:root{--primary-color:#4a6fa5;--primary-dark:#2a4a7f;--primary-light:#3a5a8f;--success-color:#28a745;--danger-color:#dc3545;--warning-color:#ffc107;--info-color:#17a2b8;--light-gray:#f5f5f5;--dark-gray:#333;--bg-color:#000;--text-color:white;--card-bg:white;--card-text:#333}[data-theme=light]{--bg-color:#ffffff;--text-color:#333;--card-bg:#f8f9fa;--card-text:#333}[data-theme=dark]{--bg-color:#000;--text-color:white;--card-bg:#2d2d2d;--card-text:white}*{margin:0;padding:0;box-sizing:border-box;font-family:'Segoe UI',Tahoma,Geneva,Verdana,sans-serif}body{background:var(--bg-color);padding:0!important;color:var(--text-color);transition:background-color .3s ease,color .3s ease}.container{max-width:1600px;margin:80px auto 20px;background:var(--card-bg);color:var(--card-text);border-radius:20px;box-shadow:0 0 20px rgba(0,0,0,.3);overflow:hidden;height:calc(100vh - 100px);display:flex;flex-direction:column;transition:background-color .3s ease,color .3s ease}.header-logo{text-align:center;padding:15px;border-bottom:2px solid #f0f0f0}.header-logo img{max-height:60px;max-width:100%}.navigation-header{position:fixed;top:0;left:0;right:0;background:linear-gradient(135deg,#000);color:#fff;display:flex;justify-content:space-between;align-items:center;z-index:1000;box-shadow:0 2px 10px rgba(0,0,0,.1);transition:background-color .3s ease,color .3s ease}[data-theme=light] .navigation-header{background:linear-gradient(135deg,#fff,#f8f9fa);color:#333;box-shadow:0 2px 10px rgba(0,0,0,.1)}[data-theme=dark] .navigation-header{background:linear-gradient(135deg,#2d2d2d,#1a1a1a);color:#fff;box-shadow:0 2px 10px rgba(0,0,0,.3)}.nav-left{display:flex;align-items:center;gap:15px}.nav-right{display:flex;gap:10px}.nav-buttons{display:flex;gap:10px}.nav-buttons button{padding:8px 15px;background-color:var(--primary-color);color:#fff;border:none;border-radius:4px;cursor:pointer;font-weight:600;transition:all .2s ease;display:flex;align-items:center;gap:5px;text-decoration:none}.nav-buttons button:hover{transform:translateY(-1px);background-color:var(--primary-dark)}.nav-buttons button.logout{background-color:var(--danger-color)}.nav-buttons button.logout:hover{background-color:#c82333}.chat-container{display:flex;height:100%;flex:1}.sidebar{width:350px;background:#f8f9fa;border-right:2px solid #e9ecef;display:flex;flex-direction:column}.sidebar-header{padding:20px;background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff;text-align:center}.sidebar-header h3{margin-bottom:10px}.user-role-badge{padding:4px 12px;background:rgba(255,255,255,.2);border-radius:15px;font-size:.9rem;text-transform:capitalize}.groups-list{flex:1;overflow-y:auto;padding:15px}.group-item{background:#fff;border:2px solid #e9ecef;border-radius:10px;padding:15px;margin-bottom:10px;cursor:pointer;transition:all .3s ease;position:relative}.group-item:hover{border-color:var(--primary-color);transform:translateY(-2px)}.group-item.active{border-color:var(--primary-color);background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff}.group-item.auto-joined{border-color:var(--success-color);background:linear-gradient(135deg,var(--success-color),#1e7e34);color:#fff}.group-name{font-weight:600;font-size:1.1rem;margin-bottom:5px}.group-code{font-size:.9rem;opacity:.8;margin-bottom:8px}.group-members{font-size:.8rem;opacity:.7}.unread-badge{position:absolute;top:10px;right:10px;background:var(--danger-color);color:#fff;border-radius:50%;width:20px;height:20px;display:flex;align-items:center;justify-content:center;font-size:.7rem;font-weight:700}.auto-badge{position:absolute;top:10px;right:10px;background:var(--success-color);color:#fff;border-radius:10px;padding:2px 8px;font-size:.7rem;font-weight:700}.chat-area{flex:1;display:flex;flex-direction:column;background:#fff;height:100%;min-height:0;position:relative}.chat-header{padding:20px;background:linear-gradient(135deg,#f8f9fa,#e9ecef);border-bottom:2px solid #dee2e6;display:flex;justify-content:space-between;align-items:center;flex-shrink:0}.chat-title{font-size:1.4rem;font-weight:700;color:var(--primary-color)}.chat-info{font-size:.9rem;color:#666}.online-indicator{display:flex;align-items:center;gap:8px;color:var(--success-color)}.online-dot{width:8px;height:8px;background:var(--success-color);border-radius:50%;animation:pulse 2s infinite}@keyframes pulse{0%{opacity:1}50%{opacity:.5}100%{opacity:1}}.messages-container{flex:1;overflow-y:auto;padding:20px;background:#f8f9fa;padding-bottom:120px;min-height:0;margin-bottom:0}.message{margin-bottom:15px;max-width:70%;animation:fadeInUp .3s ease-out}.message.own{margin-left:auto}.message-header{display:flex;align-items:center;gap:10px;margin-bottom:5px}.message.own .message-header{justify-content:flex-end}.message-avatar{width:32px;height:32px;background:var(--primary-color);border-radius:50%;display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;font-size:.9rem;object-fit:cover}.message-avatar img{width:100%;height:100%;border-radius:50%;object-fit:cover}.message-info{display:flex;flex-direction:column;gap:2px}.message.own .message-info{align-items:flex-end}.message-sender{font-weight:600;color:var(--primary-color);font-size:.9rem}.message-time{font-size:.7rem;color:#666}.message-content{background:#fff;padding:12px 16px;border-radius:18px;border:1px solid #e9ecef;word-wrap:break-word;box-shadow:0 2px 4px rgba(0,0,0,.05);position:relative}.message.own .message-content{background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff;border:none}.message-actions{position:absolute;top:-8px;right:-8px;opacity:0;transition:opacity .2s ease}.message:hover .message-actions{opacity:1}.delete-message-btn{background:var(--danger-color);color:#fff;border:none;border-radius:50%;width:24px;height:24px;display:flex;align-items:center;justify-content:center;cursor:pointer;font-size:.7rem;box-shadow:0 2px 4px rgba(0,0,0,.2);transition:all .2s ease}.delete-message-btn:hover{background:#c82333;transform:scale(1.1)}.message-input-area{padding:20px;background:#fff;border-top:2px solid #e9ecef;position:sticky;bottom:0;left:0;right:0;z-index:100;min-height:85px;max-height:200px;box-shadow:0 -2px 10px rgba(0,0,0,.1)}.message-input-container{display:flex;gap:10px;align-items:flex-end}.message-input{flex:1;border:2px solid #e9ecef;border-radius:25px;padding:12px 20px;font-size:1rem;resize:none;max-height:120px;min-height:45px}.message-input:focus{outline:0;border-color:var(--primary-color);box-shadow:0 0 0 3px rgba(74,111,165,.1)}.send-button{width:45px;height:45px;background:var(--primary-color);color:#fff;border:none;border-radius:50%;cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:1.1rem;transition:all .3s ease}.send-button:hover{background:var(--primary-dark);transform:scale(1.05)}.send-button:disabled{background:#ccc;cursor:not-allowed;transform:none}.empty-chat{display:flex;flex-direction:column;align-items:center;justify-content:center;height:100%;color:#666;text-align:center;padding:40px}.empty-chat i{font-size:4rem;margin-bottom:20px;color:#ddd}.empty-chat h3{margin-bottom:10px;color:var(--dark-gray)}.loading-messages{display:flex;align-items:center;justify-content:center;padding:40px;color:#666}.loading-messages i{margin-right:10px;animation:spin 1s linear infinite}.mobile-nav-toggle{display:none;background:0 0;border:none;color:var(--primary-color);font-size:24px;cursor:pointer;padding:8px;border-radius:4px;transition:background-color .3s,color .3s}.mobile-nav-toggle:hover{background-color:var(--primary-color);color:#fff}.mobile-nav-menu{display:none;position:fixed;top:60px;right:20px;background:#fff;border-radius:8px;box-shadow:0 8px 25px rgba(0,0,0,.15);min-width:220px;overflow:hidden;z-index:1001;animation:slideDown .3s ease-out;border:1px solid var(--primary-color)}@keyframes slideDown{from{opacity:0;transform:translateY(-10px)}to{opacity:1;transform:translateY(0)}}.mobile-nav-menu.show{display:block}.mobile-nav-menu button{width:100%;padding:15px 20px;text-align:left;background:0 0;border:none;color:#333;font-size:16px;font-weight:500;border-bottom:1px solid #f0f0f0;transition:all .3s;display:flex;align-items:center;gap:12px}.mobile-nav-menu button:last-child{border-bottom:none}.mobile-nav-menu button:hover{background-color:var(--primary-color);color:#fff}.mobile-nav-menu button.logout{color:#dc3545}.mobile-nav-menu button.logout:hover{background-color:#dc3545;color:#fff}@media (max-width:768px){body{background-color:#fff}.container{margin:10px;border-radius:10px;height:calc(100vh - 30px)}.navigation-header{background:#fff}.nav-buttons{display:none!important}.mobile-nav-toggle{display:block!important}.chat-container{flex-direction:column}.sidebar{width:100%;height:40%;border-right:none;border-bottom:2px solid #e9ecef}.chat-area{height:60%}.message{max-width:85%}.header-logo{padding:10px}.header-logo img{max-height:40px}.messages-container{padding-bottom:140px!important}.message-input-area{min-height:90px;padding:15px}}@keyframes fadeInUp{from{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}@keyframes spin{0%{transform:rotate(0)}100%{transform:rotate(360deg)}}.groups-list::-webkit-scrollbar,.messages-container::-webkit-scrollbar{width:6px}.groups-list::-webkit-scrollbar-track,.messages-container::-webkit-scrollbar-track{background:#f1f1f1;border-radius:3px}.groups-list::-webkit-scrollbar-thumb,.messages-container::-webkit-scrollbar-thumb{background:var(--primary-color);border-radius:3px}.groups-list::-webkit-scrollbar-thumb:hover,.messages-container::-webkit-scrollbar-thumb:hover{background:var(--primary-dark)}