Adjust square size and default sliders values

The window was too big in smaller resolutions (and it currently
can't be resized), now it should fit at least 768px height
screens.
Both rating sliders were starting at 50, now they have sane
initial values (min 0 - max 1000)

src/main.rs

@@ -10,7 +10,7 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-const SQUARE_SIZE: u16 = 68;
+const SQUARE_SIZE: u16 = 60;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct PositionGUI {
@@ -408,10 +408,10 @@ impl Default for OfflinePuzzles {
             theme : TaticsThemes::default(),
 
             slider_min_rating_state: slider::State::new(),
-            slider_min_rating_value: 50,
+            slider_min_rating_value: 0,
 
             slider_max_rating_state: slider::State::new(),
-            slider_max_rating_value: 50,
+            slider_max_rating_value: 1000,
 
             btn_search_state: button::State::new(),