:root{--primary:#2563eb;--primary-hover:#1d4ed8;--primary-light:#dbeafe;--success:#16a34a;--success-light:#dcfce7;--warning:#f59e0b;--warning-light:#fef3c7;--danger:#dc2626;--danger-light:#fee2e2;--text-primary:#1e293b;--text-secondary:#64748b;--text-muted:#94a3b8;--border:#e2e8f0;--bg-primary:#fff;--bg-secondary:#f8fafc;--bg-tertiary:#f1f5f9;--go-board:#d4c4a8;--go-board-dark:#c4b498;--spacing-1:4px;--spacing-2:8px;--spacing-3:12px;--spacing-4:16px;--spacing-5:20px;--spacing-6:24px;--spacing-8:32px;--spacing-12:48px;--radius-sm:4px;--radius-md:8px;--radius-lg:12px;--radius-xl:16px;--font-xs:11px;--font-sm:12px;--font-base:14px;--font-md:15px;--font-lg:16px;--font-xl:18px;--font-2xl:20px;--font-3xl:24px;--font-4xl:28px}*{margin:0;padding:0;box-sizing:border-box}body{font-family:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Microsoft YaHei',Roboto,sans-serif;background-color:var(--bg-secondary);color:var(--text-primary);line-height:1.6;min-height:100vh;display:flex;flex-direction:column}a{color:var(--primary);text-decoration:none}a:hover{text-decoration:underline}.mt-1{margin-top:var(--spacing-1)}.mt-2{margin-top:var(--spacing-2)}.mt-3{margin-top:var(--spacing-3)}.mt-4{margin-top:var(--spacing-4)}.mt-6{margin-top:var(--spacing-6)}.mt-8{margin-top:var(--spacing-8)}.mb-1{margin-bottom:var(--spacing-1)}.mb-2{margin-bottom:var(--spacing-2)}.mb-3{margin-bottom:var(--spacing-3)}.mb-4{margin-bottom:var(--spacing-4)}.mb-6{margin-bottom:var(--spacing-6)}.mb-8{margin-bottom:var(--spacing-8)}.text-center{text-align:center}.text-muted{color:var(--text-muted)}.text-secondary{color:var(--text-secondary)}.text-primary{color:var(--primary)}.text-success{color:var(--success)}.text-warning{color:var(--warning)}.text-danger{color:var(--danger)}.flex{display:flex}.flex-between{display:flex;justify-content:space-between;align-items:center}.flex-center{display:flex;justify-content:center;align-items:center}.flex-column{display:flex;flex-direction:column}.grid{display:grid}.flex-between{display:flex;justify-content:space-between;align-items:center}.mb-8{margin-bottom:var(--spacing-2)}.mb-12{margin-bottom:var(--spacing-3)}.mb-16{margin-bottom:var(--spacing-4)}.mb-24{margin-bottom:var(--spacing-6)}.mt-8{margin-top:var(--spacing-2)}.mt-12{margin-top:var(--spacing-3)}.mt-16{margin-top:var(--spacing-4)}.mt-24{margin-top:var(--spacing-6)}.error-page{display:flex;align-items:center;justify-content:center;min-height:calc(100vh - 200px);padding:40px 20px}.error-card{max-width:480px;width:100%;text-align:center}.error-icon{font-size:64px;margin-bottom:12px}.error-code{font-size:72px;font-weight:800;color:var(--text-muted);margin:0;line-height:1}.error-title{font-size:22px;font-weight:700;color:var(--text-primary);margin:12px 0 8px}.error-detail{color:var(--text-secondary);font-size:14px;margin:0 0 28px;line-height:1.6}.error-actions{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}#langDropdownMenu a:hover{text-decoration:none}.logo-color{background:linear-gradient(135deg,#2563EB 0,#4F46E5 50%,#7C3AED 100%);background-clip:text;-webkit-background-clip:text;-webkit-text-fill-color:transparent}.container{max-width:1400px;margin:0 auto;padding:0 var(--spacing-5)}header{background-color:var(--bg-primary);border-bottom:1px solid var(--border);padding:var(--spacing-3) 0;position:sticky;top:0;z-index:1000}.header-content{display:flex;justify-content:space-between;align-items:center;gap:var(--spacing-8)}.logo{display:flex;align-items:center;gap:var(--spacing-2);font-size:22px;font-weight:700;color:var(--text-primary);text-decoration:none;flex-shrink:0}.logo:hover{text-decoration:none}.logo-icon{width:45px;height:45px}.nav-links{display:flex;gap:var(--spacing-8);align-items:center;margin-right:auto;padding-top:5px}.nav-links