Theme update (#553)

* Start to update the theme

- Ligther colors
- No more border radius
- Buttons are now always colored
- Start to redesign the post page (according to the Figma mockups)

* Fix build script: it now recompiles everytime a scss file changed

* Make sure the article illustrations are not too big

* Make articles wider (70 characters)

* Better contrast between gray shades

* Various improvements

* Better mobile style

* New style for the footer

* Improve comment style

* Better responsiveness again

* Limit the size of the article cover

* Last details?

- Improve buttons on the media page
- Improve lists

* Pin the stdweb version that we use

It changed because I removed Cargo.lock to handle a merge conflict

I could have updated cargo web too, but it mean I should have re-built
the CI docker image and it was taking forever.

* Better contrast for links in the header of the article

* Add a basic privacy policy

* Remove "also"

* Fix a few issues

- Don't watch static/css in build.rs
- Another shade of white
- Remove useless margin rule for error messages

build.rs

@@ -41,7 +41,12 @@ fn main() {
     let in_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap()).join("templates");
     compile_templates(&in_dir, &out_dir).expect("compile templates");
 
-    println!("cargo:rerun-if-changed=static/css");
+    println!("cargo:rerun-if-changed=static/css/_article.scss");
+    println!("cargo:rerun-if-changed=static/css/_forms.scss");
+    println!("cargo:rerun-if-changed=static/css/_global.scss");
+    println!("cargo:rerun-if-changed=static/css/_header.scss");
+    println!("cargo:rerun-if-changed=static/css/_variables.scss");
+    println!("cargo:rerun-if-changed=static/css/main.scss");
     let mut out = File::create("static/css/main.css").expect("Couldn't create main.css");
     out.write_all(
         &rsass::compile_scss_file(