; }
  .brand span { display: none; }
  .sidebar {
    position: fixed; top: 0; left: 0; bottom: 0; z-index: 400; transform: translateX(-100%);
    transition: transform 0.2s ease; box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }
  .sidebar-backdrop.show { display: block; position: fixed; inset: 0; background: rgba(0,0,0,0.3); z-index: 390; }
  .search-box input { width: 130px; }
  .files.grid { grid-template-columns: repeat(auto-fill, minmax(96px, 1fr)); }
  .files.list .file-item .fmeta { width: 110px; }
  .breadcrumb { order: 3; flex-basis: 100%; }
}
@media (max-width: 480px) {
  .toolbar .btn { padding: 7px 9px; font-size: 12px; }
  .topbar { gap: 8px; padding: 8px 10px; }
}