.spinner {
    border: 3px solid #f3f3f3;
    border-top: 3px solid #25D366;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.sidebar { transition: transform 0.3s ease-in-out; }
.sidebar-item { transition: all 0.2s ease; }
.sidebar-item:hover { background-color: rgba(37, 211, 102, 0.1); }
.sidebar-item.active {
    background-color: rgba(37, 211, 102, 0.2);
    border-left: 4px solid #25D366;
}

.section-content { display: none; }
.section-content.active { display: block; }

#loginScreen { background: linear-gradient(135deg, #128C7E 0%, #25D366 100%); }

.session-card { transition: transform 0.2s ease, box-shadow 0.2s ease; }
.session-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

.active-session-badge {
    animation: pulse 2s ease-in-out infinite;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

/* Efecto heartbeat para sesión activa */
.heartbeat-active {
    animation: heartbeat 1.5s ease-in-out infinite;
}

@keyframes heartbeat {
    0% { transform: scale(1); box-shadow: 0 0 0 0 rgba(139, 92, 246, 0.4); }
    25% { transform: scale(1.02); }
    35% { transform: scale(1); }
    45% { transform: scale(1.02); }
    55% { transform: scale(1); box-shadow: 0 0 20px 10px rgba(139, 92, 246, 0); }
    100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(139, 92, 246, 0); }
}

/* Secciones */
.section-content {
    display: none;
}

.section-content.active {
    display: block;
    animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}