* {
      margin: 0;
      padding: 0;
      box-sizing: border-box
    }

    :root {
      --blue1: #4A7FE8;
      --blue2: #6B9BFF;
      --blue3: #8AB4FF;
      --blue-light: #EEF3FF;
      --blue-mid: #C8D9FF;
      --blue-glass: rgba(74, 127, 232, 0.12);
      --white-glass: rgba(255, 255, 255, 0.85);
      --text-dark: #1A2B5E;
      --text-mid: #4A5E8A;
      --text-soft: #7A8EB8;
      --bg: #EDF2FF;
      --radius: 20px;
      --radius-sm: 14px;
      --radius-xs: 10px;
      --shadow-premium: 0 10px 30px rgba(74, 127, 232, 0.08);
      --green: #5DCA8C;
      --green-dark: #1A6B40;
      --red: #FF6B6B;
      --red-dark: #8B1A1A;
    }

    @media (prefers-color-scheme: dark) {
      :root {
        --bg: #0F172A;
        --blue-light: #1E293B;
        --blue-mid: #334155;
        --blue-glass: rgba(74, 127, 232, 0.2);
        --white-glass: rgba(30, 41, 59, 0.75);
        --text-dark: #F8FAFC;
        --text-mid: #CBD5E1;
        --text-soft: #94A3B8;
        --shadow-premium: 0 10px 30px rgba(0, 0, 0, 0.35);
      }

      .bg-wrap {
        background: var(--bg) !important;
      }

      .btn-secondary {
        border: 1px solid var(--blue-mid) !important;
        color: var(--text-dark) !important;
        background: rgba(30, 41, 59, 0.5) !important;
      }

      .btn-secondary:hover {
        background: var(--blue-mid) !important;
      }

      .kbd {
        border: 1px solid var(--blue-mid) !important;
        color: var(--text-mid) !important;
        background: rgba(30, 41, 59, 0.5) !important;
      }

      .add-card-area {
        border-color: var(--blue-mid) !important;
      }

      .add-card-area:hover {
        border-color: var(--blue1) !important;
        background: var(--blue-light) !important;
      }

      .session-card-box .s-card-back {
        background: linear-gradient(135deg, #1E293B 0%, #0F172A 100%) !important;
      }

      .vocab-card {
        border: 1px solid rgba(255, 255, 255, 0.08) !important;
      }

      .weak-word-item {
        background: rgba(30, 41, 59, 0.4) !important;
        border: 1px solid var(--blue-mid) !important;
      }
    }

    /* ─── BRIGHT THEME ─── */
    body.theme-bright {
      --bg: #FFFFFF;
      --blue-light: #F0F7FF;
      --blue-mid: #D0E5FF;
      --white-glass: rgba(255, 255, 255, 0.95);
      --blue-glass: rgba(74, 127, 232, 0.2);
      --text-dark: #000000;
      --text-mid: #2A4070;
      --text-soft: #5A70A0;
    }

    body.theme-bright .bg-wrap {
      background: var(--bg) !important;
    }

    body.theme-bright .sidebar-section {
      background: #FFFFFF;
      border: 1.5px solid var(--blue-mid);
    }

    html,
    body {
      font-family: 'Manrope', sans-serif;
      background: var(--bg);
      min-height: 100vh;
      color: var(--text-dark);
      overflow-x: hidden;
    }

    /* ─── BACKGROUND ─── */
    .bg-wrap {
      position: fixed;
      inset: 0;
      z-index: 0;
      background: var(--bg);
    }

    /* ─── LAYOUT ─── */
    .app {
      position: relative;
      z-index: 1;
      max-width: 1100px;
      margin: 0 auto;
      padding: 24px 24px 40px;
    }

    /* ─── NAV ─── */
    nav {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 14px 24px;
      background: var(--white-glass);
      backdrop-filter: blur(24px);
      -webkit-backdrop-filter: blur(24px);
      border-radius: var(--radius);
      border: 1px solid rgba(255, 255, 255, 0.92);
      margin-bottom: 32px;
      box-shadow: var(--shadow-premium);
    }

    .logo {
      display: flex;
      align-items: center;
      gap: 11px;
      cursor: pointer;
    }

    .logo-icon {
      width: 36px;
      height: 36px;
    }

    .logo-icon svg {
      width: 100%;
      height: 100%;
    }

    .logo-name {
      font-size: 17px;
      font-weight: 700;
      color: var(--text-dark);
      letter-spacing: -.3px;
    }

    .logo-name span {
      color: var(--blue1);
    }

    .nav-links {
      display: flex;
      gap: 6px;
    }

    .nav-link {
      padding: 8px 16px;
      border-radius: var(--radius-xs);
      font-size: 13.5px;
      font-weight: 600;
      color: var(--text-mid);
      cursor: pointer;
      transition: all .2s ease;
      border: none;
      background: none;
      font-family: inherit;
    }

