.flash-card{cursor:pointer;height:280px;margin:0 auto;max-width:400px;perspective:1000px;-webkit-user-select:none;user-select:none;width:100%}.flash-card-inner{height:100%;position:relative;text-align:center;transform-style:preserve-3d;transition:transform .6s;width:100%}.flash-card.flipped .flash-card-inner{transform:rotateY(180deg)}.flash-card-back,.flash-card-front{align-items:center;-webkit-backface-visibility:hidden;backface-visibility:hidden;border:2px solid var(--color-border);border-radius:12px;box-shadow:0 4px 12px #0000001a;display:flex;flex-direction:column;height:100%;justify-content:center;padding:var(--spacing-lg);position:absolute;width:100%}.flash-card-front{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff}.flash-card-back{background:linear-gradient(135deg,#f093fb,#f5576c);color:#fff;transform:rotateY(180deg)}.flash-card-content{align-items:center;display:flex;flex-direction:column;gap:var(--spacing-md);width:100%}.flash-card-text{font-size:1.5rem;font-weight:600;line-height:1.3;text-align:center;word-break:break-word}.flash-card-context{font-size:.9rem;font-style:italic;opacity:.9;text-align:center}.flash-card-audio,.flash-card-context{margin-top:var(--spacing-sm)}.audio-button{align-items:center;background:#fff3;border:1px solid #ffffff4d;border-radius:50%;color:#fff;cursor:pointer;display:flex;font-size:1.2rem;height:48px;justify-content:center;transition:all .2s ease;width:48px}.audio-button:hover{background:#ffffff4d;transform:scale(1.05)}.audio-button:active{transform:scale(.95)}.flash-card-instructions{bottom:var(--spacing-sm);font-size:.8rem;left:50%;opacity:.8;position:absolute;text-align:center;transform:translateX(-50%)}.flash-card.disabled{opacity:.6;pointer-events:none}@media (max-width:768px){.flash-card{height:240px;max-width:320px}.flash-card-text{font-size:1.3rem}.flash-card-back,.flash-card-front{padding:var(--spacing-md)}}:root{--color-primary:#2563eb;--color-primary-hover:#1d4ed8;--color-primary-dark:#1d4ed8;--color-primary-light:#dbeafe;--color-secondary:#64748b;--color-secondary-light:#f1f5f9;--color-success:#059669;--color-error:#dc2626;--color-warning:#d97706;--color-background:#fff;--color-surface:#f8fafc;--color-surface-elevated:#fff;--color-surface-hover:#f1f5f9;--color-text-primary:#1e293b;--color-text-secondary:#64748b;--color-text-muted:#94a3b8;--color-border:#e2e8f0;--color-border-light:#f1f5f9;--spacing-xs:0.25rem;--spacing-sm:0.5rem;--spacing-md:1rem;--spacing-lg:1.5rem;--spacing-xl:2rem;--spacing-2xl:3rem;--font-family-base:-apple-system,BlinkMacSystemFont,"Segoe UI","Roboto","Oxygen","Ubuntu","Cantarell","Fira Sans","Droid Sans","Helvetica Neue",sans-serif;--font-family-mono:source-code-pro,Menlo,Monaco,Consolas,"Courier New",monospace;--font-size-xs:0.75rem;--font-size-sm:0.875rem;--font-size-base:1rem;--font-size-lg:1.125rem;--font-size-xl:1.25rem;--font-size-2xl:1.5rem;--font-weight-normal:400;--font-weight-medium:500;--font-weight-semibold:600;--font-weight-bold:700;--line-height-tight:1.25;--line-height-normal:1.5;--line-height-relaxed:1.75;--border-radius-sm:0.25rem;--border-radius-md:0.5rem;--border-radius-lg:0.75rem;--border-radius-xl:1rem;--shadow-sm:0 1px 2px 0 #0000000d;--shadow-md:0 4px 6px -1px #0000001a,0 2px 4px -2px #0000001a;--shadow-lg:0 10px 15px -3px #0000001a,0 4px 6px -4px #0000001a;--transition-fast:150ms ease-in-out;--transition-normal:250ms ease-in-out;--transition-slow:350ms ease-in-out;--z-dropdown:1000;--z-sticky:1020;--z-fixed:1030;--z-modal:1040;--z-tooltip:1050}*{box-sizing:border-box}body{-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background-color:var(--color-background);color:var(--color-text-primary);font-family:var(--font-family-base);font-size:var(--font-size-base);line-height:var(--line-height-normal);margin:0}#root{display:flex;flex-direction:column;min-height:100vh}h1,h2,h3,h4,h5,h6{font-weight:var(--font-weight-semibold);line-height:var(--line-height-tight);margin:0 0 var(--spacing-md) 0}h1{font-size:var(--font-size-2xl)}h2{font-size:var(--font-size-xl)}h3{font-size:var(--font-size-lg)}p{margin:0 0 var(--spacing-md) 0}.sr-only{clip:rect(0,0,0,0);border:0;height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;white-space:nowrap;width:1px}.container{margin:0 auto;max-width:1200px;padding:0 var(--spacing-md)}.button{align-items:center;border:1px solid #0000;border-radius:var(--border-radius-md);cursor:pointer;display:inline-flex;font-size:var(--font-size-sm);font-weight:var(--font-weight-medium);justify-content:center;padding:var(--spacing-sm) var(--spacing-md);text-decoration:none;transition:all var(--transition-fast)}.button:disabled{cursor:not-allowed;opacity:.5}.button-primary{background-color:var(--color-primary);color:#fff}.button-primary:hover:not(:disabled){background-color:var(--color-primary-hover)}.button-secondary{background-color:var(--color-secondary-light);border-color:var(--color-border);color:var(--color-text-primary)}.button-secondary:hover:not(:disabled){background-color:var(--color-border)}.input{border:1px solid var(--color-border);border-radius:var(--border-radius-md);font-size:var(--font-size-base);padding:var(--spacing-sm) var(--spacing-md);transition:border-color var(--transition-fast);width:100%}.input:focus{border-color:var(--color-primary);box-shadow:0 0 0 3px var(--color-primary-light);outline:none}.loading-spinner{animation:spin 1s ease-in-out infinite;border:2px solid var(--color-border);border-radius:50%;border-top-color:var(--color-primary);display:inline-block;height:1rem;width:1rem}.spinner-sm{border-width:1px;height:.75rem;width:.75rem}.spinner-md{border-width:2px;height:1rem;width:1rem}.spinner-lg{border-width:3px;height:1.5rem;width:1.5rem}@keyframes spin{to{transform:rotate(1turn)}}@media (max-width:768px){.container{padding:0 var(--spacing-sm)}h1{font-size:var(--font-size-xl)}h2{font-size:var(--font-size-lg)}}@media (prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}