To separate styles that apply to layout from those that apply to modules, you should consider the ITCSS (Inverted Triangle CSS) methodology. ITCSS offers a scalable and logical structure for your stylesheets, with layers that guide you in distinguishing between core layout styles and module-specific styles, promoting maintainability and organization.

The "overflow" property in CSS is used to specify how overflows should be handled when content overflows its block container. It can take values like "visible," "hidden," "scroll," and "auto" to control the display of content that overflows its container.

In responsive design, the term "adaptive" describes a layout that adjusts and looks good on all screen sizes and devices. An adaptive design ensures that the content and layout respond effectively to various screen sizes, providing a seamless user experience.

To create a spinner loader animation that rotates 360 degrees indefinitely, you would define it using the @keyframes rule. The correct definition uses Option 2: @keyframes rotate { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }. This specifies a continuous rotation animation starting from 0 degrees and ending at 360 degrees, creating an infinite spinning effect.

To achieve this layout, you should apply grid-row: span 2 to the middle image. This CSS rule will make the middle image span two rows, making it twice as large as the other images in the row.

The @import directive in SCSS is used to import external CSS files into your SCSS code. It's a way to modularize your styles and manage them in separate files, promoting better organization and maintainability.

To set a global color scheme for a website using CSS variables, it's best to define these custom properties in an external CSS file. This allows you to centralize your variable definitions, making it easier to maintain and update the color scheme across your entire website. While you can define CSS variables in other places like the HTML section or inline CSS for specific elements, it's not as efficient or maintainable for global color schemes.

The animation-delay property is used to control the time between the end of one animation iteration and the start of the next. It specifies a delay before the animation begins and can be helpful for creating timed animations and controlling their sequence.

To align all items both vertically and horizontally in a Flexbox container, you can use justify-content: center to center items horizontally and align-items: center to center them vertically. This combination ensures that items are centered in the container along both axes.

The "text-indent" property in CSS is used to adjust the indentation of the first line of a block of text. It specifies the amount by which the first line of a block-level element should be indented from the left margin.