    .nav-link:hover {
      background: var(--blue-light);
      color: var(--blue1);
    }

    .nav-link.active {
      background: var(--blue1);
      color: #fff;
    }

    /* ─── SPA TAB CONTAINER ─── */
    .tab-content {
      display: none;
      animation: ws-fade-in 0.35s ease;
    }

    .tab-content.active {
      display: block;
    }

    @keyframes ws-fade-in {
      from {
        opacity: 0;
        transform: translateY(8px);
      }

      to {
        opacity: 1;
        transform: translateY(0);
      }
    }

    /* ─── HERO ─── */
    .hero {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      margin-bottom: 28px;
      align-items: center;
    }

    .hero-tag {
      display: inline-flex;
      align-items: center;
      gap: 7px;
      background: var(--blue-light);
      border: 1px solid var(--blue-mid);
      border-radius: 20px;
      padding: 6px 14px;
      font-size: 12px;
      font-weight: 600;
      color: var(--blue1);
      margin-bottom: 18px;
    }

    .hero-tag .dot {
      width: 6px;
      height: 6px;
      border-radius: 50%;
      background: var(--blue1);
      animation: pulse 2s infinite;
    }

    @keyframes pulse {

      0%,
      100% {
        opacity: 1
      }

      50% {
        opacity: .35
      }
    }

    h1 {
      font-size: 36px;
      font-weight: 700;
      line-height: 1.18;
      color: var(--text-dark);
      margin-bottom: 14px;
      letter-spacing: -.5px;
    }

    h1 em {
      font-style: normal;
      color: var(--blue1);
    }

    .hero-sub {
      font-size: 14.5px;
      color: var(--text-mid);
      line-height: 1.7;
      margin-bottom: 26px;
    }

    .hero-actions {
      display: flex;
      gap: 10px;
      align-items: center;
    }

    .btn-primary {
      padding: 11px 22px;
      background: var(--blue1);
      color: #fff;
      border: none;
      border-radius: var(--radius-xs);
      font-size: 13.5px;
      font-weight: 600;
      cursor: pointer;
      font-family: inherit;
      transition: all .2s;
    }

    .btn-primary:hover {
      background: #3a6fd8;
      transform: translateY(-1px);
    }

    .btn-secondary {
      padding: 11px 22px;
      background: var(--white-glass);
      color: var(--text-mid);
      border: 1px solid var(--blue-mid);
      border-radius: var(--radius-xs);
      font-size: 13.5px;
      font-weight: 500;
      cursor: pointer;
      font-family: inherit;
      transition: all .2s;
    }

    .btn-secondary:hover {
      background: var(--blue-light);
    }

    .hero-stats {
      display: flex;
      gap: 28px;
      margin-top: 26px;
    }

    .stat {
      text-align: center;
    }

    .stat-num {
      font-size: 22px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .stat-lab {
      font-size: 11px;
      color: var(--text-soft);
      margin-top: 2px;
      font-weight: 500;
    }

    /* ─── CARD DEMO / 3D FLIP ─── */
    .snap-demo {
      position: relative;
      height: 310px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .scan-frame {
      position: absolute;
      inset: 20px;
      pointer-events: none;
    }

    .corner {
      position: absolute;
      width: 26px;
      height: 26px;
      border-color: var(--blue1);
      border-style: solid;
      border-width: 3px;
    }

    .corner.tl {
      top: 0;
      left: 0;
      border-right: none;
      border-bottom: none;
      border-radius: 4px 0 0 0;
    }

    .corner.tr {
      top: 0;
      right: 0;
      border-left: none;
      border-bottom: none;
      border-radius: 0 4px 0 0;
    }

    .corner.bl {
      bottom: 0;
      left: 0;
      border-right: none;
      border-top: none;
      border-radius: 0 0 0 4px;
    }

    .corner.br {
      bottom: 0;
      right: 0;
      border-left: none;
      border-top: none;
      border-radius: 0 0 4px 0;
    }

    /* 3D card deck container */
    .card-stack {
      position: relative;
      width: 220px;
      height: 250px;
      perspective: 1000px;
    }

    .stacked-card {
      position: absolute;
      width: 200px;
      height: 240px;
      border-radius: 22px;
      border: 1px solid rgba(255, 255, 255, .75);
    }

    .card-back2 {
      background: rgba(180, 205, 255, .38);
      backdrop-filter: blur(6px);
      transform: rotate(-8deg) translate(-18px, 14px);
    }

    .card-back1 {
      background: rgba(140, 175, 255, .55);
      backdrop-filter: blur(10px);
      transform: rotate(-3deg) translate(-7px, 5px);
    }