a{text-decoration:none;color:var(--text-secondary);font-weight:500;font-size:var(--font-base);transition:color .2s}.nav-links a:hover{color:var(--text-primary);text-decoration:none}.nav-links a.active{color:var(--text-primary)}.auth-section{display:flex;gap:var(--spacing-3);align-items:center}.auth-section .user-name{font-weight:600;font-size:var(--font-sm);color:var(--text-primary)}.auth-section .btn{padding:7px 12px;font-size:var(--font-sm);display:inline-flex;align-items:center}main{flex:1}.main-content{display:flex;gap:var(--spacing-6);padding:var(--spacing-6) 0}.content-left{flex:2;min-width:0}.content-right{flex:1;min-width:300px}.feature-buttons{display:grid;grid-template-columns:repeat(4,1fr);gap:var(--spacing-4);margin-bottom:var(--spacing-6)}.problems-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:var(--spacing-4)}footer{background-color:var(--bg-secondary);border-top:1px solid var(--border);padding:var(--spacing-5) 0;margin-top:auto}.footer-content{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:var(--spacing-4)}.footer-links{display:flex;gap:var(--spacing-8)}.footer-links a{color:var(--text-secondary);text-decoration:none;font-size:var(--font-base)}.footer-links a:hover{color:var(--text-primary)}.social-links{display:flex;gap:var(--spacing-3)}.social-icon{width:32px;height:32px;background-color:var(--border);border-radius:50%;display:flex;align-items:center;justify-content:center;color:var(--text-secondary)}.copyright{color:var(--text-secondary);font-size:var(--font-sm)}.hero-banner{background:linear-gradient(135deg,#667eea 0,#764ba2 100%);border-radius:var(--radius-xl);overflow:hidden;box-shadow:0 1px 3px rgba(0,0,0,0.1);margin-bottom:var(--spacing-6);display:flex;align-items:center;justify-content:center;min-height:200px;color:white;padding:var(--spacing-12) var(--spacing-5);text-align:center}.hero-banner h2{font-size:var(--font-4xl);font-weight:700;margin-bottom:var(--spacing-2)}.hero-banner p{font-size:var(--font-lg);opacity:.9}.hamburger-btn{display:none;background:none;border:none;cursor:pointer;padding:4px;color:var(--text-primary);z-index:1001}.hamburger-btn svg{display:block}.hamburger-btn.active .hamburger-icon{display:none}.hamburger-btn.active .close-icon{display:block!important}.mobile-menu{display:none;position:absolute;top:100%;left:0;right:0;background:var(--bg-primary);border-bottom:1px solid var(--border);box-shadow:0 8px 16px rgba(0,0,0,0.1);padding:var(--spacing-4);z-index:999}.mobile-menu.show{display:block}.mobile-nav-links{display:flex;flex-direction:column;gap:var(--spacing-2);margin-bottom:var(--spacing-4);padding-bottom:var(--spacing-4);border-bottom:1px solid var(--border)}.mobile-nav-links a{display:block;padding:var(--spacing-2) 0;color:var(--text-primary);text-decoration:none;font-size:var(--font-base);font-weight:500}.mobile-nav-links a:hover{color:var(--primary)}.mobile-auth{display:flex;flex-direction:column;gap:var(--spacing-2)}.mobile-auth .btn{text-align:center}.mobile-user{display:flex;align-items:center;gap:8px;padding:var(--spacing-2) 0;color:var(--text-primary);text-decoration:none;font-weight:600;font-size:var(--font-base)}.mobile-lang{display:flex;align-items:center;gap:var(--spacing-3);margin-top:var(--spacing-4);padding-top:var(--spacing-4);border-top:1px solid var(--border)}.mobile-lang-label{font-size:var(--font-base)}.mobile-lang-link{font-size:var(--font-sm);color:var(--text-secondary);text-decoration:none;cursor:pointer;padding:4px 10px;border-radius:var(--radius-md);transition:all .15s}.mobile-lang-link:hover{background:var(--bg-secondary);color:var(--text-primary)}.mobile-lang-link.active{color:var(--primary);font-weight:600;background:var(--primary-light)}@media(max-width:1024px){.main-content{flex-direction:column}.content-right{min-width:0}.feature-buttons{grid-template-columns:repeat(2,1fr)}.problems-grid{grid-template-columns:repeat(3,1fr)}}@media(max-width:900px){.nav-links,.auth-section{display:none}.hamburger-btn{display:inline-flex;align-items:center;justify-content:center}.header-content{flex-wrap:wrap;gap:var(--spacing-3)}}@media(max-width:640px){.feature-buttons{grid-template-columns:1fr}.problems-grid{grid-template-columns:repeat(2,1fr)}}.btn{padding:var(--spacing-3) var(--spacing-5);border-radius:var(--radius-md);font-weight:600;font-size:var(--font-base);cursor:pointer;transition:all .2s;border:none;text-decoration:none;display:inline-block}.btn-primary{background-color:var(--primary);color:white}.btn-primary:hover{background-color:var(--primary-hover);text-decoration:none}.btn-secondary{background-color:#e5e7eb;color:var(--text-primary)}.btn-secondary:hover{background-color:#d1d5db}.btn-success{background-color:var(--success);color:white}.btn-success:hover{background-color:#15803d}.btn-danger{background-color:var(--danger);color:white}.btn-danger:hover{background-color:#b91c1c}.btn-sm{padding:var(--spacing-1) var(--spacing-3);font-size:var(--font-sm)}.card{background-color:var(--bg-primary);border-radius:var(--radius-xl);padding:var(--spacing-6);box-shadow:0 1px 3px rgba(0,0,0,0.1)}.page-section{background:var(--bg-primary);border-radius:var(--radius-xl);padding:var(--spacing-6);box-shadow:0 1px 3px rgba(0,0,0,0.1)}.page-section__header{display:flex;justify-content:space-between;align-items:center;margin-bottom:var(--spacing-4)}.page-section__title{font-weight:600;font-size:var(--font-xl);color:var(--text-primary)}.page-section__desc{color:var(--text-secondary);font-size:var(--font-base);margin-bottom:var(--spacing-4)}.feature-card{background-color:var(--bg-primary);border-radius:var(--radius-xl);padding:var(--spacing-6);box-shadow:0 1px 3px rgba(0,0,0,0.1);cursor:pointer;transition:all .2s;display:flex;align-items:center;gap:var(--spacing-4);text-decoration:none;color:inherit}.feature-card:hover{transform:translateY(-2px);box-shadow:0 4px 12px rgba(0,0,0,0.15);text-decoration:none;color:inherit}.feature-icon{width:48px;height:48px;border-radius:var(--radius-lg);display:flex;align-items:center;justify-content:center;font-size:24px;flex-shrink:0}.feature-card:nth-child(1) .feature-icon{background-color:var(--primary-light);color:var(--primary)}.feature-card:nth-child(2) .feature-icon{background-color:var(--success-light);color:var(--success)}.feature-card:nth-child(3) .feature-icon{background-color:#f3e8ff;color:#9333ea}.feature-card:nth-child(4) .feature-icon{background-color:#ffedd5;color:#ea580c}.feature-text h3{font-size:var(--font-md);font-weight:600;color:var(--text-primary)}.feature-text p{font-size:var(--font-sm);color:var(--text-secondary);margin-top:var(--spacing-1)}.problem-card{background-color:var(--bg-secondary);border-radius:var(--radius-lg);padding:var(--spacing-3);cursor:pointer;transition:all .2s;border:1px solid var(--border);text-decoration:none;color:inherit;display:flex;flex-direction:column}.problem-card:hover{border-color:var(--primary);text-decoration:none;color:inherit}.problem-img{position:relative;aspect-ratio:1;background:linear-gradient(135deg,var(--go-board) 0,var(--go-board-dark) 