.flashcard-heatmap{background:linear-gradient(135deg,#1e1e1e,#252525);border:1px solid #333;border-radius:20px;padding:40px;color:#fff;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;margin:40px auto;max-width:1400px;width:100%;position:relative;overflow:hidden;box-shadow:0 8px 32px rgba(0,0,0,.3);animation:fadeInUp .6s ease-out .3s both;box-sizing:border-box}@keyframes fadeInUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}.flashcard-heatmap:before{content:"";position:absolute;top:0;left:0;right:0;height:4px;background:linear-gradient(135deg,#4facfe,#00f2fe);opacity:0;transition:opacity .3s ease}.flashcard-heatmap:hover:before{opacity:1}.heatmap-header{display:flex;justify-content:space-between;align-items:flex-start;margin-bottom:40px;flex-wrap:wrap;gap:30px;padding:0}.heatmap-title-section{display:flex;flex-direction:column;gap:16px;padding:0}.heatmap-title-section h3{margin:0;font-size:1.6rem;font-weight:700;color:#fff;display:flex;align-items:center;gap:12px;background:linear-gradient(135deg,#4facfe,#00f2fe);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;padding:0}.loading-indicator{font-size:1.2rem;animation:spin 1s linear infinite;color:#4facfe;-webkit-text-fill-color:#4facfe}@keyframes spin{0%{transform:rotate(0deg)}to{transform:rotate(1turn)}}.total-reviews{font-size:1rem;color:#aaa;font-weight:500;letter-spacing:.5px;padding:0;margin:0}.year-navigation{gap:12px;background:rgba(0,0,0,.4);border-radius:16px;padding:12px;border:1px solid rgba(79,172,254,.2);backdrop-filter:blur(10px)}.year-nav-btn,.year-navigation{display:flex;align-items:center}.year-nav-btn{background:rgba(79,172,254,.1);border:2px solid rgba(79,172,254,.3);color:#4facfe;border-radius:12px;width:40px;height:40px;justify-content:center;cursor:pointer;font-size:1.2rem;font-weight:700;transition:all .3s ease;position:relative;overflow:hidden}.year-nav-btn:before{content:"";position:absolute;top:50%;left:50%;width:0;height:0;background:rgba(79,172,254,.2);border-radius:50%;transition:all .4s ease;transform:translate(-50%,-50%)}.year-nav-btn:hover:not(:disabled):before{width:60px;height:60px}.year-nav-btn:hover:not(:disabled){background:rgba(79,172,254,.2);border-color:rgba(79,172,254,.6);transform:translateY(-2px);box-shadow:0 4px 15px rgba(79,172,254,.3)}.year-nav-btn:disabled{opacity:.3;cursor:not-allowed;transform:none}.year-select{background:rgba(30,30,30,.9);border:2px solid #444;color:#fff;border-radius:12px;padding:12px 40px 12px 20px;font-size:1rem;font-weight:700;cursor:pointer;transition:all .3s ease;-webkit-appearance:none;-moz-appearance:none;appearance:none;min-width:100px;text-align:center;position:relative;background-image:url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%234facfe' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='M6 8l4 4 4-4'/%3e%3c/svg%3e");background-position:right 12px center;background-repeat:no-repeat;background-size:16px}.year-select:focus{outline:none;border-color:#4facfe;box-shadow:0 0 0 3px rgba(79,172,254,.2)}.year-select:hover{border-color:#4facfe;background:#1e1e1e;transform:translateY(-1px)}.year-select option{background:#1e1e1e;color:#fff;padding:8px}.heatmap-error{text-align:center;padding:60px 20px;color:#ff6b6b;background:hsla(0,100%,71%,.05);border-radius:16px;border:1px solid hsla(0,100%,71%,.2)}.heatmap-error p{margin:0 0 20px;font-size:1.1rem;font-weight:500}.retry-button{background:hsla(0,100%,71%,.1);border:2px solid hsla(0,100%,71%,.3);color:#ff6b6b;border-radius:12px;padding:12px 24px;cursor:pointer;transition:all .3s ease;font-weight:600;font-size:1rem}.retry-button:hover{background:hsla(0,100%,71%,.2);transform:translateY(-2px);box-shadow:0 4px 15px hsla(0,100%,71%,.3)}.heatmap-loading{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:60px 20px;text-align:center}.loading-spinner{width:40px;height:40px;border:4px solid #333;border-top-color:#4facfe;border-radius:50%;animation:spin 1s linear infinite;margin-bottom:20px}.heatmap-loading p{color:#aaa;margin:0;font-size:1rem;font-weight:500}.heatmap-grid{margin-bottom:40px;position:relative;width:100%;background:rgba(0,0,0,.2);border-radius:16px;padding:30px;border:1px