.lesson-page{min-height:100vh;padding:20px;position:relative;display:flex;transition:padding-left .3s ease}.lesson-header-bar{position:fixed;top:0;left:0;right:0;height:70px;background:var(--gradient-primary-sidebar);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);box-shadow:0 2px 8px var(--shadow-black-medium-dark);z-index:100;display:flex;align-items:center;padding:0 40px;gap:20px}.lesson-menu-toggle{width:40px!important;height:40px!important;min-width:40px!important;padding:0!important;margin:0!important;font-size:1.1rem!important;border-radius:4px!important;align-items:center!important;justify-content:center!important;flex-shrink:0;box-shadow:0 2px 6px var(--shadow-black-normal)!important;align-self:center!important;vertical-align:middle!important}.lesson-menu-toggle,.lesson-page.menu-open .lesson-menu-toggle{display:flex!important}.lesson-menu-toggle:hover{background:var(--color-primary-dark);transform:scale(1.05);box-shadow:0 6px 16px var(--shadow-primary-hover)}.lesson-sidebar{position:fixed;top:70px;left:0;width:300px;height:calc(100vh - 70px);background:var(--gradient-primary-sidebar);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);box-shadow:2px 0 12px var(--shadow-black-medium-dark);z-index:100;transform:translateX(-100%);transition:transform .3s ease;overflow:hidden;display:flex;flex-direction:column}.lesson-sidebar.open{transform:translateX(0)}.lesson-page.menu-open{padding-left:300px}.lesson-page{padding-top:70px}.lesson-menu-overlay{display:none;position:fixed;top:70px;left:0;right:0;bottom:0;background:var(--color-overlay-light);z-index:99;opacity:0;animation:fadeIn .3s ease forwards}@keyframes fadeIn{to{opacity:1}}@media (min-width:769px){.lesson-menu-overlay{display:none!important}}.lesson-sidebar-header{display:flex;justify-content:space-between;align-items:center;padding:24px 20px;border-bottom:2px solid var(--color-white-overlay-20);flex-shrink:0}@media (min-width:769px){.lesson-sidebar-header{display:none}}.lesson-sidebar-header{gap:12px}.lesson-sidebar-header-logo-container{display:flex;align-items:center;gap:12px;flex:1}.lesson-sidebar-header-logo-link{display:flex;align-items:center}.lesson-logo{width:40px;height:40px;cursor:pointer;-o-object-fit:contain;object-fit:contain;border-radius:50%}.lesson-header-logo-container{display:flex;align-items:center;gap:16px;flex:1}.lesson-header-language-container{display:flex;align-items:center;flex-shrink:0}.lesson-header-logo-link{display:flex;align-items:center}.lesson-header-title{color:#fff;font-size:1.5rem;font-weight:700;margin:0;white-space:nowrap;line-height:1}.lesson-sidebar-footer{flex-shrink:0;padding:20px;border-top:2px solid var(--color-white-overlay-20)}.lesson-sidebar-language-container{margin-bottom:15px;display:flex;justify-content:center}.lesson-sidebar-title{color:#fff;font-size:1.5rem;font-weight:700;margin:0}.lesson-sidebar-close{display:none!important}.lesson-sidebar-menu-toggle{width:40px!important;height:40px!important;min-width:40px!important;padding:0!important;margin:0!important;font-size:1.1rem!important;border-radius:4px!important;display:flex!important;align-items:center!important;justify-content:center!important;flex-shrink:0;box-shadow:0 2px 6px var(--shadow-black-normal)!important;background:var(--color-white-overlay-20)!important;color:#fff!important;border:none!important}.lesson-sidebar-menu-toggle:hover{background:var(--color-white-overlay-30)!important;transform:scale(1.05);box-shadow:0 6px 16px var(--shadow-primary-hover)!important}.lesson-sidebar-content{flex:1;padding:20px;display:flex;flex-direction:column;gap:20px;overflow-y:auto;overflow-x:hidden;min-height:0}.lesson-sidebar-back{padding:12px 20px;background:var(--color-bg-white);border-radius:8px;color:var(--color-primary);text-decoration:none;font-weight:600;transition:all .2s ease;text-align:center;box-shadow:0 2px 4px var(--shadow-black-normal)}.lesson-sidebar-back:hover{background:var(--color-bg-light);transform:translateY(-1px);box-shadow:0 4px 8px var(--shadow-black-medium-dark)}.lesson-sidebar-nav{display:flex;flex-direction:column;gap:10px}.lesson-sidebar-item{padding:14px 20px;background:var(--color-white-overlay-20);border-radius:8px;color:#fff;text-decoration:none;font-weight:500;transition:all .2s ease;text-align:center;border:none;cursor:pointer;font-family:inherit;font-size:inherit;width:100%}.lesson-sidebar-item:hover{background:var(--color-white-overlay-30);transform:translateY(-1px)}.lesson-sidebar-item.active{background:var(--color-bg-white);color:var(--color-primary);box-shadow:0 2px 4px var(--shadow-black-normal);font-weight:600}@media (min-width:769px){.lesson-sidebar-alphabet-btn{display:none}}.lesson-sidebar-navigation{display:flex;gap:10px;margin-top:auto}.lesson-sidebar-nav-btn{flex:1;padding:8px 12px;background:var(--color-bg-white);border-radius:8px;color:var(--color-primary);text-decoration:none;font-weight:600;transition:all .2s ease;text-align:center;font-size:.9rem;box-shadow:0 2px 4px var(--shadow-black-normal);display:flex;align-items:center;justify-content:center}.nav-btn-content{display:flex;flex-direction:row;align-items:center;gap:6px;white-space:nowrap}.nav-btn-arrow{font-size:.9rem;line-height:1}.nav-btn-label{font-size:.85rem;line-height:1;font-weight:500}.nav-btn-number{font-size:1rem;line-height:1;font-weight:700}.lesson-sidebar-nav-btn:hover:not(.disabled){background:var(--color-bg-light);transform:translateY(-1px);box-shadow:0 4px 8px var(--shadow-black-medium-dark)}.lesson-sidebar-nav-btn.disabled{background:var(--color-white-overlay-30);color:var(--color-white-overlay-70);cursor:not-allowed;box-shadow:none}.lesson-sidebar-arrow-btn{width:48px!important;min-width:48px!important;height:48px!important;padding:0!important;display:flex!important;align-items:center!important;justify-content:center!important;font-size:1.2rem!important;flex-shrink:0}.lesson-sidebar-current-lesson-btn{flex:1;padding:12px 16px!important;font-size:.95rem!important;font-weight:800!important;min-height:48px!important;height:48px!important;color:#fff!important;text-shadow:0 2px 4px rgba(0,0,0,.5),0 1px 2px rgba(0,0,0,.7)!important;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}.lesson-container{max-width:1200px;margin:0 auto;width:100%;height:calc(100vh - 70px);transition:width .3s ease,max-width .3s ease}.lesson-header-wrapper{display:none}.lesson-header{display:flex;align-items:center;justify-content:space-between;gap:20px;margin-bottom:20px;position:relative}.back-button{padding:10px 20px;background:var(--color-bg-white);border-radius:8px;color:var(--color-primary);text-decoration:none;font-weight:600;transition:all .2s ease;border:none;flex-shrink:0;box-shadow:0 2px 4px var(--shadow-black-normal)}.back-button:hover{background:var(--color-bg-light);transform:translateY(-1px);box-shadow:0 4px 8px var(--shadow-black-medium-dark)}.lesson-title{color:#fff;font-size:2rem;font-weight:700;margin:0;flex:1;text-align:center;letter-spacing:-.5px}.lesson-navigation{display:flex;gap:10px;flex-shrink:0}.nav-lesson-btn{padding:10px 16px;background:var(--color-bg-white);border-radius:8px;color:var(--color-primary);text-decoration:none;font-weight:600;transition:all .2s ease;border:none;font-size:.9rem;box-shadow:0 2px 4px var(--shadow-black-normal)}.nav-lesson-btn:hover:not(.disabled){background:var(--color-bg-light);transform:translateY(-1px);box-shadow:0 4px 8px var(--shadow-black-medium-dark)}.nav-lesson-btn.disabled{background:var(--color-white-overlay-30);color:var(--color-white-overlay-70);cursor:not-allowed;box-shadow:none}.lesson-nav{display:flex;gap:8px;margin-bottom:0;flex-wrap:wrap;justify-content:center}.nav-item{padding:10px 20px;background:var(--color-white-overlay-20);border-radius:8px;color:#fff;text-decoration:none;font-weight:500;transition:all .2s ease;border:none;font-size:.95rem}.nav-item:hover{background:var(--color-white-overlay-30);transform:translateY(-1px)}.nav-item.active{background:var(--color-bg-white);color:var(--color-primary);box-shadow:0 2px 4px var(--shadow-black-normal)}.lesson-content{background:var(--color-white-overlay-95);border-radius:16px;padding:30px;min-height:500px;box-shadow:0 8px 32px var(--shadow-black-normal)}@media (max-width:768px){.lesson-container{height:calc(100vh - 80px)}.lesson-page{padding:80px 5px 5px}.lesson-header-bar{height:80px;padding:0 20px;gap:16px}.lesson-menu-toggle,.lesson-sidebar-menu-toggle{width:36px!important;height:36px!important;min-width:36px!important;font-size:.95rem!important}.lesson-header-title{font-size:1.25rem}.lesson-logo{width:36px;height:36px}.lesson-sidebar{top:0;height:100vh;z-index:101}.lesson-page.menu-open{padding-left:0}.lesson-page.menu-open .lesson-container{width:100%;max-width:100%}.lesson-page.menu-open .lesson-header-wrapper{display:none}.lesson-menu-toggle{font-size:14px}.lesson-menu-toggle,.lesson-sidebar-menu-toggle{width:44px!important;height:44px!important;min-width:44px!important;padding:0!important;border-radius:4px!important}.lesson-sidebar-menu-toggle{font-size:14px!important}.lesson-sidebar{width:280px}.lesson-menu-overlay{display:none;position:fixed;top:60px;left:0;right:0;bottom:0;background:var(--color-overlay-light);z-index:99;opacity:0;animation:fadeIn .3s ease forwards}@keyframes fadeIn{to{opacity:1}}.lesson-page.menu-open .lesson-menu-overlay{display:block}.lesson-header-wrapper{position:static;margin:0 0 8px;padding:8px}.lesson-header{flex-direction:column;align-items:stretch;gap:6px;margin-bottom:6px}.lesson-title{font-size:1.75rem;text-align:center}.lesson-navigation{justify-content:center;width:100%}.nav-lesson-btn{flex:1;text-align:center;padding:5px 8px;font-size:.85rem}.back-button{padding:5px 10px;font-size:.9rem}.lesson-nav{flex-direction:column;gap:4px}.nav-item{text-align:center;padding:5px 8px}.lesson-content{padding:8px}}