:root {
  --c-bg: #eef2f7;
  --c-surface: #ffffff;
  --c-border: #e1e6ee;
  --c-border-2: #ced6e0;
  --c-text: #1a2332;
  --c-muted: #6b7785;
  --c-brand: #0066ab;
  --c-brand-2: #12c3f4;
  --c-brand-dark: #003664;
  --c-danger: #d94343;
  --topbar-h: 56px;
  --sidebar-w: 360px;
  --radius: 8px;
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, .06);
  --shadow-md: 0 4px 14px rgba(16, 24, 40, .08);
  --shadow-lg: 0 12px 32px rgba(16, 24, 40, .12);
}

/* ── Top bar ───────────────────────────────────────── */
.topbar {
  position: sticky; top: 0; z-index: 20;
  height: var(--topbar-h);
  background: linear-gradient(90deg, #003664 0%, #0066ab 60%, #12c3f4 100%);
  color: #fff;
  display: flex; align-items: center; justify-content: space-between;
  gap: 8px;
  padding: 0 12px;
  box-shadow: var(--shadow-md);
}
.brand { display: flex; align-items: center; gap: 10px; min-width: 0; flex-shrink: 1; cursor: pointer; transition: opacity .15s ease; }
.brand:hover { opacity: 0.82; }
.brand-logo { height: 28px; width: auto; flex-shrink: 0; filter: brightness(0) invert(1); }
.brand-text { display: flex; flex-direction: row; align-items: baseline; gap: 6px; min-width: 0; }
.brand-text strong { font-size: 16px; font-weight: 700; letter-spacing: .2px; white-space: nowrap; }
.brand-text span { font-size: 12px; font-weight: 400; opacity: .8; white-space: nowrap; }
.topbar-right { display: flex; gap: 6px; align-items: center; flex-shrink: 0; }

/* ── Buttons ───────────────────────────────────────── */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  height: 36px; padding: 0 14px; border-radius: 8px;
  font-size: 13px; font-weight: 600; white-space: nowrap;
  border: 1px solid transparent; transition: all .15s ease;
}
.btn.primary { background: #ffffff; color: var(--c-brand-dark); }
.btn.primary:hover { background: #f1faff; }
.btn.ghost { background: rgba(255, 255, 255, .12); color: #fff; border-color: rgba(255, 255, 255, .25); }
.btn.ghost:hover { background: rgba(255, 255, 255, .22); }
.btn.soft {
  background: #f1f5f9;
  color: var(--c-brand-dark);
  border-color: var(--c-border-2);
}
.btn.soft:hover { background: #e6eff8; border-color: var(--c-brand); }
.btn.block { width: 100%; }
.btn.danger { color: var(--c-danger); border-color: #f5cccc; background: #fff5f5; }
.btn.danger:hover { background: #ffeaea; }
.btn svg { flex-shrink: 0; }
.btn, .acc-head, .topbar { user-select: none; -webkit-user-select: none; }
.topbar .btn .btn-label { padding-left: 4px; }

/* ── App layout ─────────────────────────────────────── */
.app {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  height: calc(100vh - var(--topbar-h));
}
body.sidebar-collapsed .app { grid-template-columns: 0 1fr; }
body.sidebar-collapsed .sidebar { display: none; }

/* ── Sidebar ────────────────────────────────────────── */
.sidebar {
  background: var(--c-surface);
  border-right: 1px solid var(--c-border);
  overflow-y: auto;
}
.sidebar::-webkit-scrollbar { width: 8px; }
.sidebar::-webkit-scrollbar-thumb { background: #cfd6e0; border-radius: 8px; }
.sidebar-inner { padding: 12px; }
#sidebar-form { display: flex; flex-direction: column; gap: 8px; }

/* Accordion */
.acc {
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  background: #fff;
  overflow: hidden;
}
.acc-head {
  display: flex; align-items: center; justify-content: space-between;
  width: 100%; padding: 10px 12px;
  font-weight: 600; font-size: 13px;
  background: linear-gradient(180deg, #f7fafd, #eff5fb);
  border-bottom: 1px solid transparent;
  text-align: left;
  color: var(--c-brand-dark);
}
.acc-head:hover { background: linear-gradient(180deg, #eef5fc, #e6eff8); }
.acc-title { display: inline-flex; align-items: center; gap: 8px; }
.acc-icon {
  display: inline-flex; align-items: center; justify-content: center;
  width: 24px; height: 24px;
  border-radius: 6px;
  background: var(--c-brand);
  color: #fff;
}
.acc-icon svg { width: 14px; height: 14px; }
.acc-right { display: inline-flex; align-items: center; gap: 10px; }
.acc-chev { transition: transform .2s ease; color: var(--c-brand); display: inline-flex; align-items: center; }
.acc.open .acc-chev { transform: rotate(180deg); }