    .card-front {
      background: var(--white-glass);
      backdrop-filter: blur(22px);
      -webkit-backdrop-filter: blur(22px);
      transform: rotate(2deg);
      display: flex;
      flex-direction: column;
      padding: 26px 22px;
      cursor: pointer;
      transition: transform .3s;
      box-shadow: 0 8px 32px rgba(74, 127, 232, .18);
      transform-style: preserve-3d;
    }

    .card-front:hover {
      transform: rotate(0) scale(1.02);
    }

    .card-lang {
      font-size: 10px;
      font-weight: 700;
      color: var(--text-soft);
      letter-spacing: 1px;
      margin-bottom: 7px;
    }

    .card-word {
      font-size: 26px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 5px;
      word-break: break-all;
    }

    .card-phonetic {
      font-size: 12.5px;
      color: var(--blue1);
      margin-bottom: 14px;
      font-weight: 500;
    }

    .card-divider {
      height: 1px;
      background: var(--blue-mid);
      margin-bottom: 14px;
    }

    .card-trans {
      font-size: 17px;
      font-weight: 600;
      color: var(--text-mid);
      margin-bottom: 7px;
    }

    .card-example {
      font-size: 11.5px;
      color: var(--text-soft);
      line-height: 1.55;
      font-style: italic;
    }

    /* ─── ADD CARD AREA ─── */
    .add-card-area {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      border: 1.5px dashed var(--blue-mid);
      border-radius: var(--radius);
      padding: 20px 24px;
      display: flex;
      align-items: center;
      gap: 18px;
      cursor: pointer;
      transition: all .2s;
      margin-bottom: 22px;
    }

    .add-card-area:hover {
      border-color: var(--blue1);
      background: var(--blue-light);
    }

    .add-icon {
      width: 44px;
      height: 44px;
      border-radius: 13px;
      background: linear-gradient(135deg, var(--blue-light), var(--blue-mid));
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 22px;
      color: var(--blue1);
      flex-shrink: 0;
      font-weight: 300;
    }

    .add-title {
      font-size: 14px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 3px;
    }

    .add-sub {
      font-size: 12.5px;
      color: var(--text-soft);
    }

    .add-shortcut {
      margin-left: auto;
      display: flex;
      flex-direction: column;
      align-items: flex-end;
      gap: 5px;
    }

    .kbd {
      background: var(--white-glass);
      border: 1px solid var(--blue-mid);
      border-radius: 6px;
      padding: 3px 9px;
      font-size: 11px;
      font-weight: 600;
      color: var(--text-mid);
    }

    /* ─── MAIN GRID ─── */
    .main-grid {
      display: grid;
      grid-template-columns: 270px 1fr;
      gap: 20px;
      margin-bottom: 20px;
    }

    /* ─── SIDEBAR ─── */
    .sidebar-section {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius);
      padding: 18px 20px;
      margin-bottom: 14px;
      box-shadow: var(--shadow-premium);
    }

    .sec-title {
      font-size: 11px;
      font-weight: 700;
      color: var(--text-soft);
      letter-spacing: 1px;
      text-transform: uppercase;
      margin-bottom: 14px;
    }

    .progress-item {
      margin-bottom: 13px;
      padding: 8px 12px;
      border-radius: var(--radius-xs);
      cursor: pointer;
      transition: all 0.2s ease;
      border: 1px solid transparent;
    }

    .progress-item:hover {
      background: var(--blue-light);
      border-color: var(--blue-mid);
    }

    .progress-item.active {
      background: var(--blue-light);
      border-color: var(--blue1);
    }

    .pi-top {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 6px;
    }

    .pi-lang {
      font-size: 13px;
      font-weight: 600;
      color: var(--text-dark);
    }

    .pi-count {
      font-size: 11px;
      color: var(--text-soft);
    }

    .pi-bar {
      height: 6px;
      background: var(--blue-light);
      border-radius: 3px;
      overflow: hidden;
    }

    .pi-fill {
      height: 100%;
      border-radius: 3px;
      background: linear-gradient(90deg, var(--blue1), var(--blue2));
      transition: width 0.4s ease;
    }

    .today-goal {
      display: flex;
      align-items: center;
      gap: 14px;
    }

    .goal-ring {
      position: relative;
      width: 70px;
      height: 70px;
      flex-shrink: 0;
    }

    .goal-ring svg {
      transform: rotate(-90deg);
    }

    .goal-ring-num {
      position: absolute;
      inset: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 15px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .goal-label {
      font-size: 13px;
      font-weight: 600;
      color: var(--text-dark);
      margin-bottom: 4px;
    }

    .goal-sub {
      font-size: 12px;
      color: var(--text-soft);
    }

    .session-btn {
      width: 100%;
      margin-top: 13px;
      padding: 10px;
      background: var(--blue1);
      color: #fff;
      border: none;
      border-radius: var(--radius-xs);
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      font-family: inherit;
      transition: background .2s;
    }

