Which of the following is a valid CSS rule?
h1 {
color: blue;
}
style="color:blue;"
css="color:blue;"
h1 {
color {
blue;
}
}
h1 {
color: blue;
}
h1 {
color: blue;
}
style="color:blue;"
css="color:blue;"
h1 {
color {
blue;
}
}
color: blue;
}