:root{
      --bg: #f4f7fb;
      --surface: rgba(255,255,255,.78);
      --surface-strong: #ffffff;
      --text: #0f172a;
      --muted: #64748b;
      --border: rgba(148,163,184,.25);
      --primary: #4f46e5;
      --primary-2: #2563eb;
      --danger: #ef4444;
      --success: #16a34a;
      --shadow: 0 12px 35px rgba(15, 23, 42, 0.08);
      --shadow-soft: 0 8px 20px rgba(15, 23, 42, 0.06);
      --radius: 20px;
      --radius-sm: 14px;
      --transition: 220ms ease;
    }

    body.dark {
      --bg: #0b1220;
      --surface: rgba(15, 23, 42, .72);
      --surface-strong: #111827;
      --text: #e5e7eb;
      --muted: #94a3b8;
      --border: rgba(148,163,184,.16);
      --shadow: 0 16px 40px rgba(0,0,0,0.28);
      --shadow-soft: 0 8px 22px rgba(0,0,0,0.18);
    }

    * { box-sizing: border-box; }

    html, body {
      margin: 0;
      padding: 0;
      min-height: 100%;
      font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
      background:
        radial-gradient(circle at top left, rgba(79,70,229,.18), transparent 28%),
        radial-gradient(circle at bottom right, rgba(37,99,235,.14), transparent 28%),
        var(--bg);
      color: var(--text);
      transition: background var(--transition), color var(--transition);
    }

    a { color: inherit; text-decoration: none; }

    .app {
      max-width: 1180px;
      margin: 0 auto;
      padding: 24px 16px 36px;
    }

    .topbar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
      margin-bottom: 20px;
      flex-wrap: wrap;
    }

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

    .logo {
      width: 46px;
      height: 46px;
      border-radius: 16px;
      background: linear-gradient(135deg, var(--primary), var(--primary-2));
      box-shadow: var(--shadow-soft);
      display: grid;
      place-items: center;
      color: white;
      font-weight: 800;
      letter-spacing: .5px;
      user-select: none;
    }

    .brand h1 {
      font-size: clamp(1.1rem, 2vw, 1.45rem);
      margin: 0;
      line-height: 1.1;
    }

    .brand p {
      margin: 3px 0 0;
      color: var(--muted);
      font-size: .92rem;
    }

    .top-actions {
      display: flex;
      align-items: center;
      gap: 12px;
      flex-wrap: wrap;
    }

    .link-btn, .theme-btn {
      border: 1px solid var(--border);
      background: var(--surface);
      color: var(--text);
      padding: 11px 14px;
      border-radius: 999px;
      font-weight: 600;
      cursor: pointer;
      transition: transform var(--transition), background var(--transition), border-color var(--transition), box-shadow var(--transition);
      box-shadow: var(--shadow-soft);
      backdrop-filter: blur(12px);
    }

    .link-btn:hover, .theme-btn:hover, .btn:hover {
      transform: translateY(-1px);
      box-shadow: var(--shadow);
    }

    .link-btn:active, .theme-btn:active, .btn:active {
      transform: translateY(0);
    }

    .panel {
      background: var(--surface);
      border: 1px solid var(--border);
      box-shadow: var(--shadow);
      border-radius: var(--radius);
      backdrop-filter: blur(14px);
      overflow: hidden;
    }

    .main-grid {
      display: grid;
      grid-template-columns: 1.35fr .9fr;
      gap: 18px;
      align-items: start;
    }

    .editor-panel {
      padding: 20px;
    }

    .section-title {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      margin-bottom: 14px;
    }

    .section-title h2 {
      margin: 0;
      font-size: 1.05rem;
    }

    .section-title span {
      color: var(--muted);
      font-size: .92rem;
    }

    textarea {
      width: 100%;
      min-height: 260px;
      resize: vertical;
      border: 1px solid var(--border);
      border-radius: 18px;
      background: var(--surface-strong);
      color: var(--text);
      padding: 18px;
      font-size: 1rem;
      line-height: 1.6;
      outline: none;
      transition: border-color var(--transition), box-shadow var(--transition), background var(--transition), color var(--transition);
      box-shadow: inset 0 1px 0 rgba(255,255,255,.04);
    }

    textarea:focus {
      border-color: rgba(79,70,229,.7);
      box-shadow: 0 0 0 4px rgba(79,70,229,.12);
    }

    .stats {
      display: grid;
      grid-template-columns: repeat(3, minmax(0, 1fr));
      gap: 12px;
      margin-top: 14px;
    }

    .stat {
      background: var(--surface-strong);
      border: 1px solid var(--border);
      border-radius: 16px;
      padding: 14px;
      box-shadow: var(--shadow-soft);
    }

