1-1/2 cups graham cracker crumbs (about 24 squares)
1/3 cup plus 1/4 cup sugar, divided
1/2 cup butter, melted
1 package (3 ounces) strawberry gelatin
3 cups boiling water, divided
1-1/4 cups cold water, divided
1 package (3 ounces) lime gelatin
1 package (3 ounces) lemon gelatin
1 can (8 ounces) crushed pineapple, drained
3 tablespoons lemon juice
1-1/2 cups heavy whipping cream, whipped
1/4 cup chopped walnuts
In a bowl, combine the cracker crumbs, 1/3 cup sugar and butter; press onto the bottom and 2 in. up the sides of a greased 9-in. springform pan. Refrigerate.
In a small bowl, dissolve strawberry gelatin in 1 cup boiling water; stir in 1/2 cup cold water. Pour into an 8-in. square dish coated with cooking spray; chill until firm. Repeat with lime gelatin, pouring into another 8-in. square dish.
In a large bowl, dissolve lemon gelatin and remaining sugar in remaining boiling water. Add pineapple, lemon juice, salt and remaining cold water. Refrigerate until partially set, about 1 hour. Beat on medium speed until foamy, about 2 minutes.
Cut strawberry and lime gelatin into 1/2-in. cubes; set aside 1/4 cup of each for garnish. Fold remaining cubes into lemon gelatin. Fold in whipped cream. Spoon into crust. Top with walnuts and reserved gelatin cubes. Cover and refrigerate for at least 6 hours. Remove sides of pan. Cut into wedges.