How can I make my CSS look like this $?$

body $\{$

font$-$family: Arial, sans$-$serif;

$\}$

h$1,$ h$2\{$

color: #$333$;

$\}$

ul $\{$

list$-$style$-$type: none;

padding: $0$;

$\}$

li $\{$

padding: $8$px;

background: #f$9$f$9$f$9$;

margin$-$bottom: $5$px;

cursor: pointer;

$\}$

li:hover $\{$

background: #ececec;

$\}$

button $\{$

margin$-$top: $10$px;

padding: $10$px $20$px;

background: #$007$BFF;

color: white;

border: none;

cursor: pointer;

$\}$

button:hover $\{$

background: #$0056$b$3$;

$\}$