    .session-btn:hover {
      background: #3a6fd8;
    }


    /* ─── FOLDER TREE EXPLORER ─── */
    .folder-tree {
      display: flex;
      flex-direction: column;
      gap: 2px;
    }

    .folder-item {
      display: flex;
      align-items: center;
      gap: 8px;
      padding: 6px 10px;
      border-radius: var(--radius-xs);
      cursor: pointer;
      transition: all 0.2s;
      border: 1px solid transparent;
      color: var(--text-dark);
    }

    .folder-item:hover {
      background: var(--blue-light);
    }

    .folder-item.active {
      background: var(--blue-light);
      border-color: var(--blue1);
    }

    .folder-icon {
      font-size: 16px;
      flex-shrink: 0;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .folder-label {
      font-size: 13px;
      font-weight: 600;
      flex: 1;
    }

    .folder-count {
      font-size: 11px;
      color: var(--text-soft);
      font-weight: 700;
      background: rgba(0, 0, 0, 0.05);
      padding: 2px 6px;
      border-radius: 10px;
      min-width: 20px;
      text-align: center;
    }

    .folder-children {
      margin-left: 17px;
      padding-left: 10px;
      border-left: 1px dashed var(--blue-mid);
      display: flex;
      flex-direction: column;
      gap: 2px;
      margin-top: 2px;
      margin-bottom: 6px;
    }

    /* ─── CARDS AREA ─── */
    .area-top {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 14px;
    }

    .area-title {
      font-size: 15px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .filter-row {
      display: flex;
      gap: 6px;
    }

    .filter-chip {
      padding: 5px 13px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      border: 1px solid var(--blue-mid);
      background: none;
      color: var(--text-mid);
      font-family: inherit;
      transition: all .2s;
    }

    .filter-chip.on {
      background: var(--blue1);
      color: #fff;
      border-color: var(--blue1);
    }

    .search-bar {
      display: flex;
      align-items: center;
      gap: 10px;
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius-xs);
      padding: 9px 15px;
      margin-bottom: 14px;
      box-shadow: var(--shadow-premium);
    }

    .search-bar input {
      flex: 1;
      border: none;
      background: none;
      font-family: inherit;
      font-size: 13.5px;
      color: var(--text-dark);
      outline: none;
    }

    .search-bar input::placeholder {
      color: var(--text-soft);
    }

    .vocab-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
      gap: 12px;
      align-items: start;
    }

    .vocab-card {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius-sm);
      padding: 16px;
      cursor: pointer;
      transition: all .25s cubic-bezier(0.4, 0, 0.2, 1);
      position: relative;
      overflow: hidden;
      box-shadow: var(--shadow-premium);
      min-height: 130px;
      display: flex;
      flex-direction: column;
    }

    .vocab-card::before {
      content: '';
      position: absolute;
      top: -28px;
      right: -28px;
      width: 75px;
      height: 75px;
      border-radius: 50%;
      background: var(--blue-glass);
      transition: all .3s ease;
    }

    .vocab-card:hover {
      transform: translateY(-3px);
      border-color: var(--blue-mid);
      box-shadow: 0 12px 30px rgba(74, 127, 232, 0.15);
    }

    .vocab-card:hover::before {
      width: 115px;
      height: 115px;
      top: -38px;
      right: -38px;
    }

    .vc-word {
      font-size: 17px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 4px;
      word-break: break-all;
      position: relative;
      z-index: 2;
    }

    .vc-trans {
      font-size: 13px;
      color: var(--text-mid);
      margin-bottom: 12px;
      flex: 1;
      position: relative;
      z-index: 2;
    }

    .vc-lang {
      font-size: 10px;
      font-weight: 600;
      color: var(--text-soft);
      letter-spacing: .6px;
      margin-bottom: 8px;
      text-transform: uppercase;
      position: relative;
      z-index: 2;
    }

    .vc-bar {
      height: 3px;
      background: var(--blue-light);
      border-radius: 2px;
      overflow: hidden;
      margin-top: auto;
      position: relative;
      z-index: 2;
    }

    .vc-fill {
      height: 100%;
      border-radius: 2px;
      transition: width 0.3s ease;
    }

    .fill-high {
      background: linear-gradient(90deg, #5DCA8C, #3DA870);
    }

    .fill-mid {
      background: linear-gradient(90deg, #FFD166, #F0A500);
    }

    .fill-low {
      background: linear-gradient(90deg, var(--blue1), var(--blue2));
    }

    /* ─── STUDY TAB ─── */
    .study-modes-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: 20px;
      margin-top: 10px;
    }

    .study-mode-card {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius);
      padding: 24px;
      cursor: pointer;
      transition: all .25s ease;
      box-shadow: var(--shadow-premium);
      display: flex;
      flex-direction: column;
    }

