:root {
    --bg: #0D0D0F;
    --surface: #141417;
    --surface2: #1C1C20;
    --border: rgba(255,255,255,0.07);
    --border-hover: rgba(255,255,255,0.15);
    --text: #F0EDE8;
    --muted: #6B6877;
    --muted2: #9B98A8;
    --accent: #C8F542;
    --accent-dim: rgba(200,245,66,0.12);
    --accent-glow: rgba(200,245,66,0.25);
    --warm: #FF7B54;
    --warm-dim: rgba(255,123,84,0.12);
    --blue: #7EB8F7;
    --blue-dim: rgba(126,184,247,0.1);
    --radius: 16px;
    --ease: cubic-bezier(0.22, 1, 0.36, 1);
  }

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

  body {
    font-family: 'Syne', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
  }

  /* Grain overlay */
  body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.035'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 1000;
    opacity: 0.4;
  }

  /* ── HEADER ── */
  header {
    padding: 1.1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--border);
    background: rgba(13,13,15,0.85);
    backdrop-filter: blur(20px);
    position: sticky;
    top: 0;
    z-index: 100;
  }

  .logo {
    font-family: 'Playfair Display', serif;
    font-size: 1.35rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }

  .logo-dot {
    width: 8px;
    height: 8px;
    background: var(--accent);
    border-radius: 50%;
    box-shadow: 0 0 10px var(--accent-glow);
    animation: pulse-dot 2.5s ease-in-out infinite;
  }

  @keyframes pulse-dot {
    0%, 100% { transform: scale(1); opacity: 1; }
    50% { transform: scale(1.4); opacity: 0.7; }
  }

  .header-right {
    display: flex;
    align-items: center;
    gap: 0.75rem;
  }

  .lang-pill {
    background: var(--surface2);
    border: 1px solid var(--border);
    color: var(--muted2);
    padding: 4px 12px;
    border-radius: 100px;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    font-family: 'JetBrains Mono', monospace;
  }

  #reset-btn {
    background: transparent;
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 6px 14px;
    font-family: 'Syne', sans-serif;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--muted);
    cursor: pointer;
    transition: all 0.2s var(--ease);
    letter-spacing: 0.03em;
  }
  #reset-btn:hover {
    background: var(--surface2);
    color: var(--text);
    border-color: var(--border-hover);
  }

  /* ── SCREENS ── */
  .screen { display: none; flex: 1; }
  .screen.active { display: flex; }

  /* ── WELCOME SCREEN ── */
  #welcome-screen {
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 4rem 1.5rem;
    position: relative;
    animation: fadeIn 0.6s var(--ease) both;
  }

  /* Radial glow background */
  #welcome-screen::after {
    content: '';
    position: absolute;
    top: 20%;
    left: 50%;
    transform: translateX(-50%);
    width: 600px;
    height: 400px;
    background: radial-gradient(ellipse, rgba(200,245,66,0.05) 0%, transparent 70%);
    pointer-events: none;
  }

  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(24px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .welcome-eyebrow {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72rem;
    font-weight: 400;
    color: var(--accent);
    letter-spacing: 0.15em;
    text-transform: uppercase;
    margin-bottom: 1.25rem;
    position: relative;
    z-index: 1;
  }

  .welcome-title {
    font-family: 'Playfair Display', serif;
    font-size: clamp(2.4rem, 6vw, 4rem);
    font-weight: 700;
    line-height: 1.05;
    letter-spacing: -0.03em;
    text-align: center;
    margin-bottom: 0.75rem;
    position: relative;
    z-index: 1;
  }

  .welcome-title em {
    font-style: italic;
    font-weight: 400;
    color: var(--muted2);
  }

  .welcome-sub {
    color: var(--muted);
    font-size: 0.9rem;
    text-align: center;
    margin-bottom: 3rem;
    max-width: 340px;
    line-height: 1.6;
    font-weight: 400;
    position: relative;
    z-index: 1;
  }