/* Section visibility toggle (iOS-style pill) */
.acc-toggle {
  position: relative; display: inline-block;
  width: 30px; height: 17px;
  cursor: pointer;
}
.acc-toggle input {
  position: absolute; inset: 0;
  width: 100%; height: 100%;
  margin: 0; padding: 0;
  appearance: none; -webkit-appearance: none;
  cursor: pointer; z-index: 2;
}
.acc-toggle-track {
  position: absolute; inset: 0;
  background: #cbd5e0;
  border-radius: 999px;
  transition: background .15s;
}
.acc-toggle-thumb {
  position: absolute;
  top: 2px; left: 2px;
  width: 13px; height: 13px;
  background: #fff;
  border-radius: 50%;
  box-shadow: 0 1px 2px rgba(0,0,0,.25);
  transition: transform .15s;
}
.acc-toggle input:checked ~ .acc-toggle-track { background: var(--c-brand); }
.acc-toggle input:checked ~ .acc-toggle-track .acc-toggle-thumb { transform: translateX(13px); }
.acc-toggle input:focus-visible ~ .acc-toggle-track {
  box-shadow: 0 0 0 3px rgba(0, 102, 171, .25);
}
.acc.open .acc-head { border-bottom-color: var(--c-border); }
.acc-body { display: none; padding: 12px; flex-direction: column; gap: 10px; }
.acc.open .acc-body { display: flex; }

/* Field */
.field { display: flex; flex-direction: column; gap: 4px; }
.field-label { font-size: 11px; font-weight: 600; color: var(--c-muted); text-transform: uppercase; letter-spacing: .4px; }
.field input[type="text"],
.field input[type="email"],
.field input[type="number"],
.field textarea,
.field select {
  width: 100%; padding: 8px 10px;
  border: 1px solid var(--c-border-2);
  border-radius: 6px;
  background: #fff;
  font-size: 13px;
  transition: border-color .15s, box-shadow .15s;
}
.field input:focus, .field textarea:focus, .field select:focus {
  outline: none; border-color: var(--c-brand);
  box-shadow: 0 0 0 3px rgba(0, 102, 171, .12);
}
.field textarea { resize: vertical; min-height: 60px; font-family: inherit; }
.field select { background: #fff url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 8' fill='%230066ab'><path d='M6 8 0 0h12z'/></svg>") no-repeat right 10px center / 10px; appearance: none; padding-right: 28px; }

/* Color */
.color-wrap { display: flex; gap: 6px; align-items: center; }
.color-wrap input[type="color"] { width: 40px; height: 36px; padding: 2px; border: 1px solid var(--c-border-2); border-radius: 6px; background: #fff; cursor: pointer; }
.color-hex { flex: 1; font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: 12px !important; text-transform: uppercase; }

/* Zoom */
.zoom-wrap { display: grid; grid-template-columns: repeat(4, 1fr); gap: 4px; }
.zoom-btn {
  padding: 6px 4px; border-radius: 6px; font-size: 12px; font-weight: 600;
  background: #f1f5f9; border: 1px solid var(--c-border);
}
.zoom-btn.on { background: var(--c-brand); color: #fff; border-color: var(--c-brand); }

/* Avatar uploader */
.avatar-up { display: flex; gap: 10px; align-items: center; }
.avatar-up-preview {
  width: 64px; height: 64px; border-radius: 50%;
  background: #f0f4f8 center / cover no-repeat;
  border: 2px dashed var(--c-border-2);
  display: flex; align-items: center; justify-content: center;
  font-size: 22px; color: var(--c-muted);
}
.avatar-up-actions { display: flex; flex-direction: column; gap: 4px; flex: 1; }
.avatar-up-btn, .avatar-up-clear {
  font-size: 12px; padding: 6px 10px; border-radius: 6px;
  border: 1px solid var(--c-border-2); background: #fff;
}
.avatar-up-btn { color: var(--c-brand); border-color: var(--c-brand); }
.avatar-up-clear { color: var(--c-danger); }
.avatar-up-file { display: none; }

/* Array list */
.arr-list { display: flex; flex-direction: column; gap: 8px; }
.arr-item {
  border: 1px solid var(--c-border);
  border-radius: 6px;
  background: #fafcfe;
}
.arr-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 8px 10px; border-bottom: 1px solid var(--c-border);
  background: #fff;
}
.arr-head strong { font-size: 12px; color: var(--c-brand-dark); }
.arr-actions { display: flex; gap: 4px; }
.mini {
  width: 24px; height: 24px; border-radius: 4px;
  background: #fff; border: 1px solid var(--c-border-2);
  font-size: 11px; line-height: 1;
}
.mini:hover { background: #eef5fc; }
.mini.danger { color: var(--c-danger); border-color: #f5cccc; }
.mini.add { width: auto; padding: 4px 8px; color: var(--c-brand); border-color: var(--c-brand); }
.arr-editor { display: flex; flex-direction: column; gap: 8px; padding: 10px; }
.add-btn {
  display: block; width: 100%; padding: 8px;
  border-radius: 6px; border: 1px dashed var(--c-brand);
  color: var(--c-brand); background: #fff;
  font-weight: 600; font-size: 12px;
}
.add-btn:hover { background: #eef7fd; }

