chore(docs): update learn intro and caption styles (#566)

Updates learn intro section to discuss background and introduce Omni,
and styles figure captions

task: https://app.asana.com/0/0/1206696792863453/f

docs/site/docs/learn/background/fragmentation.md

@@ -27,6 +27,6 @@ The Omni protocol aims to address these fragmentation challenges by enabling sea
 
 The vision for the future is an interconnected blockchain landscape where fragmentation is a thing of the past. Rollups will continue to play a critical role in scaling, and protocols like Omni are key to ensuring that the ecosystem remains unified and user-friendly.
 
-For more information on how Omni tackles fragmentation and promotes a cohesive blockchain environment read further on [Omni's vision](../introduction/vision.md) and [EigenLayer's enhancing of security through restaking](https://eigenlayer.com/).
+For more information on how Omni tackles fragmentation and promotes a cohesive blockchain environment read further on [Omni and its background](../introduction/introduction.md) and [EigenLayer's enhancing of security through restaking](https://eigenlayer.com/).
 
 Omni is dedicated to bridging the gaps between isolated rollups, fostering a more connected and powerful blockchain infrastructure. Through its innovative protocols, Omni is paving the way for a future where the full potential of blockchain can be realized without the barriers of fragmentation.

docs/site/docs/learn/introduction/introduction.md

@@ -2,10 +2,26 @@
 sidebar_position: 1
 ---
 
-# About
+# Background
 
-Omni is a high performance, high security interoperability network built to aggregate users, liquidity and activity from all rollups, providing developers with the best platform to build cross-rollup applications.
+Ethereum’s commitment to the rollup-centric roadmap has forced the network to scale via isolated execution environments. While this allows rollups to support various execution environments and programming languages, creates negative externalities that degrade Ethereum’s network effects. Specifically, liquidity, users, and developers are fragmented between disparate ecosystems. The expanding variety of rollup designs and their growing adoption will only exacerbate these issues. Consequently, Ethereum requires a native interoperability protocol that realigns the network with its original vision of being a single, unified operating system for decentralized applications.
 
-Omni is the future of interoperability for the Ethereum ecosystem that allows developers to build applications that are available across all rollups without fragmenting their liquidity.
+### The Ideal Interoperability Solution
 
-Omni abstracts away the complexity of building cross-rollup applications by establishing a global storage layer to manage cross-domain applications, accessing liquidity and users across every ecosystem.Developers can work in a familiar environment – the EVM – and don't need to worry about distributed state management. Instead of fragmenting liquidity, application developers can aggregate it across domains, meeting users where they are and creating a smooth product experience.
+The ideal Ethereum interoperability solution must be **secure**, **performant**, and **globally compatible with the Ethereum ecosystem**. To meet our security standards, the solution should derive its security from the same source as Ethereum rollups: Ethereum L1. To be considered performant, the interoperability protocol must verify and process cross-rollup messages with minimal latency. For the protocol to be globally compatible, it must enable applications to be Turing-complete across all rollup environments, ensuring that applications are not limited by the resource constraints of any single rollup.
+
+### Interoperability Verification Approaches
+
+Existing interoperability protocol designs can be broadly classified according to their verification approach.
+
+<figure>
+  <img src="/img/verification-table.png" alt="Interoperability Verification Approaches" />
+  <figcaption>Interoperability verification approaches</figcaption>
+</figure>
+
+Natively verified systems ensure trustless interoperability but require the underlying network security providers to validate state changes. Since rollups derive security from Ethereum L1, Ethereum L1 is the only natively verified solution for rollup interoperability. However, validating rollup state changes on Ethereum L1 via optimistic or zero-knowledge mechanisms is both costly and time consuming, making Ethereum L1 an unfit interoperability solution for rollups.
+
+Similar to a strictly native approach, other approaches also fail to meet our three criteria of security, performance, and global compatibility. Solutions that rely on local verification provide strong security guarantees and can be applied
+across various rollups, yet their inability to handle arbitrary messages limits their application compatibility. Optimistic approaches, which incorporate a latency period for potential challenges, inherently do not satisfy our performance requirement.
+
+Externally verified systems meet our performance and global compatibility needs but require trust in an external verifier set, compromising security. To enhance security, these systems can implement cryptoeconomic security measures that require verifiers to stake capital that is at risk of being slashed for misconduct. However, existing solutions that use this approach derive their cryptoeconomic security from a native asset rather than Ethereum L1, making them unfit for our security requirements. By devising a method to extend Ethereum L1’s cryptoeconomic security to an external set of verifiers, we can fulfill our security criteria and create a novel interoperability solution that offers all three of our desired properties.

docs/site/docs/learn/introduction/omni.md

@@ -0,0 +1,11 @@
+---
+sidebar_position: 2
+---
+
+# Omni
+
+> Omni is a **natively secured**, **externally verified** interoperability network that establishes a new precedent in **security**, **performance**, and **global compatibility** for the future of Ethereum’s modular ecosystem.
+
+Omni realizes this vision by introducing a novel network architecture tailored for low latency cross-rollup communications and global compatibility with Ethereum’s entire rollup ecosystem, underpinned by the cryptoeconomic security of restaked **\$ETH**. This design achieves sub-second cross-rollup message verification while harnessing Ethereum’s industry leading cryptoeconomic security budget. Furthermore, Omni is intentionally designed to be easily integrated with any rollup architecture and local rollup application, while also providing a programmable state layer for managing application deployments across rollups.
+
+With Omni, Ethereum can once again provide a single, unified operating system for decentralized applications, but this time, at a global scale.

docs/site/docs/learn/introduction/whitepaper.md

@@ -1,5 +1,5 @@
 ---
-sidebar_position: 4
+sidebar_position: 3
 ---
 
 # Whitepaper

docs/site/src/css/custom.css

@@ -156,3 +156,9 @@ svg text {
 .sidebar-title > div:hover {
   background-color: transparent;
 }
+
+figcaption {
+  font-size: 0.8em;
+  font-style: italic;
+  font-family: 'Inter';
+}