solid hsla(0,0%,100%,.1)}.heatmap-main-grid{display:grid;grid-template-columns:80px 1fr;gap:20px;align-items:start;width:100%;overflow-x:auto;scrollbar-width:thin;scrollbar-color:#4facfe transparent}.heatmap-main-grid::-webkit-scrollbar{height:8px}.heatmap-main-grid::-webkit-scrollbar-track{background:rgba(0,0,0,.2);border-radius:4px}.heatmap-main-grid::-webkit-scrollbar-thumb{background:#4facfe;border-radius:4px}.heatmap-main-grid::-webkit-scrollbar-thumb:hover{background:#00f2fe}.day-labels{display:grid;grid-template-rows:16px repeat(7,16px);gap:2px;width:80px;justify-self:end;align-items:center;text-align:right;margin-top:12px}.day-labels .spacer{grid-row:1;height:16px}.day-labels span{font-size:.8rem;color:#888;font-weight:600;text-transform:uppercase;letter-spacing:.5px;padding-right:8px;height:16px;display:flex;align-items:center;justify-content:flex-end}.heatmap-months-container{display:flex;gap:20px;align-items:start;overflow-x:auto;scrollbar-width:thin;scrollbar-color:#4facfe transparent}.heatmap-months-container::-webkit-scrollbar{height:8px}.heatmap-months-container::-webkit-scrollbar-track{background:rgba(0,0,0,.2);border-radius:4px}.heatmap-months-container::-webkit-scrollbar-thumb{background:#4facfe;border-radius:4px}.heatmap-months-container::-webkit-scrollbar-thumb:hover{background:#00f2fe}.heatmap-month-group{display:flex;flex-direction:column;align-items:center;flex-shrink:0}.month-label-vertical{font-size:.8rem;color:#888;font-weight:600;text-transform:uppercase;letter-spacing:.6px;text-align:center;margin-bottom:8px;height:16px;padding:6px 0;display:flex;align-items:center;justify-content:center;transition:color .3s ease;-webkit-user-select:none;-moz-user-select:none;user-select:none}.month-label-vertical:hover{color:#4facfe}.heatmap-month-weeks{display:flex;gap:4px;flex-shrink:0}.heatmap-week{display:flex;flex-direction:column;gap:2px;min-width:16px}.heatmap-day{width:16px;height:16px;border-radius:3px;cursor:pointer;position:relative;display:flex;align-items:center;justify-content:center;font-size:7px;font-weight:700;transition:all .2s ease;box-sizing:border-box;flex-shrink:0}.heatmap-day.empty{background:transparent;cursor:default;pointer-events:none}.heatmap-day[data-level="0"]{background-color:#2d2d2d;border:1px solid #3a3a3a;color:#666}.heatmap-day[data-level="1"]{background-color:#0e4429;border:1px solid #0e4429;color:#fff}.heatmap-day[data-level="2"]{background-color:#006d32;border:1px solid #006d32;color:#fff}.heatmap-day[data-level="3"]{background-color:#26a641;border:1px solid #26a641;color:#fff}.heatmap-day[data-level="4"]{background-color:#39d353;border:1px solid #39d353;color:#000}.heatmap-day[data-today=true]{border:2px solid #4facfe!important;box-shadow:0 0 8px rgba(79,172,254,.6)}.heatmap-day[data-level]:not(.empty):hover{transform:scale(1.3);border:2px solid #4facfe!important;z-index:10;box-shadow:0 2px 8px rgba(79,172,254,.4)}.day-count{font-size:6px;font-weight:700;opacity:.9;pointer-events:none;position:absolute;-webkit-user-select:none;-moz-user-select:none;user-select:none}.heatmap-stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:24px;margin-bottom:32px;padding:32px 28px;background:linear-gradient(135deg,rgba(79,172,254,.1),rgba(0,242,254,.05));border-radius:16px;border:1px solid rgba(79,172,254,.2);backdrop-filter:blur(10px)}.stat-item{text-align:center;transition:all .3s ease;padding:20px 16px;border-radius:12px;background:rgba(0,0,0,.2);border:1px solid hsla(0,0%,100%,.1);position:relative;overflow:hidden}.stat-item:before{content:"";position:absolute;top:0;left:0;right:0;height:3px;background:linear-gradient(135deg,#4facfe,#00f2fe);opacity:0;transition:opacity .3s ease}.stat-item:hover:before{opacity:1}.stat-item:hover{transform:translateY(-4px);box-shadow:0 8px 25px rgba(79,172,254,.2);border-color:rgba(79,172,254,.3)}.stat-value{font-size:2rem;font-weight:800;color:#4facfe;margin-bottom:12px;text-shadow:0 0 15px