  /* Form card */
  .form-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 2rem;
    width: 100%;
    max-width: 440px;
    position: relative;
    z-index: 1;
    box-shadow: 0 0 60px rgba(0,0,0,0.5);
  }

  .form-group { margin-bottom: 1.25rem; }
  .form-group:last-of-type { margin-bottom: 0; }

  .form-group label {
    display: block;
    font-size: 0.68rem;
    font-weight: 700;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.12em;
    margin-bottom: 0.5rem;
  }

  .select-wrap {
    position: relative;
  }

  .form-group select {
    width: 100%;
    padding: 0.8rem 2.5rem 0.8rem 1rem;
    border: 1px solid var(--border);
    border-radius: 12px;
    font-family: 'Syne', sans-serif;
    font-size: 0.95rem;
    font-weight: 500;
    background: var(--surface2);
    color: var(--text);
    appearance: none;
    cursor: pointer;
    transition: all 0.2s var(--ease);
    outline: none;
  }
  .form-group select:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-dim);
  }
  .form-group select:hover {
    border-color: var(--border-hover);
  }

  .select-wrap::after {
    content: '';
    position: absolute;
    right: 14px;
    top: 50%;
    transform: translateY(-50%);
    width: 10px;
    height: 6px;
    background: var(--muted);
    clip-path: polygon(0 0, 100% 0, 50% 100%);
    pointer-events: none;
  }

  .divider {
    border: none;
    border-top: 1px solid var(--border);
    margin: 1.25rem 0;
    position: relative;
  }
  .divider::after {
    content: '→';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--surface);
    color: var(--muted);
    padding: 0 0.75rem;
    font-size: 0.75rem;
  }

  .start-btn {
    width: 100%;
    padding: 1rem;
    background: var(--accent);
    color: #0D0D0F;
    border: none;
    border-radius: 12px;
    font-family: 'Syne', sans-serif;
    font-size: 0.95rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s var(--ease);
    margin-top: 1.5rem;
    letter-spacing: 0.02em;
    position: relative;
    overflow: hidden;
  }
  .start-btn::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(105deg, transparent 40%, rgba(255,255,255,0.2) 50%, transparent 60%);
    transform: translateX(-100%);
    transition: transform 0.5s ease;
  }
  .start-btn:hover::after { transform: translateX(100%); }
  .start-btn:hover {
    background: #d8ff4a;
    box-shadow: 0 0 30px var(--accent-glow);
    transform: translateY(-1px);
  }
  .start-btn:active { transform: translateY(0); }

  .practice-link {
    margin-top: 1.1rem;
    font-size: 0.8rem;
    color: var(--muted);
    text-align: center;
    cursor: pointer;
    transition: color 0.2s;
    font-weight: 500;
  }
  .practice-link:hover { color: var(--blue); }
  .practice-link span {
    text-decoration: underline;
    text-underline-offset: 3px;
  }

  /* ── STUDY SCREEN ── */
  #study-screen {
    flex-direction: column;
    padding: 2rem 1.5rem 3rem;
    max-width: 900px;
    margin: 0 auto;
    width: 100%;
    animation: fadeIn 0.4s var(--ease) both;
  }

  .study-header {
    margin-bottom: 2rem;
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
  }

  .study-title {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.5rem, 3vw, 2.2rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    line-height: 1;
  }

  .study-title em {
    font-style: italic;
    font-weight: 400;
    color: var(--accent);
  }

  .progress-wrap {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.4rem;
  }

  .progress-text {
    font-size: 0.72rem;
    color: var(--muted);
    font-family: 'JetBrains Mono', monospace;
    font-weight: 400;
  }

  .progress-bar-bg {
    width: 160px;
    height: 3px;
    background: var(--surface2);
    border-radius: 2px;
    overflow: hidden;
  }

  .progress-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), #a8e820);
    border-radius: 2px;
    transition: width 0.5s var(--ease);
    box-shadow: 0 0 8px var(--accent-glow);
  }

