*{box-sizing:border-box}body{margin:0;font-family:Inter,system-ui,sans-serif}#root{min-height:100vh}:root{--primary-color: #646cff;--primary-hover: #535bf2;--background: #ffffff;--surface: #f9f9f9;--text: #213547;--text-secondary: #666;--border: #e0e0e0;--shadow: 0 2px 8px rgba(0,0,0,.1);--shadow-hover: 0 4px 16px rgba(0,0,0,.15);--border-radius: 12px;--spacing: 1rem;--transition-fast: .15s ease;--transition-normal: .3s ease;--transition-slow: .5s ease}.dark-mode{--primary-color: #7c7cff;--primary-hover: #9999ff;--background: #1a1a1a;--surface: #2d2d2d;--text: #ffffff;--text-secondary: #cccccc;--border: #404040;--shadow: 0 2px 8px rgba(0,0,0,.3);--shadow-hover: 0 4px 16px rgba(0,0,0,.4)}.dark-mode .auth-container{background:linear-gradient(135deg,#1a1a1a,#2d1b69)}.dark-mode .auth-card{background:var(--surface);border:1px solid var(--border)}.dark-mode .auth-input,.dark-mode .profile-button{background:var(--background);border-color:var(--border);color:var(--text)}.dark-mode .nav-link{color:var(--text)}.dark-mode .nav-link:hover{background:var(--background)}*{box-sizing:border-box;transition:background-color var(--transition-fast),color var(--transition-fast),border-color var(--transition-fast)}body{margin:0;padding-top:100px;font-family:Inter,system-ui,sans-serif;background:var(--background);color:var(--text)}.container{max-width:1200px;margin:0 auto;padding:0 var(--spacing)}.navbar{position:absolute;top:0;width:100%;z-index:1000;padding:1rem 2rem;background:#fffffff2;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-bottom:1px solid var(--border);box-shadow:var(--shadow)}.navbar-flex{display:flex;align-items:center;justify-content:space-between;width:100%;gap:1.5rem}.navbar-brand{display:flex;align-items:center;gap:.5rem;text-decoration:none;transition:transform var(--transition-normal);flex-direction:row}.navbar-brand:hover{transform:scale(1.05)}.nav-link{display:flex;align-items:center;gap:.5rem;padding:.5rem 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var(--transition-slow)}.btn:hover:before{left:100%}.btn-primary{background:var(--primary-color);color:#fff}.btn-primary:hover{background:var(--primary-hover);transform:translateY(-2px);box-shadow:0 4px 12px #00000026}.btn-secondary{background:var(--surface);color:var(--text);border:1px solid var(--border)}.btn-secondary:hover{background:#f0f0f0;transform:translateY(-1px)}.btn:active{transform:translateY(0)}.card{background:#fff;border-radius:var(--border-radius);box-shadow:var(--shadow);padding:1.5rem;transition:all var(--transition-normal);border:1px solid var(--border)}.card:hover{box-shadow:var(--shadow-hover);transform:translateY(-2px) translateZ(0)}.challenge-card{display:flex;flex-direction:column;align-items:center;text-align:center;cursor:pointer;min-height:280px;max-width:250px;width:100%}.challenge-card img{width:100%;height:180px;object-fit:cover;border-radius:8px;margin-bottom:1rem;transition:transform var(--transition-normal)}.challenge-card:hover img{transform:scale(1.05)}.challenge-title{font-size:1.1rem;font-weight:600;margin-bottom:.5rem}.challenge-meta{font-size:.9rem;color:var(--text-secondary)}.challenges-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:1.5rem;margin-top:2rem}.two-column-layout{display:grid;grid-template-columns:1fr 1fr;gap:2rem;max-width:1200px;margin:2rem auto}.form-container{max-width:400px;margin:2rem auto;padding:2rem;background:#fff;border-radius:var(--border-radius);box-shadow:var(--shadow)}.form-group{margin-bottom:1rem}.form-group label{display:block;margin-bottom:.5rem;font-weight:500}.form-control{width:100%;padding:.75rem;border:1px solid var(--border);border-radius:8px;font-size:1rem;background:var(--background);color:var(--text);transition:all var(--transition-fast)}.form-control:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 0 3px #646cff1a}.skeleton-card{background:#fff;border-radius:var(--border-radius);padding:1.5rem;box-shadow:var(--shadow);animation:pulse 1.5s ease-in-out infinite alternate}.skeleton-image{width:100%;height:180px;background:#e0e0e0;border-radius:8px;margin-bottom:1rem}.skeleton-text{height:16px;background:#e0e0e0;border-radius:4px;margin-bottom:.5rem}.skeleton-title{height:20px;width:80%}.skeleton-meta{height:14px;width:60%}.skeleton-profile{text-align:center;padding:2rem}.skeleton-avatar{width:100px;height:100px;border-radius:50%;background:#e0e0e0;margin:0 auto 1rem}.skeleton-name{width:150px;margin:0 auto .5rem}.toast-container{position:fixed;top:100px;right:20px;z-index:9999;display:flex;flex-direction:column;gap:.5rem}.toast{display:flex;align-items:center;gap:.75rem;padding:1rem 1.5rem;border-radius:var(--border-radius);box-shadow:var(--shadow-hover);cursor:pointer;animation:slideIn .3s 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var(--transition-fast);align-self:flex-end}.clear-all-toasts:hover{background:var(--primary-hover);transform:translateY(-1px)}.search-filter-container{background:#fff;padding:1.5rem;border-radius:var(--border-radius);box-shadow:var(--shadow);margin-bottom:2rem}.search-bar{position:relative;margin-bottom:1rem}.search-input{padding-left:2.5rem}.search-icon{position:absolute;left:.75rem;top:50%;transform:translateY(-50%);color:#666}.filter-controls{display:flex;gap:1rem;align-items:center;flex-wrap:wrap}.filter-select{min-width:150px}.checkbox-label{display:flex;align-items:center;gap:.5rem;cursor:pointer;font-weight:500}.checkbox-label input[type=checkbox]{width:auto}.theme-toggle{background:none;border:2px solid var(--border);border-radius:50%;width:44px;height:44px;display:flex;align-items:center;justify-content:center;cursor:pointer;transition:all var(--transition-normal);margin-left:.5rem}.theme-toggle:hover{border-color:var(--primary-color);transform:rotate(180deg)}.theme-icon{font-size:1.2rem;transition:transform var(--transition-normal)}.theme-toggle:hover .theme-icon{transform:scale(1.1)}.my-profile{background:none;border:none;padding:0;margin-left:1rem}.user-icon{width:32px;height:32px;border-radius:50%;transition:transform var(--transition-fast)}.user-icon:hover{transform:scale(1.1)}.user-avatar{width:36px;height:36px;border-radius:50%;object-fit:cover;border:2px solid var(--primary-color)}.user-name{font-weight:600;font-size:.9rem;display:none}.loading-spinner{width:40px;height:40px;border:4px solid #f3f3f3;border-top:4px solid var(--primary-color);border-radius:50%;animation:spin 1s linear infinite;margin:2rem auto}.fade-in{animation:fadeIn var(--transition-slow) ease-in}.slide-in-left{animation:slideInLeft var(--transition-normal) ease-out}.slide-in-right{animation:slideInRight var(--transition-normal) 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bounceIn{0%{transform:scale(.3);opacity:0}50%{transform:scale(1.05)}70%{transform:scale(.9)}to{transform:scale(1);opacity:1}}@keyframes staggerIn{to{opacity:1;transform:translateY(0)}}@keyframes shake{0%,to{transform:translate(0)}25%{transform:translate(-5px)}75%{transform:translate(5px)}}.dark-mode body{background:var(--background);color:var(--text)}.dark-mode .navbar{background:#2d2d2df2;border-bottom-color:var(--border)}.dark-mode .card{background:var(--surface);border-color:var(--border)}.dark-mode .form-control{background:var(--surface);border-color:var(--border);color:var(--text)}.dark-mode .form-control:focus{border-color:var(--primary-color);box-shadow:0 0 0 3px #7c7cff1a}.dark-mode .btn-secondary{background:var(--surface);color:var(--text);border-color:var(--border)}.dark-mode .btn-secondary:hover,.dark-mode .skeleton-image,.dark-mode .skeleton-text{background:#404040}.dark-mode .search-filter-container{background:var(--surface)}.dark-mode .toast-success{background:#1e4d3a;border-color:#2d5a3d;color:#a3d9b1}.dark-mode .toast-error{background:#4d1e1e;border-color:#5a2d2d;color:#d9a3a3}.dark-mode .toast-warning{background:#4d3d1e;border-color:#5a4a2d;color:#d9c3a3}.dark-mode .toast-info{background:#1e3d4d;border-color:#2d4a5a;color:#a3c3d9}@media (max-width: 480px){.container{padding:0 .5rem}.navbar{padding:1rem;flex-wrap:wrap;gap:.5rem}.navbar-nav{gap:.5rem;flex-wrap:wrap;justify-content:center}.nav-link{display:flex;align-items:center;gap:.5rem;padding:.5rem .75rem;border-radius:var(--border-radius);text-decoration:none;color:var(--text);font-weight:500;font-size:.9rem;transition:all var(--transition-fast);position:relative}.nav-link:hover{background:var(--surface);transform:translateY(-2px)}.nav-link:after{content:"";position:absolute;bottom:0;left:50%;width:0;height:2px;background:var(--primary-color);transition:all var(--transition-normal);transform:translate(-50%)}.nav-link:hover:after{width:80%}.nav-icon{font-size:1.1rem}.user-menu{display:flex;align-items:center;flex-direction:column;gap:.5rem}.profile-button{display:flex;align-items:center;gap:.75rem;background:var(--surface);border:2px solid var(--border);border-radius:50px;padding:.5rem 1rem .5rem .5rem;cursor:pointer;transition:all