    .study-mode-card:hover {
      transform: translateY(-4px);
      border-color: var(--blue1);
      box-shadow: 0 15px 35px rgba(74, 127, 232, 0.16);
    }

    .smc-icon {
      font-size: 32px;
      margin-bottom: 14px;
    }

    .smc-title {
      font-size: 18px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 6px;
    }

    .smc-desc {
      font-size: 13.5px;
      color: var(--text-mid);
      line-height: 1.5;
      flex-grow: 1;
      margin-bottom: 16px;
    }

    .smc-badge {
      display: inline-block;
      align-self: flex-start;
      padding: 4px 10px;
      border-radius: 20px;
      font-size: 11px;
      font-weight: 600;
      background: var(--blue-light);
      color: var(--blue1);
    }

    /* STUDY SESSION AREA */
    .session-container {
      background: var(--white-glass);
      backdrop-filter: blur(24px);
      border: 1px solid #fff;
      border-radius: var(--radius);
      padding: 30px;
      max-width: 600px;
      margin: 0 auto;
      box-shadow: 0 15px 45px rgba(74, 127, 232, 0.14);
    }

    .session-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 24px;
    }

    .session-title-text {
      font-size: 16px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .session-progress-text {
      font-size: 13px;
      color: var(--text-soft);
      font-weight: 600;
    }

    .session-progress-bar {
      height: 6px;
      background: var(--blue-light);
      border-radius: 3px;
      overflow: hidden;
      margin-bottom: 24px;
    }

    .session-progress-fill {
      height: 100%;
      background: linear-gradient(90deg, var(--blue1), var(--blue2));
      width: 0%;
      transition: width 0.3s ease;
    }

    /* 3D Flip Card in Session */
    .session-card-box {
      perspective: 1000px;
      width: 100%;
      height: 220px;
      margin: 0 auto 24px;
    }

    .s-card {
      width: 100%;
      height: 100%;
      position: relative;
      transform-style: preserve-3d;
      transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
      cursor: pointer;
    }

    .s-card.flipped {
      transform: rotateY(180deg);
    }

    .s-card-front,
    .s-card-back {
      position: absolute;
      width: 100%;
      height: 100%;
      backface-visibility: hidden;
      border-radius: var(--radius-sm);
      border: 1px solid rgba(255, 255, 255, .9);
      padding: 24px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      text-align: center;
      box-shadow: 0 8px 25px rgba(74, 127, 232, 0.06);
    }

    .s-card-front {
      background: var(--white-glass);
      color: var(--text-dark);
    }

    .s-card-back {
      background: linear-gradient(135deg, var(--blue-light) 0%, #FFFFFF 100%);
      color: var(--text-dark);
      transform: rotateY(180deg);
    }

    .sc-word {
      font-size: 32px;
      font-weight: 700;
      margin-bottom: 8px;
    }

    .sc-phonetic {
      font-size: 14px;
      color: var(--blue1);
      font-weight: 500;
      margin-bottom: 12px;
    }

    .sc-hint {
      font-size: 12px;
      color: var(--text-soft);
    }

    .sc-trans {
      font-size: 24px;
      font-weight: 700;
      color: var(--blue1);
      margin-bottom: 10px;
    }

    .sc-example {
      font-size: 13.5px;
      color: var(--text-mid);
      line-height: 1.5;
      font-style: italic;
    }

    /* Inputs / Answer actions */
    .session-actions {
      display: flex;
      gap: 12px;
      justify-content: center;
    }

    .btn-forgot {
      flex: 1;
      padding: 12px;
      background: #FFE4E4;
      color: var(--red-dark);
      border: none;
      border-radius: var(--radius-xs);
      font-size: 14px;
      font-weight: 600;
      cursor: pointer;
      transition: opacity .15s;
    }

    .btn-knew {
      flex: 1;
      padding: 12px;
      background: #D4F4E2;
      color: var(--green-dark);
      border: none;
      border-radius: var(--radius-xs);
      font-size: 14px;
      font-weight: 600;
      cursor: pointer;
      transition: opacity .15s;
    }

    .btn-forgot:hover,
    .btn-knew:hover {
      opacity: 0.85;
    }

    /* Interactive modes layouts */
    .session-input-wrapper {
      margin-bottom: 20px;
    }

    .session-input {
      width: 100%;
      padding: 12px 18px;
      border-radius: var(--radius-xs);
      border: 1px solid var(--blue-mid);
      background: var(--white-glass);
      color: var(--text-dark);
      font-family: inherit;
      font-size: 15px;
      outline: none;
      text-align: center;
      transition: border-color 0.2s;
    }

    .session-input:focus {
      border-color: var(--blue1);
    }

    .quiz-options {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      margin-bottom: 20px;
    }