100%);border-radius:var(--radius-md);margin-bottom:var(--spacing-3);display:flex;align-items:center;justify-content:center;font-size:40px}.board-svg{width:100%;height:100%;object-fit:cover;border-radius:var(--radius-md)}.problem-info{padding-top:var(--spacing-1)}.problem-number{font-size:var(--font-sm);font-weight:600;color:var(--text-primary);overflow:hidden;display:-webkit-box;line-clamp:2;-webkit-box-orient:vertical;white-space:normal;line-height:1.3;text-align:center}.badge{display:inline-block;padding:var(--spacing-1) var(--spacing-2);border-radius:var(--radius-sm);font-size:var(--font-xs);font-weight:600}.badge--success{background:var(--success);color:white}.badge--warning{background:var(--warning);color:white}.badge--danger{background:var(--danger);color:white}.badge--primary{background:var(--primary);color:white}.difficulty-badge{position:absolute;top:var(--spacing-1);right:var(--spacing-1);display:inline-block;padding:var(--spacing-1) var(--spacing-2);background-color:var(--success);color:white;border-radius:var(--radius-sm);font-size:var(--font-xs);font-weight:600}.rank-tooltip{position:absolute;bottom:100%;left:50%;transform:translateX(-50%);background:#333;color:#fff;padding:var(--spacing-1) var(--spacing-2);border-radius:var(--radius-md);font-size:var(--font-sm);white-space:nowrap;opacity:0;visibility:hidden;transition:all .2s;margin-bottom:var(--spacing-1);z-index:100}.rank-tooltip::after{content:'';position:absolute;top:100%;left:50%;transform:translateX(-50%);border:5px solid transparent;border-top-color:#333}.difficulty-badge:hover .rank-tooltip{opacity:1;visibility:visible}.sidebar-card{background-color:var(--bg-primary);border-radius:var(--radius-xl);padding:var(--spacing-6);box-shadow:0 1px 3px rgba(0,0,0,0.1);margin-bottom:var(--spacing-6)}.progress-card{text-align:center;padding:var(--spacing-12) var(--spacing-6)}.progress-icon{width:90px;height:90px;background:linear-gradient(135deg,#fef3c7 0,#fde68a 100%);border-radius:50%;display:flex;align-items:center;justify-content:center;margin:0 auto var(--spacing-5);font-size:36px}.progress-card h3{font-size:var(--font-2xl);font-weight:600;margin-bottom:var(--spacing-2)}.progress-card p{color:var(--text-secondary);font-size:var(--font-base);margin-bottom:var(--spacing-5)}.progress-stats{display:grid;grid-template-columns:1fr 1fr;gap:var(--spacing-3);margin-bottom:var(--spacing-4)}.progress-stat{background:var(--bg-secondary);border-radius:var(--radius-lg);padding:var(--spacing-4) var(--spacing-3);text-align:center}.progress-stat .stat-value{font-size:var(--font-3xl);font-weight:700;color:var(--primary)}.progress-stat .stat-label{font-size:var(--font-xs);color:var(--text-secondary);margin-top:var(--spacing-1)}.progress-bar{width:100%;height:12px;background-color:var(--border);border-radius:var(--radius-md);overflow:hidden}.progress-bar .fill{height:100%;background:linear-gradient(90deg,#667eea 0,#764ba2 100%);transition:width .3s ease}.alert{padding:var(--spacing-2) var(--spacing-3);border-radius:var(--radius-sm);font-size:var(--font-sm);margin-bottom:var(--spacing-2)}.alert-error{background:var(--danger-light);color:#b91c1c}.alert-success{background:var(--success-light);color:var(--success)}.alert-info{background:var(--primary-light);color:var(--primary)}.form-group{margin-bottom:var(--spacing-4)}.form-group label{display:block;font-size:var(--font-base);font-weight:500;margin-bottom:var(--spacing-2);color:var(--text-primary)}.form-group input{width:100%;padding:var(--spacing-3);border:1px solid var(--border);border-radius:var(--radius-md);font-size:var(--font-base)}.form-group input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,0.1)}.login-form h3{font-size:var(--font-xl);font-weight:600;margin-bottom:var(--spacing-2)}.login-form p{color:var(--text-secondary);font-size:var(--font-base);margin-bottom:var(--spacing-5)}.divider{display:flex;align-items:center;gap:var(--spacing-3);margin:var(--spacing-5) 0}.divider::before,.divider::after{content:'';flex:1;height:1px;background-color:var(--border)}.divider span{color:var(--text-secondary);font-size:var(--font-sm)}.signup-link{text-align:center;margin-top:var(--spacing-5);font-size:var(--font-base);color:var(--text-secondary)}.signup-link