Chore: Desktop: Fix SCSS compilation warning

[personalizedrefrigerator]

Summary

This pull request fixes the following warning, which was previously printed when running yarn start in packages/app-desktop:

Deprecation Warning: Sass's behavior for declarations that appear after nested
rules will be changing to match the behavior specified by CSS in an upcoming
version. To keep the existing behavior, move the declaration above the nested
rule. To opt into the new behavior, wrap the declaration in `& {}`.

More info: https://sass-lang.com/d/mixed-decls

    ╷
18  │ ┌     &:disabled {
19  │ │         opacity: 0.3;
20  │ │     }
    │ └─── nested rule
... │
22  │       display: flex;
    │       ^^^^^^^^^^^^^ declaration
    ╵
    app-desktop/gui/styles/toolbar-button.scss 22:2  @use
    app-desktop/gui/styles/index.scss 7:1            @use
    app-desktop/style.scss 16:1                      root stylesheet

Show warnings for other lines (same file)

Deprecation Warning: Sass's behavior for declarations that appear after nested
rules will be changing to match the behavior specified by CSS in an upcoming
version. To keep the existing behavior, move the declaration above the nested
rule. To opt into the new behavior, wrap the declaration in `& {}`.

More info: https://sass-lang.com/d/mixed-decls

    ╷
18  │ ┌     &:disabled {
19  │ │         opacity: 0.3;
20  │ │     }
    │ └─── nested rule
... │
23  │       align-items: center;
    │       ^^^^^^^^^^^^^^^^^^^ declaration
    ╵
    app-desktop/gui/styles/toolbar-button.scss 23:2  @use
    app-desktop/gui/styles/index.scss 7:1            @use
    app-desktop/style.scss 16:1                      root stylesheet

Deprecation Warning: Sass's behavior for declarations that appear after nested
rules will be changing to match the behavior specified by CSS in an upcoming
version. To keep the existing behavior, move the declaration above the nested
rule. To opt into the new behavior, wrap the declaration in `& {}`.

More info: https://sass-lang.com/d/mixed-decls

    ╷
18  │ ┌     &:disabled {
19  │ │         opacity: 0.3;
20  │ │     }
    │ └─── nested rule
... │
24  │       justify-content: center;
    │       ^^^^^^^^^^^^^^^^^^^^^^^ declaration
    ╵
    app-desktop/gui/styles/toolbar-button.scss 24:2  @use
    app-desktop/gui/styles/index.scss 7:1            @use
    app-desktop/style.scss 16:1                      root stylesheet

Deprecation Warning: Sass's behavior for declarations that appear after nested
rules will be changing to match the behavior specified by CSS in an upcoming
version. To keep the existing behavior, move the declaration above the nested
rule. To opt into the new behavior, wrap the declaration in `& {}`.

More info: https://sass-lang.com/d/mixed-decls

    ╷
18  │ ┌     &:disabled {
19  │ │         opacity: 0.3;
20  │ │     }
    │ └─── nested rule
... │
25  │       cursor: default;
    │       ^^^^^^^^^^^^^^^ declaration
    ╵
    app-desktop/gui/styles/toolbar-button.scss 25:2  @use
    app-desktop/gui/styles/index.scss 7:1            @use
    app-desktop/style.scss 16:1                      root stylesheet

Deprecation Warning: Sass's behavior for declarations that appear after nested
rules will be changing to match the behavior specified by CSS in an upcoming
version. To keep the existing behavior, move the declaration above the nested
rule. To opt into the new behavior, wrap the declaration in `& {}`.

More info: https://sass-lang.com/d/mixed-decls

    ╷
18  │ ┌     &:disabled {
19  │ │         opacity: 0.3;
20  │ │     }
    │ └─── nested rule
... │
26  │       border-radius: 3px;
    │       ^^^^^^^^^^^^^^^^^^ declaration
    ╵
    app-desktop/gui/styles/toolbar-button.scss 26:2  @use
    app-desktop/gui/styles/index.scss 7:1            @use
    app-desktop/style.scss 16:1                      root stylesheet

Warning: 8 repetitive deprecation warnings omitted.

Screenshot comparison

Before	After