    .quiz-option-btn {
      padding: 14px;
      background: var(--white-glass);
      border: 1px solid var(--blue-mid);
      border-radius: var(--radius-xs);
      font-family: inherit;
      font-size: 13.5px;
      font-weight: 600;
      color: var(--text-mid);
      cursor: pointer;
      transition: all 0.2s;
      text-align: center;
    }

    .quiz-option-btn:hover {
      background: var(--blue-light);
      border-color: var(--blue2);
      color: var(--blue1);
    }

    .quiz-option-btn.correct {
      background: #D4F4E2 !important;
      border-color: var(--green) !important;
      color: var(--green-dark) !important;
    }

    .quiz-option-btn.wrong {
      background: #FFE4E4 !important;
      border-color: var(--red) !important;
      color: var(--red-dark) !important;
    }

    .audio-play-btn {
      width: 64px;
      height: 64px;
      border-radius: 50%;
      background: var(--blue-light);
      border: 1px solid var(--blue-mid);
      color: var(--blue1);
      font-size: 24px;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      margin: 0 auto 20px;
      transition: all 0.2s;
    }

    .audio-play-btn:hover {
      background: var(--blue1);
      color: #fff;
      transform: scale(1.05);
    }

    /* ─── STATS TAB ─── */
    .stats-summary {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 16px;
      margin-bottom: 24px;
    }

    .stat-box {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius-sm);
      padding: 20px;
      text-align: center;
      box-shadow: var(--shadow-premium);
    }

    .stat-box-num {
      font-size: 28px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 4px;
    }

    .stat-box-label {
      font-size: 11px;
      font-weight: 700;
      color: var(--text-soft);
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .stats-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 20px;
      margin-bottom: 20px;
    }

    .stats-panel {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius);
      padding: 24px;
      box-shadow: var(--shadow-premium);
    }

    /* Activity graph */
    .activity-chart {
      display: flex;
      justify-content: space-between;
      align-items: flex-end;
      height: 160px;
      padding: 10px 0;
      margin-top: 15px;
    }

    .chart-col {
      display: flex;
      flex-direction: column;
      align-items: center;
      width: calc(100% / 7 - 8px);
    }

    .chart-bar {
      width: 100%;
      background: var(--blue-light);
      border-radius: 6px;
      position: relative;
      height: 140px;
      display: flex;
      align-items: flex-end;
    }

    .chart-fill {
      width: 100%;
      border-radius: 6px;
      background: linear-gradient(180deg, var(--blue2), var(--blue1));
      height: 0%;
      transition: height 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    }

    .chart-label {
      font-size: 11px;
      font-weight: 600;
      color: var(--text-soft);
      margin-top: 8px;
    }

    .weak-words-list {
      display: flex;
      flex-direction: column;
      gap: 10px;
      margin-top: 14px;
    }

    .weak-word-item {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 10px 14px;
      border-radius: var(--radius-xs);
      background: rgba(255, 255, 255, 0.5);
      border: 1px solid var(--blue-light);
    }

    .wwi-word {
      font-size: 14px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .wwi-stats {
      font-size: 12px;
      color: var(--text-soft);
    }

    .wwi-stats span {
      color: var(--red);
      font-weight: 600;
    }

    /* ─── GOALS TAB ─── */
    .goals-hero {
      display: grid;
      grid-template-columns: 1.5fr 1fr;
      gap: 20px;
      margin-bottom: 24px;
    }

    .goals-ring-panel {
      display: flex;
      align-items: center;
      gap: 24px;
    }

    .achievements-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
      margin-top: 14px;
    }

    .ach-card {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius-sm);
      padding: 18px;
      display: flex;
      align-items: center;
      gap: 16px;
      box-shadow: var(--shadow-premium);
      opacity: 0.5;
      transition: opacity 0.3s ease;
    }

    .ach-card.unlocked {
      opacity: 1;
      border-color: var(--blue-mid);
    }

    .ach-icon {
      font-size: 32px;
      background: var(--blue-light);
      width: 54px;
      height: 54px;
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .ach-card.unlocked .ach-icon {
      background: linear-gradient(135deg, #FFF6E0, #FFE699);
    }

    .ach-title {
      font-size: 14px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .ach-desc {
      font-size: 12px;
      color: var(--text-soft);
      margin-top: 3px;
    }

    /* ─── SETTINGS TAB ─── */
    .settings-panel {
      max-width: 650px;
      margin: 0 auto;
    }

    .settings-group {
      margin-bottom: 22px;
    }

    .settings-label {
      display: block;
      font-size: 13.5px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 8px;
    }

    .settings-input {
      width: 100%;
      padding: 11px 16px;
      border-radius: var(--radius-xs);
      border: 1px solid var(--blue-mid);
      background: var(--white-glass);
      font-family: inherit;
      font-size: 14px;
      color: var(--text-dark);
      outline: none;
    }

    .settings-input:focus {
      border-color: var(--blue1);
    }

    .settings-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
      margin-bottom: 22px;
    }