a{color:var(--primary);font-weight:500;text-decoration:none}.pagination{display:flex;gap:var(--spacing-2);justify-content:center;margin-top:var(--spacing-6);flex-wrap:wrap}.pagination a,.pagination span{display:inline-flex;align-items:center;justify-content:center;padding:var(--spacing-2) var(--spacing-4);border-radius:var(--radius-md);font-size:var(--font-base);text-decoration:none;border:1px solid var(--border);color:var(--text-primary);background:var(--bg-primary);transition:all .2s}.pagination a:hover{border-color:var(--primary);background:#fdf6ec;color:var(--primary)}.pagination .active{border-color:var(--primary);background:var(--primary);color:white}.pagination .disabled{opacity:.5;cursor:not-allowed}.tag{display:inline-block;padding:var(--spacing-1) var(--spacing-2);background-color:var(--bg-tertiary);color:var(--text-secondary);border-radius:var(--radius-sm);font-size:var(--font-sm);margin-left:var(--spacing-2)}.tag-level{display:inline-block;padding:var(--spacing-1) var(--spacing-2);background-color:var(--primary-light);color:var(--primary);border-radius:var(--radius-sm);font-size:var(--font-sm);font-weight:600;margin-right:var(--spacing-2)}.daily-list{display:flex;flex-direction:column;gap:var(--spacing-2)}.daily-row{display:flex;align-items:center;justify-content:space-between;padding:var(--spacing-3) var(--spacing-4);border:1px solid var(--border);border-radius:var(--radius-md);background:var(--bg-primary);transition:all .15s}.daily-row:hover{border-color:var(--primary);background:var(--primary-light)}.daily-row .num{width:32px;font-weight:700;color:var(--primary);font-size:var(--font-base)}.daily-row .info{flex:1}.daily-row .info .desc{font-weight:500;font-size:var(--font-base)}.daily-row .info .meta{font-size:var(--font-sm);color:var(--text-secondary);margin-top:var(--spacing-1)}.board-placeholder{background:linear-gradient(135deg,var(--go-board) 0,var(--go-board-dark) 100%);border-radius:var(--radius-lg);aspect-ratio:1;display:flex;align-items:center;justify-content:center}.lang-dropdown{position:relative;display:inline-block}.lang-dropdown__btn{display:flex;align-items:center;gap:6px;padding:7px 10px;background:#e5e7eb;border:none;border-radius:var(--radius-md);font-size:var(--font-sm);font-weight:500;color:var(--text-primary);cursor:pointer;transition:all .2s}.lang-dropdown__btn:hover{background:#d1d5db}.lang-dropdown__arrow{font-size:10px;transition:transform .2s}.lang-dropdown__menu{position:absolute;top:100%;right:0;margin-top:4px;min-width:100%;width:100%;background:var(--bg-primary);border:1px solid var(--border);border-radius:var(--radius-md);box-shadow:0 4px 12px rgba(0,0,0,0.12);opacity:0;visibility:hidden;transform:translateY(-4px);transition:all .15s;z-index:1000;overflow:hidden}.lang-dropdown__menu.show{opacity:1;visibility:visible;transform:translateY(0)}.lang-dropdown__item{display:block;padding:10px 14px;font-size:var(--font-sm);color:var(--text-primary);text-decoration:none;transition:background .15s;cursor:pointer;text-align:center}.lang-dropdown__item:hover{background:var(--bg-secondary)}.lang-dropdown__item--active{color:var(--primary);font-weight:600;background:var(--primary-light)}.lang-dropdown__item--active:hover{background:var(--primary-light)}.practice-header{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:var(--spacing-3)}.practice-header h2{margin:0}.practice-header-actions{display:flex;gap:var(--spacing-2);align-items:center}.modal-overlay{position:fixed;inset:0;background:rgba(0,0,0,0.4);display:flex;align-items:center;justify-content:center;z-index:9999}.modal-content{background:var(--bg-primary);border-radius:var(--radius-lg);padding:var(--spacing-6);max-width:480px;width:90%;box-shadow:0 20px 60px rgba(0,0,0,0.2)}.modal-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--spacing-5)}.modal-header