Can someone help with me test class coverage? iam only getting 63%
Trigger:
trigger OppDemoDate on CSActivity__c (before insert, before update) 
{
   Opportunity opt = new  Opportunity();
   
   opt = [select Id,Demo_Date__c from Opportunity where id =:trigger.new[0].OpportunityName__c];
     
    list<CSActivity__c> cslist = [Select c.Start_Date_Time__c, c.OpportunityName__c, c.Id, c.CreatedDate, c.ActivityType__c From CSActivity__c c where c.OpportunityName__c =: opt.id and c.ActivityType__c=:'Demo'  order by c.CreatedDate limit 1];
            
      if(cslist.size()>0)
         {
          if(trigger.new[0].Id == cslist[0].Id){
          opt.Demo_Date__c = trigger.new[0].Start_Date_Time__c;
          update opt;  
          }
         }
         else{
          if(trigger.new[0].ActivityType__c == 'Demo'){
          opt.Demo_Date__c = trigger.new[0].Start_Date_Time__c;
           if(!Test.isRunningTest()){
           update opt;  
          }
          }
        }
 }

Test Class:
@isTest
private class OppDemoDate_test {

    static testMethod void myUnitTest() {
        // TO DO: implement unit test
    
        
      Account acc = new Account(Name = 'test', phone = '1234567890');
      insert acc;
      
      Opportunity opp = new Opportunity(SaleType__c = 'new', Name = 'test', AccountId = acc.Id , 
        Amount = 50, CurrencyIsoCode = 'USD', CloseDate = Date.newInstance(2009,02,01), StageName = 'Closed',
        ForecastCategoryName = 'omitted', Probability_SonoWin__c = '10', Probability_Any_Order__c = '20', SystemType__c = 'Other',
        SystemQty__c = 0, Demo_Date__c = Date.newInstance(2019,02,01) );
      insert opp;
      
      CSActivity__c ccr = new CSActivity__c(Name = 'Test', ActivityType__c = 'Demo', Clinical_Support_Type__c = 'Test', Start_Date_Time__c = Date.newInstance(2009,02,01), Start_Time__c = '0', End_Time__c = '1', Sales_Region__c = 'Test', OpportunityName__c = opp.Id);
      insert ccr;

    }
}