var(--transition-normal);text-decoration:none;color:var(--text)}.profile-button:hover{border-color:var(--primary-color);transform:translateY(-2px);box-shadow:0 4px 12px #0000001a}.btn{padding:.5rem 1rem;font-size:.9rem}.challenges-grid{grid-template-columns:1fr;gap:1rem}.challenge-card{max-width:100%}@media (max-width: 900px){.three-column-challenges{grid-template-columns:1fr;gap:1.5rem}}.search-filter-container{padding:1rem}.filter-controls{flex-direction:column;gap:.75rem}.form-container{margin:1rem auto;padding:1.5rem}body{padding-top:220px}}.three-column-challenges{display:grid;grid-template-columns:1fr 1fr 1fr;gap:2rem;max-width:1200px;margin:2rem auto;align-items:start}.challenge-column{display:flex;flex-direction:column;gap:1rem;align-items:center}.challenge-header{text-align:center;margin-bottom:1rem;font-size:1.2rem;font-weight:700}@media (min-width: 481px) and (max-width: 768px){.challenges-grid{grid-template-columns:repeat(2,1fr)}.navbar-nav{gap:.75rem}.two-column-layout{grid-template-columns:1fr}.filter-controls{flex-direction:column;align-items:stretch}.filter-select{min-width:auto}}@media (min-width: 769px) and (max-width: 1024px){.challenges-grid{grid-template-columns:repeat(3,1fr)}}@media (min-width: 1025px){.challenges-grid{grid-template-columns:repeat(auto-fill,minmax(250px,1fr))}}@media (max-width: 768px){.auth-card{padding:2rem 1.5rem;margin:1rem}.stagger-item{animation:none;opacity:1;transform:none}.card:hover{transform:none}}@media (prefers-reduced-motion: reduce){*{animation:none!important;transition:none!important}}img{max-width:100%;height:auto}.auth-container{min-height:calc(100vh - 80px);display:flex;align-items:center;justify-content:center;background:linear-gradient(135deg,var(--primary-color) 0%,#9333ea 100%);padding:2rem 1rem}.auth-card{background:#fff;border-radius:20px;box-shadow:0 20px 40px #0000001a;padding:3rem;width:100%;max-width:450px;animation:slideUp .6s ease-out}.auth-header{text-align:center;margin-bottom:2rem}.auth-title{font-size:1.5rem;font-weight:700;color:var(--text);margin-bottom:.5rem;background:linear-gradient(135deg,var(--primary-color),#9333ea);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.auth-subtitle{color:var(--text-secondary);font-size:1rem;margin:0}.auth-form{margin-bottom:2rem}.auth-buttons{display:flex;align-items:center;gap:.75rem}.btn-outline{background:transparent;color:var(--text);border:2px solid var(--border)}.btn-outline:hover{background:var(--surface);border-color:var(--primary-color);color:var(--primary-color)}.logout-btn{font-size:.9rem;padding:.5rem 1rem}.input-wrapper{position:relative;margin-bottom:1rem}.input-icon{position:absolute;left:1rem;top:50%;transform:translateY(-50%);font-size:1.2rem;z-index:2}.auth-input{padding-left:3rem!important;height:3rem;border:2px solid var(--border);transition:all var(--transition-normal);font-size:1rem}.auth-input:focus{border-color:var(--primary-color);box-shadow:0 0 0 4px #646cff1a;transform:translateY(-2px)}.auth-submit{width:100%;height:3rem;font-size:1.1rem;font-weight:600;margin-top:1rem;position:relative;overflow:hidden}.auth-submit.loading{pointer-events:none}.spinner{width:20px;height:20px;border:2px solid transparent;border-top:2px solid currentColor;border-radius:50%;animation:spin 1s linear infinite;margin-right:.5rem;display:inline-block}.auth-footer{text-align:center;padding-top:1rem;border-top:1px solid var(--border)}.link-button{background:none;border:none;color:var(--primary-color);font-weight:600;cursor:pointer;text-decoration:underline;margin-left:.5rem;transition:color var(--transition-fast)}.link-button:hover{color:var(--primary-hover)}@keyframes slideUp{0%{opacity:0;transform:translateY(30px)}to{opacity:1;transform:translateY(0)}}.about-container{display:flex;justify-content:center;align-items:flex-start;min-height:60vh;padding:2rem 1rem}.about-card{background:var(--surface);border-radius:var(--border-radius);box-shadow:var(--shadow);padding:2.5rem 2rem;max-width:1000px;width:100%;border:1px solid var(--border);animation:fadeIn .7s}.about-title{font-size:2rem;font-weight:700;margin-bottom:1.5rem;text-align:center;letter-spacing:-1px}.about-list{list-style:disc inside;color:var(--text-secondary);font-size:1.1rem;margin-bottom:2rem;padding-left:1rem}.about-list li{margin-bottom:.75rem;line-height:1.6}.about-contact{text-align:center;font-size:1rem;color:var(--primary-color);margin-top:1.5rem;font-weight:500}.dark-mode .about-card{background:var(--surface);color:var(--text);border-color:var(--border)}.dark-mode .about-list{color:var(--text-secondary)}