h3{margin:0;font-size:var(--font-lg)}.modal-close{background:none;border:none;font-size:24px;cursor:pointer;color:var(--text-secondary);padding:0;line-height:1}.modal-close:hover{color:var(--text-primary)}.form-group textarea.form-input{width:100%;padding:var(--spacing-3);border:1px solid var(--border);border-radius:var(--radius-md);font-size:var(--font-base);font-family:inherit;resize:vertical}.form-group select.form-input{width:100%;padding:var(--spacing-3);border:1px solid var(--border);border-radius:var(--radius-md);font-size:var(--font-base);font-family:inherit;background:var(--bg-primary)}.form-actions{display:flex;gap:var(--spacing-3);justify-content:flex-end;margin-top:var(--spacing-5)}.markdown-content{line-height:1.8;color:var(--text-primary);font-size:var(--font-base)}.markdown-content h1{font-size:1.75rem;margin:.5em 0 .5em;font-weight:700}.markdown-content h2{font-size:1.4rem;margin:.4em 0 .4em;font-weight:600}.markdown-content h3{font-size:1.15rem;margin:.3em 0 .3em;font-weight:600}.markdown-content p{margin:.6em 0}.markdown-content strong{font-weight:600}.markdown-content em{font-style:italic}.markdown-content code{background:var(--bg-secondary);padding:2px 6px;border-radius:4px;font-size:.9em}.markdown-content pre{background:var(--bg-secondary);color:var(--text-secondary);padding:16px;border-radius:var(--radius-md);overflow-x:auto;margin:1em 0}.markdown-content pre code{background:none;padding:0;color:inherit}.markdown-content blockquote{border-left:4px solid var(--primary);background:var(--bg-secondary);margin:1em 0;padding:8px 16px;color:var(--text-secondary)}.markdown-content ul,.markdown-content ol{padding-left:2em;margin:.6em 0}.markdown-content ul{list-style-type:disc}.markdown-content ul ul{list-style-type:circle}.markdown-content ul ul ul{list-style-type:square}.markdown-content ol{list-style-type:decimal}.markdown-content ol ol{list-style-type:lower-alpha}.markdown-content ol ol ol{list-style-type:lower-roman}.markdown-content li{margin:.3em 0;display:list-item}.markdown-content a{color:var(--primary);text-decoration:underline}.markdown-content a:hover{color:var(--primary-dark)}.markdown-content img{max-width:100%;border-radius:var(--radius-md);margin:.5em 0}.markdown-content hr{border:none;border-top:2px solid var(--border);margin:1.5em 0}.markdown-content table{width:100%;border-collapse:collapse;margin:1em 0;font-size:var(--font-sm)}.markdown-content th,.markdown-content td{padding:8px 12px;border:1px solid var(--border);text-align:left}.markdown-content th{background:var(--bg-secondary);font-weight:600}.markdown-content tr:nth-child(even){background:var(--bg-tertiary)}.book-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}.level-home-desc{color:#64748b;margin-bottom:20px;font-size:14px}.level-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:16px}.level-card{padding:24px;justify-content:center;text-align:center;min-height:100px}.level-card-completed{background:#dcfce7}.level-card-current{background:#fef3c7}.level-card-locked{background:#f1f5f9;cursor:not-allowed;opacity:.5}.level-number{font-weight:700;font-size:18px}.level-number-completed{color:#166534}.level-number-current{color:#92400e}.level-number-locked{color:#94a3b8}.level-icon{font-size:14px}@media(max-width:1024px){.level-grid{grid-template-columns:repeat(3,1fr)}.book-grid{grid-template-columns:repeat(3,1fr)}}@media(max-width:640px){.level-grid{grid-template-columns:repeat(2,1fr)}.book-grid{grid-template-columns:repeat(2,1fr)}}.auth-section a:hover{text-decoration:none}.practice-board-container{border-radius:var(--radius-lg)!important;background:#f2b06d;box-shadow:0 0 30px