rgba(79,172,254,.4);background:linear-gradient(135deg,#4facfe,#00f2fe);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.stat-label{font-size:.8rem;color:#ccc;text-transform:uppercase;letter-spacing:1px;font-weight:600;margin:0}.heatmap-legend{display:flex;align-items:center;justify-content:center;gap:16px;opacity:.9;background:rgba(0,0,0,.3);padding:20px 28px;border-radius:12px;border:1px solid hsla(0,0%,100%,.1);margin-top:16px}.legend-text{font-size:.8rem;color:#888;font-weight:600;text-transform:uppercase;letter-spacing:.5px}.legend-squares{display:flex;gap:4px}.legend-square{width:16px;height:16px;border-radius:3px;transition:all .2s ease;cursor:pointer}.legend-square:hover{transform:scale(1.3);box-shadow:0 2px 8px rgba(79,172,254,.4)}.legend-square.level-0{background-color:#2d2d2d;border:1px solid #3a3a3a}.legend-square.level-1{background-color:#0e4429}.legend-square.level-2{background-color:#006d32}.legend-square.level-3{background-color:#26a641}.legend-square.level-4{background-color:#39d353}@media (max-width:768px){.flashcard-heatmap{padding:28px 24px;margin:30px auto;width:100%}.heatmap-header{flex-direction:column;align-items:flex-start;gap:20px;margin-bottom:30px}.heatmap-title-section{align-self:stretch;gap:12px}.year-navigation{align-self:center}.heatmap-header h3{font-size:1.3rem;gap:8px}.total-reviews{font-size:.9rem}.heatmap-main-grid{grid-template-columns:60px 1fr;gap:16px}.day-labels{width:60px;grid-template-rows:32px repeat(7,12px)}.day-labels span{font-size:.7rem;height:12px;padding-right:4px}.heatmap-months-container{gap:16px}.month-label-vertical{font-size:.7rem;margin-bottom:12px;height:16px;padding:8px 0}.heatmap-day{width:12px;height:12px}.heatmap-week{min-width:12px}.heatmap-stats{grid-template-columns:repeat(2,1fr);padding:24px 20px;gap:20px;margin-bottom:24px}.stat-item{padding:16px 12px}.stat-value{font-size:1.6rem;margin-bottom:8px}.legend-text,.stat-label{font-size:.75rem}.legend-square{width:12px;height:12px}.year-nav-btn{width:36px;height:36px;font-size:1rem}.year-select{padding:10px 32px 10px 16px;font-size:.9rem;min-width:90px}.heatmap-legend{padding:16px 20px;gap:12px;margin-top:12px}.heatmap-grid{padding:24px 20px;margin-bottom:30px}}@media (max-width:480px){.flashcard-heatmap{padding:24px 20px;margin:20px auto;width:100%}.heatmap-header{gap:16px;margin-bottom:24px}.heatmap-header h3{font-size:1.1rem;gap:6px}.total-reviews{font-size:.85rem}.heatmap-title-section{gap:8px}.heatmap-main-grid{grid-template-columns:50px 1fr;gap:12px}.day-labels{width:50px;grid-template-rows:28px repeat(7,10px)}.day-labels span{font-size:.65rem;height:10px;padding-right:2px}.heatmap-months-container{gap:12px}.month-label-vertical{font-size:.65rem;margin-bottom:10px;height:14px;padding:6px 0}.heatmap-day{width:10px;height:10px}.heatmap-week{min-width:10px}.heatmap-stats{grid-template-columns:1fr;gap:16px;padding:20px 16px;margin-bottom:20px}.stat-item{display:flex;justify-content:space-between;align-items:center;text-align:left;padding:16px 20px}.stat-value{font-size:1.4rem;margin-bottom:0}.stat-label{font-size:.8rem;text-transform:none;letter-spacing:normal}.year-navigation{padding:8px;gap:8px}.year-nav-btn{width:32px;height:32px;font-size:.9rem}.year-select{padding:8px 28px 8px 12px;font-size:.8rem;min-width:80px}.heatmap-legend{padding:14px 16px;gap:10px;margin-top:10px}.heatmap-grid{padding:20px 16px;margin-bottom:24px}.legend-squares{gap:3px}.legend-square{width:10px;height:10px}}@media (prefers-contrast:high){.heatmap-day[data-level="0"]{background:#000;border:2px solid #666}.heatmap-day[data-level="1"]{background:#030;border:1px solid #666}.heatmap-day[data-level="2"]{background:#060;border:1px solid #666}.heatmap-day[data-level="3"]{background:#090;border:1px solid #666}.heatmap-day[data-level="4"]{background:#0c0;border:1px solid #000}.year-nav-btn,.year-select{border:2px solid #4facfe}}@media (prefers-reduced-motion:reduce){.flashcard-heatmap,.heatmap-day,.legend-square,.loading-indicator,.loading-spinner,.stat-item,.year-nav-btn{animation:none;transition:none}.flashcard-heatmap:hover,.heatmap-day:hover,.stat-item:hover,.year-nav-btn:hover{transform:none}}