    .btn-danger {
      padding: 11px 22px;
      background: #FFE4E4;
      color: var(--red-dark);
      border: 1px solid #FFD1D1;
      border-radius: var(--radius-xs);
      font-size: 13.5px;
      font-weight: 600;
      cursor: pointer;
      font-family: inherit;
      transition: all .2s;
    }

    .btn-danger:hover {
      background: #FFD1D1;
    }

    /* ─── MODAL DIALOG ─── */
    .modal-overlay {
      position: fixed;
      inset: 0;
      background: rgba(26, 43, 94, 0.4);
      backdrop-filter: blur(8px);
      z-index: 1000;
      display: flex;
      align-items: center;
      justify-content: center;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.3s ease;
    }

    .modal-overlay.open {
      opacity: 1;
      pointer-events: auto;
    }

    .modal-content {
      background: var(--white-glass);
      backdrop-filter: blur(24px);
      border: 1px solid #fff;
      border-radius: var(--radius);
      padding: 28px;
      width: 100%;
      max-width: 520px;
      box-shadow: 0 20px 50px rgba(74, 127, 232, 0.25);
      transform: scale(0.92);
      transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
    }

    .modal-overlay.open .modal-content {
      transform: scale(1);
    }

    .modal-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 20px;
    }

    .modal-title {
      font-size: 18px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .modal-close {
      background: none;
      border: none;
      font-size: 20px;
      color: var(--text-soft);
      cursor: pointer;
    }

    /* ─── BOTTOM ROW ─── */
    .bottom-row {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 16px;
      margin-top: 20px;
    }

    .bottom-card {
      background: var(--white-glass);
      backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, .9);
      border-radius: var(--radius);
      padding: 20px;
      box-shadow: var(--shadow-premium);
    }

    .bc-title {
      font-size: 14px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 6px;
    }

    .bc-sub {
      font-size: 12.5px;
      color: var(--text-soft);
      line-height: 1.55;
    }

    .mini-stat {
      display: flex;
      justify-content: space-between;
      margin-top: 14px;
      padding-top: 14px;
      border-top: 1px solid var(--blue-light);
    }

    .ms-item {
      text-align: center;
    }

    .ms-num {
      font-size: 17px;
      font-weight: 700;
      color: var(--text-dark);
    }

    .ms-lab {
      font-size: 10px;
      color: var(--text-soft);
    }

    .badge-row {
      display: flex;
      gap: 7px;
      margin-top: 12px;
      flex-wrap: wrap;
    }

    .badge {
      padding: 4px 10px;
      border-radius: 20px;
      font-size: 11px;
      font-weight: 600;
    }

    .badge-en {
      background: #EEF3FF;
      color: var(--blue1);
    }

    .badge-de {
      background: #E8F5EC;
      color: #1A6B40;
    }

    .badge-jp {
      background: #FFF0F0;
      color: #8B2020;
    }

    .sync-item {
      display: flex;
      align-items: center;
      gap: 10px;
      padding: 8px 0;
      border-bottom: 1px solid var(--blue-light);
    }

    .sync-item:last-child {
      border-bottom: none;
    }

    .sync-dot {
      width: 7px;
      height: 7px;
      border-radius: 50%;
      flex-shrink: 0;
    }

    .sync-green {
      background: #5DCA8C;
    }

    .sync-text {
      font-size: 12px;
      color: var(--text-mid);
      flex: 1;
    }

    .sync-time {
      font-size: 11px;
      color: var(--text-soft);
    }

    /* Details card overlay */
    .card-details-box {
      margin-top: 12px;
      padding: 12px;
      border-radius: var(--radius-xs);
      background: var(--blue-light);
      font-size: 12px;
      color: var(--text-mid);
    }

    .card-details-source {
      font-weight: 700;
      color: var(--blue1);
      text-decoration: underline;
      cursor: pointer;
    }

    /* ─── AUTH OVERLAY ─── */
    .auth-overlay-premium {
      position: fixed;
      top: 0; left: 0; width: 100%; height: 100%;
      background: #1a1f3d;
      z-index: 10000;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: opacity 0.5s ease;
      overflow: hidden;
    }

    /* Animated gradient blobs behind the card */
    .auth-overlay-premium::before,
    .auth-overlay-premium::after {
      content: '';
      position: absolute;
      border-radius: 50%;
      filter: blur(80px);
      opacity: 0.5;
      z-index: 0;
    }
    .auth-overlay-premium::before {
      width: 400px; height: 400px;
      background: #4A7FE8;
      top: -80px; left: -80px;
      animation: authBlob1 8s ease-in-out infinite alternate;
    }
    .auth-overlay-premium::after {
      width: 350px; height: 350px;
      background: #5DCA8C;
      bottom: -60px; right: -60px;
      animation: authBlob2 10s ease-in-out infinite alternate;
    }
    @keyframes authBlob1 {
      0% { transform: translate(0, 0) scale(1); }
      100% { transform: translate(80px, 60px) scale(1.2); }
    }
    @keyframes authBlob2 {
      0% { transform: translate(0, 0) scale(1); }
      100% { transform: translate(-60px, -80px) scale(1.15); }
    }

