/* don't change anything above line 46 */

* {
   box-sizing: border-box;
}

img {
   /*width: 100%;*/
   display: block;
}

body {
   background-color: #333;
   font-family: 'Lato', sans-serif;
}

.header {
   text-align: center;
   color: white;
   margin: 10vh;
}

.content {  
   max-width: 640px;
   margin: 10vh auto;
   padding: 20px;   
   background-color: white;
   color: black;
   border-radius: 5px;
   font-size: 1em;
   line-height: 1.5em;
   text-align: justify;
}

.content h2 {
   text-align: center;
}

.firebrick {
   color: firebrick;
   background-color: yellow;
}

.pic img {
   width: 100%;   
   border: 2px solid #333;    
   border-radius: 5px; 
}

/* don't change anything above this line */

/* problem one desktop */

.one {
   overflow: hidden;
}

.one .pic {
   float: left;
   width: 50%;
   margin-right: 20px;
}

/* problem two desktop */

.two .picbox {
   display: grid;
   grid-template-columns: 1fr 1fr 1fr 1fr;
   grid-gap: 10px;  
}

/* problem three desktop */

.three .bigphoto {
   width: 100%;   
   border: 2px solid #333;    
   border-radius: 5px;
   margin: auto;
   margin-bottom: 2%;
   cursor: pointer;
   position: relative;
}

.three .bigphoto img {
   width: 100%;   
   border-radius: 3px;
}

.caption {
   position: absolute;
   bottom: 0;
   left: 0;
   width: 100%;
   background-color: rgba(0,0,0,0.8);
   padding: 1% 3%;
   color: linen;
   font-size: 0.8em;
   text-align: right;
   display: none;
}




/* media query for responsive design */

@media only screen and (max-width: 640px) {

   /* header & content mobile */

   .header, .content {
      font-size: 1.5em;
   }

   /* problem one mobile */

   .one .pic {
      width: 100%;
      margin: 10px 0px;
   }

   /* problem two mobile */

   .two .picbox {
      grid-template-columns: 1fr 1fr;
   }

   /* problem three mobile */

   /* nothing required here */

}