Change font size and color in slider title - subtitle

I have made a simple sydney pro website in clinconf2016.gr (Greek)
and i want to change the font size and Color in first slide for
title and subtitle.

What is the css code to i need to use in order to achive that?

I also wanted the same changes for navigation menu.
Will be done through css?

Finaly i attach my current custom css code bellow.

================================================
/* Enter Your Custom CSS Here /
.site-title,
.site-description {
text-shadow: 2px 2px 2px #000;
}
/
Enter Your Custom CSS Here */
.site-title,
.site-description {
text-shadow: 2px 2px 2px #000;
}
.btn-menu {
text-shadow: 2px 2px 2px #000;
}

.text-slider .subtitle {
font-size: 16px;
}

@media only screen and (max-width: 767px){
h1.site-title {
font-size: 20px !important;
}

h2.site-description {
font-size: 14px !important;
}

.text-slider-section {
top: 70%;
}

.header-image {
height: 290px;
}

.page-wrap {
padding-top: 15px;
}
}
@media only screen and (max-width: 1024px){
h2.site-description, .text-slider .subtitle {
font-size: 18px;
}

.text-slider-section {
top: 70%;
}

.header-image {
height: 260px;
}

.page-wrap {
padding-top: 15px;
}
}

I found out that the
.text-slider .subtitle {
is the attritube for subtitle changes but for the rest?
title, navigation menu?

Hi,

For the title the selector is .text-slider .maintitle and for the nav it’s #mainnav ul li a