    .auth-card-premium {
      position: relative;
      z-index: 1;
      background: #ffffff;
      border-radius: 28px;
      padding: 48px 44px;
      width: 100%;
      max-width: 430px;
      box-shadow: 0 30px 80px rgba(0, 0, 0, 0.3);
      text-align: center;
      animation: authCardIn 0.6s cubic-bezier(0.16, 1, 0.3, 1) forwards;
      color: #1a2b5e;
    }

    @keyframes authCardIn {
      0% { opacity: 0; transform: translateY(30px) scale(0.96); }
      100% { opacity: 1; transform: translateY(0) scale(1); }
    }

    /* Auth card headings */
    .auth-card-premium h2 {
      color: #1a2b5e;
      font-size: 26px;
      font-weight: 800;
      margin-bottom: 8px;
    }
    .auth-card-premium .auth-subtitle {
      color: #5a6a9a;
      font-size: 15px;
      line-height: 1.5;
      margin-bottom: 28px;
    }

    /* Auth logo area */
    .auth-logo-area {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      margin-bottom: 32px;
    }
    .auth-logo-icon {
      width: 48px; height: 48px;
      background: linear-gradient(135deg, #4A7FE8, #6B9BFF);
      border-radius: 14px;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 8px 20px rgba(74, 127, 232, 0.35);
    }
    .auth-logo-icon svg {
      width: 26px; height: 26px;
    }
    .auth-logo-text {
      font-size: 30px;
      font-weight: 800;
      color: #1a2b5e;
      letter-spacing: -0.5px;
    }
    .auth-logo-text span {
      color: #4A7FE8;
    }

    /* Inputs */
    .auth-input-premium {
      width: 100%;
      padding: 15px 18px;
      border: 2px solid #e2e8f0;
      border-radius: 14px;
      margin-bottom: 14px;
      font-family: 'Manrope', sans-serif;
      font-size: 15px;
      background: #f8fafc;
      color: #1e293b;
      transition: all 0.25s ease;
    }
    .auth-input-premium::placeholder {
      color: #94a3b8;
    }
    .auth-input-premium:focus {
      outline: none;
      border-color: #4A7FE8;
      background: #fff;
      box-shadow: 0 0 0 4px rgba(74, 127, 232, 0.12);
    }

    /* Primary button */
    .auth-btn-primary {
      width: 100%;
      padding: 16px;
      border: none;
      border-radius: 14px;
      font-family: 'Manrope', sans-serif;
      font-size: 16px;
      font-weight: 700;
      color: #ffffff;
      background: linear-gradient(135deg, #4A7FE8, #6B9BFF);
      cursor: pointer;
      transition: all 0.3s ease;
      box-shadow: 0 6px 20px rgba(74, 127, 232, 0.3);
    }
    .auth-btn-primary:hover {
      transform: translateY(-2px);
      box-shadow: 0 10px 30px rgba(74, 127, 232, 0.4);
    }

    /* Google button */
    .auth-btn-google {
      width: 100%;
      padding: 15px;
      border: 2px solid #e2e8f0;
      border-radius: 14px;
      font-family: 'Manrope', sans-serif;
      font-size: 15px;
      font-weight: 600;
      color: #334155;
      background: #ffffff;
      cursor: pointer;
      transition: all 0.25s ease;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
    }
    .auth-btn-google:hover {
      background: #f1f5f9;
      border-color: #cbd5e1;
      transform: translateY(-1px);
      box-shadow: 0 4px 12px rgba(0,0,0,0.06);
    }

    /* Divider */
    .auth-divider {
      display: flex;
      align-items: center;
      margin: 22px 0;
      gap: 14px;
    }
    .auth-divider::before, .auth-divider::after {
      content: '';
      flex: 1;
      height: 1px;
      background: #e2e8f0;
    }
    .auth-divider span {
      color: #94a3b8;
      font-size: 13px;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 1px;
    }

    /* Error box */
    .auth-error-box {
      color: #dc2626;
      font-size: 13px;
      margin-bottom: 14px;
      display: none;
      background: #fef2f2;
      border: 1px solid #fecaca;
      padding: 10px 14px;
      border-radius: 10px;
      text-align: left;
    }

    /* Footer link */
    .auth-footer {
      margin-top: 28px;
      font-size: 15px;
      color: #64748b;
    }
    .auth-footer a {
      color: #4A7FE8;
      font-weight: 700;
      text-decoration: none;
    }
    .auth-footer a:hover {
      text-decoration: underline;
    }