    .stat .label {
      font-size: .85rem;
      color: var(--muted);
      margin-bottom: 6px;
    }

    .stat .value {
      font-size: 1.4rem;
      font-weight: 800;
      letter-spacing: -.02em;
    }

    .controls {
      display: grid;
      gap: 14px;
      margin-top: 18px;
    }

    .btn-grid {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 12px;
    }

    .btn {
      border: none;
      border-radius: 16px;
      padding: 13px 14px;
      font-weight: 700;
      cursor: pointer;
      transition: transform var(--transition), filter var(--transition), background var(--transition), opacity var(--transition);
      box-shadow: var(--shadow-soft);
      color: white;
    }

    .btn.primary { background: linear-gradient(135deg, var(--primary), var(--primary-2)); }
    .btn.success { background: linear-gradient(135deg, #22c55e, #16a34a); }
    .btn.neutral { background: linear-gradient(135deg, #64748b, #475569); }
    .btn.ghost {
      background: var(--surface-strong);
      color: var(--text);
      border: 1px solid var(--border);
    }
    .btn.danger { background: linear-gradient(135deg, #f97316, var(--danger)); }

    .btn.full { width: 100%; }

    .btn-row {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 12px;
    }

    .actions-bottom {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 12px;
    }

    .history-panel {
      padding: 20px;
      position: sticky;
      top: 18px;
    }

    .history-list {
      display: grid;
      gap: 12px;
      max-height: 700px;
      overflow: auto;
      padding-right: 4px;
    }

    .history-item {
      background: var(--surface-strong);
      border: 1px solid var(--border);
      border-radius: 16px;
      padding: 14px;
      box-shadow: var(--shadow-soft);
      transition: transform var(--transition), border-color var(--transition);
    }

    .history-item:hover {
      transform: translateY(-1px);
      border-color: rgba(79,70,229,.25);
    }

    .history-meta {
      display: flex;
      justify-content: space-between;
      gap: 10px;
      align-items: center;
      margin-bottom: 10px;
      flex-wrap: wrap;
    }

    .history-time {
      font-size: .8rem;
      color: var(--muted);
    }

    .history-snippet {
      color: var(--text);
      font-size: .95rem;
      line-height: 1.45;
      word-break: break-word;
      margin-bottom: 12px;
      white-space: pre-wrap;
    }

    .history-actions {
      display: flex;
      gap: 10px;
      flex-wrap: wrap;
    }

    .mini-btn {
      border: 1px solid var(--border);
      background: var(--bg);
      color: var(--text);
      padding: 9px 12px;
      border-radius: 12px;
      cursor: pointer;
      font-weight: 700;
      transition: transform var(--transition), background var(--transition), border-color var(--transition);
    }

    .mini-btn:hover {
      transform: translateY(-1px);
      border-color: rgba(79,70,229,.25);
    }

    .mini-btn.edit { background: rgba(79,70,229,.12); }
    .mini-btn.delete { background: rgba(239,68,68,.12); }
    .mini-btn.copy { background: rgba(22,163,74,.12); }

    .empty-state {
      color: var(--muted);
      text-align: center;
      padding: 26px 12px;
      border: 1px dashed var(--border);
      border-radius: 16px;
      background: rgba(148,163,184,.06);
    }

    .toast {
      position: fixed;
      right: 18px;
      bottom: 18px;
      background: var(--surface-strong);
      color: var(--text);
      border: 1px solid var(--border);
      box-shadow: var(--shadow);
      padding: 12px 16px;
      border-radius: 14px;
      transform: translateY(20px);
      opacity: 0;
      pointer-events: none;
      transition: opacity var(--transition), transform var(--transition);
      z-index: 999;
      font-weight: 700;
    }

    .toast.show {
      opacity: 1;
      transform: translateY(0);
    }

    .badge {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 8px 12px;
      border-radius: 999px;
      background: rgba(79,70,229,.12);
      color: var(--primary);
      font-weight: 700;
      font-size: .88rem;
      border: 1px solid rgba(79,70,229,.18);
    }

    .divider {
      height: 1px;
      background: var(--border);
      margin: 18px 0;
    }

    .footer-hint {
      margin-top: 12px;
      color: var(--muted);
      font-size: .9rem;
    }

    @media (max-width: 980px) {
      .main-grid {
        grid-template-columns: 1fr;
      }
      .history-panel {
        position: static;
      }
      .history-list {
        max-height: none;
      }
    }

    @media (max-width: 640px) {
      .app { padding: 14px 12px 24px; }
      .editor-panel, .history-panel { padding: 16px; }
      .stats, .btn-grid, .btn-row, .actions-bottom {
        grid-template-columns: 1fr;
      }
      textarea {
        min-height: 220px;
        padding: 15px;
      }
      .topbar {
        align-items: flex-start;
      }
    }