rgba(0,0,0,0.5);overflow:hidden;display:flex;justify-content:center;align-items:center;position:relative;z-index:1}.practice-nav-buttons{display:flex;gap:var(--spacing-3);margin-top:var(--spacing-3);justify-content:center}.practice-legend{margin-top:var(--spacing-3);font-size:var(--font-sm);color:var(--text-secondary);text-align:center}.timer-wrapper{position:relative;width:100px;height:100px}.timer-svg{transform:rotate(-90deg)}.board-overlay{position:absolute;top:0;left:0;width:100%;height:100%;display:none;align-items:center;justify-content:center;pointer-events:none;z-index:10000}.board-overlay .overlay-content{padding:var(--spacing-3) var(--spacing-7);border-radius:var(--radius-lg);font-size:var(--font-xl);color:white;text-align:center;display:flex;align-items:center;gap:var(--spacing-2);box-shadow:0 4px 20px rgba(0,0,0,0.4)}.board-overlay .overlay-icon{font-size:24px}.practice-board-container{border-radius:12px!important}.practice-board-wrapper{background:#f2b06d;box-shadow:0 0 30px rgba(0,0,0,0.5);border-radius:8px;overflow:hidden;display:flex;justify-content:center;align-items:center;position:relative;z-index:1}.practice-header{width:100%;display:flex;justify-content:center;align-items:center;margin-bottom:20px;gap:16px}.practice-header h2{margin:0}.practice-status{margin-top:16px;font-size:16px;text-align:center;color:#ffad44;min-height:28px}.practice-nav-buttons{display:flex;gap:12px;margin-top:12px;justify-content:center}.practice-legend{margin-top:12px;font-size:14px;color:#64748b;text-align:center}.legend-correct{color:#2563eb}.legend-wrong{color:#dc2626;margin-left:20px}.timer-wrapper{position:relative;width:100px;height:100px}.timer-svg{transform:rotate(-90deg)}.timer-text{position:absolute;top:0;left:0;width:100%;height:100%;display:flex;align-items:center;justify-content:center;font-size:24px;font-weight:bold;color:#d97706}.timer-center{display:flex;justify-content:center;margin-top:16px}.mode-buttons{display:flex;flex-direction:column;gap:8px;margin-top:12px}.mode-buttons .btn{width:100%}.level-header{width:100%;display:flex;justify-content:center;align-items:center;margin-bottom:20px}.level-header h2{margin:0}.level-loading{width:100%}.level-problem-area{width:100%}.level-progress-container{width:100%;margin-top:16px}.level-progress-text{margin-top:4px;text-align:center}.level-progress-container{width:100%;margin-bottom:20px}.level-progress-container .level-header{width:100%;display:flex;justify-content:space-between;align-items:center;margin-bottom:12px}.level-title{font-size:18px;font-weight:600}.level-problem-number{font-size:14px;color:#64748b}.progress-bar-container{width:100%;height:32px;background-color:#e2e8f0;border-radius:8px;overflow:hidden;position:relative}.progress-bar{height:100%;background-color:#2563eb;display:flex;align-items:center;justify-content:center;transition:width .3s ease}.progress-text{color:white;font-weight:600;font-size:14px}.level-nav-buttons{display:flex;gap:12px;margin-top:20px;justify-content:center}.level-nav-buttons a.btn{text-decoration:none}.level-answer-feedback{width:100%;text-align:center;margin-top:16px}.level-restart-area{width:100%;text-align:center;margin-top:16px}.btn-lg{padding:10px 24px;font-size:15px}.restart-hint{font-size:12px;margin-top:4px}.level-locked{padding:24px}.failure-box{border:2px solid var(--danger);background:var(--danger-light);text-align:center;padding:24px 20px;display:flex;flex-direction:column;align-items:center;gap:12px}.failure-box h3{color:var(--danger);font-size:18px;margin:0}.failure-box p{color:#991b1b;font-size:14px;line-height:1.5;margin:0}.failure-box .btn-danger{margin-top:4px}.level-locked-text{font-size:18px;margin-bottom:8px}.result-area{text-align:center}.result-card{max-width:500px;margin:0 auto}.result-title{font-size:22px}.result-score{font-size:16px;margin:12px 0;white-space:pre-line}