  /* Stats row */
  .stats-row {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.75rem;
    margin-bottom: 1.75rem;
  }

  .stat-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1.1rem 1rem;
    text-align: center;
    transition: border-color 0.2s;
    position: relative;
    overflow: hidden;
  }

  .stat-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, transparent 60%, rgba(255,255,255,0.02));
    pointer-events: none;
  }

  .stat-card:hover { border-color: var(--border-hover); }

  .stat-value {
    font-family: 'Playfair Display', serif;
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.04em;
    color: var(--text);
    line-height: 1;
    margin-bottom: 0.3rem;
  }

  .stat-label {
    font-size: 0.65rem;
    color: var(--muted);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
  }

  /* Category tabs */
  .cat-tabs {
    display: flex;
    gap: 0.4rem;
    margin-bottom: 1.25rem;
    flex-wrap: wrap;
  }

  .cat-tab {
    padding: 6px 14px;
    border-radius: 100px;
    font-size: 0.75rem;
    font-weight: 600;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--muted);
    cursor: pointer;
    transition: all 0.15s var(--ease);
    letter-spacing: 0.02em;
    font-family: 'Syne', sans-serif;
  }
  .cat-tab.active {
    background: var(--accent);
    border-color: var(--accent);
    color: #0D0D0F;
  }
  .cat-tab:hover:not(.active) {
    border-color: var(--border-hover);
    color: var(--text);
    background: var(--surface2);
  }

  /* Search */
  .search-wrap {
    position: relative;
    margin-bottom: 1.5rem;
  }

  .search-icon {
    position: absolute;
    left: 14px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--muted);
    pointer-events: none;
  }

  .search-wrap input {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.75rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    font-family: 'Syne', sans-serif;
    font-size: 0.9rem;
    color: var(--text);
    transition: all 0.2s var(--ease);
    outline: none;
  }
  .search-wrap input::placeholder { color: var(--muted); }
  .search-wrap input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-dim);
  }

  /* Phrase cards */
  .phrases-list {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
  }

  .phrase-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    cursor: pointer;
    transition: all 0.2s var(--ease);
    position: relative;
    overflow: hidden;
  }

  .phrase-card::after {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: radial-gradient(ellipse at var(--mx, 50%) var(--my, 50%), rgba(200,245,66,0.04) 0%, transparent 60%);
    opacity: 0;
    transition: opacity 0.3s;
    pointer-events: none;
  }

  .phrase-card:hover::after { opacity: 1; }

  .phrase-card:hover {
    border-color: var(--border-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 32px rgba(0,0,0,0.35);
  }

  .phrase-card.practiced {
    opacity: 0.5;
  }

  .phrase-card.practiced .phrase-target {
    text-decoration: line-through;
    text-decoration-color: var(--muted);
  }

  .card-inner {
    display: flex;
    align-items: flex-start;
    gap: 1.25rem;
  }

  .card-number {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.68rem;
    color: var(--muted);
    font-weight: 300;
    min-width: 36px;
    padding-top: 4px;
    flex-shrink: 0;
  }

  .card-body { flex: 1; min-width: 0; }

  .card-cat {
    display: inline-block;
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--muted);
    margin-bottom: 0.5rem;
  }

  .phrase-target {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.2rem, 2.5vw, 1.6rem);
    font-weight: 700;
    letter-spacing: -0.025em;
    line-height: 1.2;
    margin-bottom: 0.5rem;
    color: var(--text);
  }

  .phrase-phonetic {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    color: var(--blue);
    font-weight: 300;
    margin-bottom: 0.6rem;
  }

  .phrase-divider {
    border: none;
    border-top: 1px solid var(--border);
    margin: 0.6rem 0;
  }

  .phrase-translation {
    font-size: 0.88rem;
    color: var(--muted2);
    font-weight: 400;
    line-height: 1.4;
  }

  .card-actions {
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex-shrink: 0;
    margin-top: 2px;
  }