/* Bullets editor */
.bullets-edit { display: flex; flex-direction: column; gap: 6px; }
.bullet-row { display: flex; gap: 4px; align-items: stretch; }
.bullet-row textarea {
  flex: 1; padding: 6px 8px; font-size: 12px;
  border: 1px solid var(--c-border-2); border-radius: 6px; resize: vertical;
}

/* Level */
.level-edit { display: flex; gap: 4px; }
.lv-btn {
  width: 30px; height: 30px; border-radius: 6px;
  background: #f1f5f9; border: 1px solid var(--c-border);
  font-size: 12px; font-weight: 600;
}
.lv-btn.on { background: var(--c-brand); color: #fff; border-color: var(--c-brand); }

/* Switch row */
.switch-row { display: inline-flex; gap: 8px; align-items: center; font-size: 12px; cursor: pointer; }
.switch-row input[type="checkbox"] { width: 16px; height: 16px; accent-color: var(--c-brand); }

/* Preview area */
.preview {
  background:
    radial-gradient(1200px 600px at 20% -10%, rgba(18, 195, 244, .12), transparent 60%),
    radial-gradient(900px 500px at 90% 110%, rgba(0, 102, 171, .10), transparent 60%),
    var(--c-bg);
  overflow: auto;
  padding: 24px 16px;
}
.preview-scroll {
  display: flex; justify-content: center; align-items: flex-start; min-height: 100%;
}
.preview-zoom {
  transform-origin: top center;
  transition: transform .15s ease;
  position: relative;
}

/* Visual page-break indicator — sits exactly on the A4 boundary.
   Hidden during PDF capture via data-html2canvas-ignore. */
.page-divider {
  position: absolute;
  left: 0; right: 0;
  height: 0;
  border-top: 1px dashed rgba(0, 102, 171, .45);
  pointer-events: none;
  z-index: 5;
}
.page-divider::after {
  content: 'Trang ' attr(data-page);
  position: absolute;
  right: 12px; top: -10px;
  font-size: 10px; font-weight: 700;
  color: var(--c-brand);
  background: #fff;
  padding: 2px 9px;
  border: 1px solid rgba(0, 102, 171, .45);
  border-radius: 999px;
  white-space: nowrap;
}

/* ─── Responsive ──────────────────────────────────────
   Strategy: on narrow viewports, switch from 2-pane grid
   to a "tabs" model — body.mobile shows ONLY sidebar by
   default; pressing ☰ adds .show-preview to flip to A4.
   A4 page auto-fits viewport width via --fit-scale set
   by JS resize handler. */

@media (max-width: 980px) {
  .topbar { padding: 0 10px; }
  .btn { height: 34px; padding: 0 10px; font-size: 12px; }
  .app { grid-template-columns: 1fr; grid-template-rows: 1fr; }
  body.mobile .sidebar { display: block; border-right: 0; }
  body.mobile .preview { display: none; }
  body.mobile.show-preview .sidebar { display: none; }
  body.mobile.show-preview .preview { display: block; }
  body.mobile .preview { padding: 12px 8px; }
  body.mobile .preview-zoom {
    transform: scale(var(--fit-scale, 1)) !important;
    transform-origin: top center;
    /* compensate for scaled-down visual vs original layout size */
    margin-bottom: calc((var(--fit-scale, 1) - 1) * 297mm);
  }
  body.mobile .a4-page { box-shadow: 0 4px 18px rgba(16,24,40,.18); }

  /* Floating switch button when previewing */
  body.mobile .mobile-back {
    position: fixed; right: 12px; bottom: 12px; z-index: 30;
    width: 52px; height: 52px; border-radius: 50%;
    background: var(--c-brand); color: #fff;
    box-shadow: 0 6px 18px rgba(0,102,171,.4);
    display: none; align-items: center; justify-content: center;
    font-size: 22px; line-height: 1;
  }
  body.mobile.show-preview .mobile-back { display: flex; }
}

@media (max-width: 640px) {
  .brand-text span { display: none; }            /* "by MACLIFE" */
  .brand-text strong { font-size: 14px; }
  .brand-logo { height: 24px; }
  .btn-label { display: none; }                  /* show icon only */
  .btn { padding: 0 9px; min-width: 34px; }
}

@media (max-width: 420px) {
  .brand-text { display: none; }                 /* logo only */
  .topbar { gap: 4px; }
}