What justify-content value do these div elements have?

<html> <head> <style> .container { display: flex; width: auto; flex-direction: column; justify-content: center; width: 200px; height: 500px; /* background:linear-gradient(to right, #77A1D3 0%, #79CBCA 51%, #77A1D3 100%); */ border-radius: 10px; border: 2px solid gray; } body { background: white;} .container-image { display: flex; width: auto; flex-direction: row; justify-content: center; width: 100%; margin-bottom: 30px; } .item { background-color: lightgray; font-weight: bold; margin: 10px; padding: 5px; text-align: center; border-radius: 10px; border: 3px solid lightgray; } img { border-radius: 10px; } h2 {  } </style> </head> <body> <h2>"Science" Column</h2> <div class="container"> <div class="item">Venus upset over Pluto being declassified as a planet. </div> <div class="item">The verdict is in: dogs are only man's second best friend. </div> </div> </body> </html> ]]>centerspace-around

Make sure to pick center.