body { margin: 0; background-color: var(--color-background-tertiary); font-family: var(--font-sans); color: var(--color-text-primary); -webkit-font-smoothing: antialiased; }
  .container { padding: 3rem 1.5rem; max-width: 680px; margin: 0 auto; min-height: 100vh; }
  
  .main-title { text-align: center; font-size: 28px; font-weight: 800; letter-spacing: -0.5px; color: var(--color-text-primary); margin-top: 0; margin-bottom: 2.5rem; }
  
  .progress-bar { height: 8px; background: var(--color-background-secondary); border-radius: 99px; margin-bottom: 2rem; overflow: hidden; box-shadow: inset 0 1px 2px rgba(0,0,0,0.05); }
  .progress-fill { height: 100%; background: linear-gradient(90deg, #34d399, var(--primary-color)); border-radius: 99px; transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1); }
  
  .card { background: var(--color-background-primary); border: 1px solid var(--color-border-secondary); border-radius: var(--border-radius-xl); padding: 2rem; margin-bottom: 1.5rem; box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03); transition: box-shadow 0.3s ease; }
  .card:hover { box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.04); }
  
  textarea, input[type=text], input[type=email], input[type=password] { width: 100%; box-sizing: border-box; font-size: 15px; border: 1px solid var(--color-border-primary); border-radius: var(--border-radius-md); padding: 12px 16px; background: var(--color-background-primary); color: var(--color-text-primary); font-family: var(--font-sans); transition: all 0.2s ease; box-shadow: inset 0 1px 2px rgba(0,0,0,0.02); }
  textarea { resize: vertical; min-height: 100px; font-size: 16px; line-height: 1.5; }
  textarea:focus, input[type=text]:focus, input[type=email]:focus, input[type=password]:focus { outline: none; border-color: var(--primary-color); box-shadow: 0 0 0 3px rgba(29,158,117,0.2); }
  input[type=checkbox] { width: 18px; height: 18px; accent-color: var(--primary-color); cursor: pointer; flex-shrink: 0; margin-top: 4px; transition: transform 0.2s; }
  input[type=checkbox]:hover { transform: scale(1.1); }
  
  button { border: 1px solid var(--color-border-secondary); background: var(--color-background-primary); border-radius: var(--border-radius-md); padding: 10px 20px; font-size: 14px; font-weight: 600; color: var(--color-text-primary); cursor: pointer; transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1); white-space: nowrap; box-shadow: 0 1px 2px rgba(0,0,0,0.05); font-family: var(--font-sans); }
  button:hover { background: var(--color-background-secondary); transform: translateY(-2px); box-shadow: 0 4px 6px rgba(0,0,0,0.08); }
  button:active { transform: translateY(0); box-shadow: 0 1px 2px rgba(0,0,0,0.05); }
  button:disabled { opacity: 0.5; cursor: not-allowed; transform: none; box-shadow: none; }
  button.primary { background: var(--primary-color); border-color: var(--primary-color); color: #fff; box-shadow: 0 2px 4px rgba(29,158,117,0.2); }
  button.primary:hover { background: var(--primary-hover); border-color: var(--primary-hover); box-shadow: 0 6px 12px rgba(29,158,117,0.3); }
  button.primary:disabled { background: var(--color-background-secondary); border-color: var(--color-border-tertiary); color: var(--color-text-tertiary); box-shadow: none; }
  button.danger { border-color: #A32D2D; color: #A32D2D; }
  button.danger:hover { background: #A32D2D; color: #fff; box-shadow: 0 4px 8px rgba(163,45,45,0.2); }
  button.icon-btn { padding: 6px 10px; font-size: 14px; box-shadow: none; }
  button.icon-btn:hover { box-shadow: 0 2px 4px rgba(0,0,0,0.05); }
  .btn-row { display: flex; gap: 8px; margin-top: 1rem; flex-wrap: wrap; }
  
  @keyframes slideDown { from { opacity: 0; transform: translateY(-10px); } to { opacity: 1; transform: translateY(0); } }

  
  .tab-row { display: flex; margin-bottom: 2rem; background: var(--color-background-secondary); padding: 6px; border-radius: var(--border-radius-lg); gap: 4px; border: 1px solid var(--color-border-tertiary); overflow: hidden; box-shadow: inset 0 2px 4px rgba(0,0,0,0.02); }
  .tab { flex: 1; padding: 12px 4px; font-size: 15px; font-weight: 600; border: none; border-radius: var(--border-radius-md); text-align: center; background: transparent; cursor: pointer; color: var(--color-text-secondary); box-shadow: none; transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1); }
  .tab:hover { transform: translateY(-1px); color: var(--color-text-primary); background: transparent; }
  .tab.active { background: var(--color-background-primary); color: var(--color-text-primary); font-weight: 700; box-shadow: 0 4px 6px rgba(0,0,0,0.05), 0 1px 3px rgba(0,0,0,0.1); transform: none; }
  
  .add-row { display: flex; flex-direction: column; gap: 12px; }
  .add-label { font-size: 13px; font-weight: 600; color: var(--color-text-secondary); margin-bottom: 4px; }
  
  .empty-state { text-align: center; padding: 3rem 2rem; color: var(--color-text-tertiary); font-size: 15px; background: var(--color-background-secondary); border-radius: var(--border-radius-lg); border: 1px dashed var(--color-border-primary); }
  
  .select-bar { display: flex; align-items: center; gap: 8px; margin-bottom: 1rem; flex-wrap: wrap; background: var(--color-background-secondary); padding: 8px 12px; border-radius: var(--border-radius-md); }
  .select-count { font-size: 14px; font-weight: 600; color: var(--color-text-primary); margin-left: auto; }
  .sel-btn { font-size: 13px; padding: 6px 12px; border-radius: 99px; }
  .section-title { font-size: 14px; font-weight: 600; color: var(--color-text-secondary); margin: 0 0 1rem; text-transform: uppercase; letter-spacing: 0.5px; }
  .list-title-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 1rem; flex-wrap: wrap; }
  .list-title-row .section-title { margin: 0; }
  .sentence-page-topbar { display: flex; align-items: center; margin-bottom: 1rem; }
  .sentence-back-button { padding: 8px 12px; font-size: 13px; }
  .study-actions { display: flex; gap: 8px; flex-wrap: wrap; }
  .study-actions button { padding: 8px 12px; font-size: 13px; }

  .set-list { display: flex; flex-direction: column; gap: 12px; }
  .set-item { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 16px; border: 1px solid var(--color-border-secondary); border-radius: var(--border-radius-lg); background: var(--color-background-primary); cursor: pointer; transition: all 0.2s ease; }
  .set-item:hover { background: var(--color-background-secondary); transform: translateY(-1px); box-shadow: 0 6px 12px rgba(0,0,0,0.05); }
  .set-title { font-size: 18px; font-weight: 800; color: var(--color-text-primary); }
  .set-meta { font-size: 13px; color: var(--color-text-secondary); margin-top: 4px; }
  .set-actions { display: flex; gap: 6px; flex-shrink: 0; }
  .login-shell { min-height: 100vh; display: grid; grid-template-columns: 60% 40%; background: var(--color-background-tertiary); }