:root{--color-bg: #f5f3ff;--color-surface: #ffffff;--color-primary: #6c5ce7;--color-primary-dark: #5646c9;--color-secondary: #17c3b2;--color-success: #58cc02;--color-success-dark: #46a302;--color-danger: #ff5c5c;--color-danger-dark: #e14545;--color-streak: #ff9f1c;--color-text: #2d2a45;--color-text-muted: #8987a6;--color-border: #e7e4fa;--radius-sm: 10px;--radius-md: 18px;--radius-lg: 26px;--shadow-card: 0 4px 16px rgba(108, 92, 231, .12);--shadow-pop: 0 6px 0 rgba(0, 0, 0, .08);--font-display: "Baloo 2", "Nunito", sans-serif;--font-body: "Nunito", sans-serif;--nav-height: 68px}*{box-sizing:border-box}body{background:var(--color-bg);color:var(--color-text);font-family:var(--font-body)}.app-root{max-width:520px;margin:0 auto;min-height:100vh;display:flex;flex-direction:column;background:var(--color-bg)}button{font-family:var(--font-display);cursor:pointer}.login-screen{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:24px;text-align:center;gap:8px}.login-mascot{font-size:4rem;margin-bottom:4px;animation:bounce-in .6s ease}.login-title{font-family:var(--font-display);font-size:2rem;font-weight:800;color:var(--color-primary);margin:0}.login-subtitle{color:var(--color-text-muted);margin:0 0 16px}.pin-input{font-family:var(--font-display);font-size:1.75rem;letter-spacing:.5rem;text-align:center;width:220px;padding:14px 10px 14px 20px;border:3px solid var(--color-border);border-radius:var(--radius-md);outline:none;transition:border-color .15s ease}.pin-input:focus{border-color:var(--color-primary)}.login-error{color:var(--color-danger);font-weight:700;animation:shake .4s ease}.btn{font-family:var(--font-display);font-weight:700;font-size:1rem;border:none;border-radius:var(--radius-md);padding:14px 28px;color:#fff;background:var(--color-primary);box-shadow:0 4px 0 var(--color-primary-dark);transition:transform .08s ease,box-shadow .08s ease}.btn:active:not(:disabled){transform:translateY(3px);box-shadow:0 1px 0 var(--color-primary-dark)}.btn:disabled{opacity:.4;cursor:not-allowed;box-shadow:none}.btn-success{background:var(--color-success);box-shadow:0 4px 0 var(--color-success-dark)}.btn-outline{background:var(--color-surface);color:var(--color-primary);border:2px solid var(--color-border);box-shadow:none}.app-header{display:flex;align-items:center;justify-content:space-between;padding:16px 20px 8px}.app-logo{font-family:var(--font-display);font-weight:800;font-size:1.4rem;color:var(--color-primary);margin:0}.streak-badge{display:flex;align-items:center;gap:6px;background:var(--color-surface);border-radius:999px;padding:6px 14px;box-shadow:var(--shadow-card);font-weight:800;font-family:var(--font-display)}.streak-flame{font-size:1.2rem;filter:grayscale(0)}.streak-flame.cold{filter:grayscale(1);opacity:.5}.logout-btn{background:var(--color-surface);border:none;border-radius:999px;width:40px;height:40px;font-size:1.1rem;box-shadow:var(--shadow-card);display:flex;align-items:center;justify-content:center;transition:transform .1s ease}.logout-btn:active{transform:scale(.9)}.lang-row{display:flex;gap:10px;padding:0 20px 12px;overflow-x:auto}.lang-chip{flex:0 0 auto;display:flex;align-items:center;gap:6px;background:var(--color-surface);border:2px solid var(--color-border);border-radius:999px;padding:8px 16px;font-family:var(--font-display);font-weight:700;font-size:.9rem;color:var(--color-text-muted);transition:transform .1s ease}.lang-chip.active{border-color:var(--color-primary);color:var(--color-primary);background:#ede9ff;transform:scale(1.05)}.lang-chip.locked{opacity:.55}.lang-flag{font-size:1.1rem}.toast{position:fixed;bottom:calc(var(--nav-height) + 16px);left:50%;transform:translate(-50%);background:var(--color-text);color:#fff;padding:10px 20px;border-radius:999px;font-weight:700;font-size:.9rem;box-shadow:0 6px 20px #0003;animation:toast-in .25s ease;z-index:50;white-space:nowrap}.app-content{flex:1;padding:8px 20px calc(var(--nav-height) + 24px)}.card{background:var(--color-surface);border-radius:var(--radius-lg);box-shadow:var(--shadow-card);padding:20px;margin-bottom:16px}.section-title{font-family:var(--font-display);font-weight:700;font-size:1.1rem;margin:0 0 10px}.bottom-nav{position:fixed;bottom:0;left:50%;transform:translate(-50%);width:100%;max-width:520px;height:var(--nav-height);background:var(--color-surface);border-top:1px solid var(--color-border);display:flex;padding-bottom:env(safe-area-inset-bottom)}.nav-btn{flex:1;background:none;border:none;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:2px;color:var(--color-text-muted);font-size:.7rem;font-weight:700;transition:color .15s ease,transform .15s ease}.nav-btn .nav-icon{font-size:1.4rem}.nav-btn.active{color:var(--color-primary);transform:translateY(-2px)}.session-progress{display:flex;align-items:center;gap:10px;margin-bottom:18px}.progress-track{flex:1;height:12px;background:var(--color-border);border-radius:999px;overflow:hidden}.progress-fill{height:100%;background:var(--color-secondary);border-radius:999px;transition:width .4s ease}.progress-fill.success{background:var(--color-success)}.progress-fill.danger{background:var(--color-danger)}.flip-card{perspective:1200px;height:220px;margin-bottom:20px}.flip-card-inner{position:relative;width:100%;height:100%;transition:transform .5s cubic-bezier(.4,.2,.2,1);transform-style:preserve-3d}.flip-card-inner.flipped{transform:rotateY(180deg)}.flip-face{position:absolute;top:0;right:0;bottom:0;left:0;backface-visibility:hidden;border-radius:var(--radius-lg);box-shadow:var(--shadow-card);display:flex;align-items:center;justify-content:center;flex-direction:column;padding:20px;text-align:center;gap:8px}.flip-face-front{background:linear-gradient(160deg,var(--color-primary),#8a7cf0);color:#fff}.flip-face-back{background:var(--color-surface);transform:rotateY(180deg);border:2px solid var(--color-border)}.flip-face-word{font-family:var(--font-display);font-size:2.2rem;font-weight:700}.flip-face-hint{font-size:.85rem;opacity:.8}.rating-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.rating-btn{border:none;border-radius:var(--radius-sm);padding:12px 4px;font-weight:800;font-size:.85rem;color:#fff;transition:transform .08s ease}.rating-btn:active{transform:scale(.94)}.rating-forgot{background:var(--color-danger)}.rating-hard{background:var(--color-streak)}.rating-good{background:var(--color-secondary)}.rating-easy{background:var(--color-success)}.empty-state{text-align:center;padding:40px 20px}.empty-state-emoji{font-size:3rem;margin-bottom:8px;display:block}.quiz-question-card{margin-bottom:16px}.quiz-prompt{font-family:var(--font-display);font-weight:700;margin:0 0 12px}.choice-btn{display:block;width:100%;text-align:left;background:var(--color-bg);border:2px solid var(--color-border);border-radius:var(--radius-sm);padding:12px 16px;margin-bottom:8px;font-family:var(--font-body);font-weight:600;color:var(--color-text);transition:border-color .12s ease,background .12s ease}.choice-btn.selected{border-color:var(--color-primary);background:#ede9ff}.choice-btn.correct{border-color:var(--color-success);background:#eafce0}.choice-btn.incorrect{border-color:var(--color-danger);background:#ffeaea}.choice-btn:disabled{cursor:default}.quiz-result{text-align:center;padding:20px}.quiz-result-emoji{font-size:3.5rem;animation:bounce-in .5s ease}.quiz-result-score{font-family:var(--font-display);font-size:2rem;font-weight:800;color:var(--color-primary);margin:8px 0}.module-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin-bottom:16px}.module-chip{background:var(--color-surface);border:2px solid var(--color-border);border-radius:var(--radius-sm);padding:12px 10px;font-weight:700;font-size:.85rem;text-align:center;transition:transform .1s ease}.module-chip.active{border-color:var(--color-primary);background:#ede9ff;color:var(--color-primary)}.vocab-list{display:flex;flex-direction:column;gap:8px}.vocab-row{display:flex;justify-content:space-between;align-items:baseline;padding:10px 14px;background:var(--color-bg);border-radius:var(--radius-sm)}.vocab-front{font-family:var(--font-display);font-weight:700;font-size:1.1rem}.vocab-back{color:var(--color-text-muted);font-size:.9rem;text-align:right}.grammar-point{margin-bottom:14px}.grammar-title{font-family:var(--font-display);font-weight:700;color:var(--color-primary)}.grammar-examples{margin:6px 0 0;padding-left:20px;color:var(--color-text-muted);font-size:.9rem}.stat-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin-bottom:16px}.stat-card{background:var(--color-surface);border-radius:var(--radius-md);box-shadow:var(--shadow-card);padding:16px;text-align:center}.stat-value{font-family:var(--font-display);font-size:1.8rem;font-weight:800;color:var(--color-primary)}.stat-label{font-size:.8rem;color:var(--color-text-muted);font-weight:700;text-transform:uppercase;letter-spacing:.03em}.heatmap-grid{display:grid;grid-template-columns:repeat(15,1fr);gap:4px}.heatmap-cell{aspect-ratio:1;border-radius:4px;background:var(--color-border)}.heatmap-cell.studied{background:var(--color-success)}.heatmap-cell.frozen{background:var(--color-streak)}@keyframes bounce-in{0%{transform:scale(.5);opacity:0}60%{transform:scale(1.1);opacity:1}to{transform:scale(1)}}@keyframes shake{0%,to{transform:translate(0)}25%{transform:translate(-6px)}75%{transform:translate(6px)}}@keyframes toast-in{0%{transform:translate(-50%) translateY(10px);opacity:0}to{transform:translate(-50%) translateY(0);opacity:1}}@media(max-width:380px){.flip-face-word{font-size:1.7rem}.stat-value{font-size:1.4rem}}