  .btn-play {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--border);
    background: var(--surface2);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s var(--ease);
    color: var(--muted2);
    flex-shrink: 0;
  }
  .btn-play:hover {
    border-color: var(--accent);
    color: var(--accent);
    box-shadow: 0 0 12px var(--accent-dim);
  }
  .btn-play.playing {
    background: var(--accent);
    border-color: var(--accent);
    color: #0D0D0F;
    box-shadow: 0 0 16px var(--accent-glow);
  }
  .btn-play svg { width: 16px; height: 16px; }

  .btn-fav {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--border);
    background: var(--surface2);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s var(--ease);
    color: var(--muted);
    flex-shrink: 0;
    font-size: 1rem;
  }
  .btn-fav.active {
    color: var(--warm);
    border-color: rgba(255,123,84,0.3);
    background: var(--warm-dim);
  }
  .btn-fav:hover:not(.active) {
    border-color: var(--border-hover);
    color: var(--text);
  }

  /* Practiced checkmark */
  .btn-check {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--border);
    background: var(--surface2);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s var(--ease);
    color: var(--muted);
    flex-shrink: 0;
    font-size: 0.85rem;
  }
  .btn-check.done {
    color: var(--accent);
    border-color: var(--accent-glow);
    background: var(--accent-dim);
  }
  .btn-check:hover:not(.done) {
    border-color: var(--border-hover);
    color: var(--text);
  }

  /* Bottom Nav */
  .nav-bottom {
    display: flex;
    justify-content: center;
    gap: 0.6rem;
    margin-top: 2rem;
    padding-top: 1.75rem;
    border-top: 1px solid var(--border);
    flex-wrap: wrap;
  }

  .nav-btn {
    padding: 0.6rem 1.2rem;
    border-radius: 10px;
    border: 1px solid var(--border);
    background: var(--surface);
    font-family: 'Syne', sans-serif;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--muted2);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: all 0.2s var(--ease);
    letter-spacing: 0.02em;
  }
  .nav-btn:hover {
    border-color: var(--border-hover);
    color: var(--text);
    background: var(--surface2);
  }
  .nav-btn.primary {
    background: var(--surface2);
    border-color: var(--border-hover);
    color: var(--text);
  }
  .nav-btn.primary:hover {
    border-color: var(--accent);
    color: var(--accent);
    box-shadow: 0 0 16px var(--accent-dim);
  }

  /* Empty state */
  .empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--muted);
  }
  .empty-state .icon { font-size: 2.5rem; margin-bottom: 0.75rem; }
  .empty-state p { font-size: 0.88rem; }

  /* Toast */
  .toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(80px);
    background: var(--surface2);
    border: 1px solid var(--border-hover);
    color: var(--text);
    padding: 0.65rem 1.25rem;
    border-radius: 100px;
    font-size: 0.8rem;
    font-weight: 600;
    white-space: nowrap;
    transition: transform 0.35s var(--ease), opacity 0.35s;
    opacity: 0;
    z-index: 999;
    box-shadow: 0 8px 32px rgba(0,0,0,0.5);
    letter-spacing: 0.02em;
  }
  .toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
  }

  /* Scrollbar */
  ::-webkit-scrollbar { width: 6px; }
  ::-webkit-scrollbar-track { background: var(--bg); }
  ::-webkit-scrollbar-thumb { background: var(--surface2); border-radius: 3px; }
  ::-webkit-scrollbar-thumb:hover { background: var(--border-hover); }

  /* Responsive */
  @media (max-width: 600px) {
    header { padding: 1rem 1rem; }
    #study-screen { padding: 1.5rem 1rem 3rem; }
    .stats-row { gap: 0.5rem; }
    .stat-card { padding: 0.8rem; }
    .stat-value { font-size: 1.5rem; }
    .phrase-card { padding: 1.15rem; }
    .card-number { display: none; }
    .start-btn { font-size: 0.9rem; }
  }