protected function getScssVars() {

		$sass = '';

		// Required
		foreach ( $this->requiredSassVars as $var ) {
			$method = $this->varToGetter( $var );

			if ( ! method_exists( $this->input, $method ) ) {
				throw new \LogicException( "Input::{$method}() not found." );
			}
			if ( empty( $this->input->{$method}() ) ) {
				throw new \InvalidArgumentException( "Input::{$method}() cannot be empty." );
			}

			$sass .= "\${$var}: " . $this->input->{$method}() . ";\n";
		}

		// Optional
		foreach ( $this->optionalSassVars as $var ) {
			$method = $this->varToGetter( $var );

			if ( method_exists( $this->input, $method ) && ! empty( $this->input->{$method}() ) ) {
				$sass .= "\${$var}: " . $this->input->{$method}() . ";\n";
			}
		}

		return $sass;
	}