"Design a modern and visually appealing application for learning English vocabulary, specifically tailored for Russian-speaking users. The application should feature a sleek, user-friendly interface, utilizing digital flashcards as the core method for learning and reviewing words. Incorporate the following functionality to enhance user engagement and learning outcomes: 1. Onboarding and Personalization: A welcome screen introducing the app's purpose and features. Personalized learning paths based on the user's level (beginner, intermediate, advanced) and goals (e.g., travel, business English, academic vocabulary). Optional placement test to determine initial proficiency level. 2. Flashcard Learning: Interactive flashcards with English words, their Russian translations, pronunciation guides, and example sentences. Option to listen to native speaker pronunciation for better learning. Images or icons associated with words to aid memory through visual association. 3. Progress Tracking: Daily, weekly, and monthly learning goals. Visual progress charts showing mastered words and overall achievements. Streak tracking to motivate consistent learning. 4. Spaced Repetition System (SRS): Intelligent scheduling of flashcard reviews to optimize retention using SRS algorithms. Notifications for daily practice and review sessions. 5. Interactive Quizzes and Games: Multiple-choice quizzes, word scrambles, and matching games for engaging practice. Timed challenges to test speed and recall. 6. Custom Vocabulary Lists: Pre-built word lists by theme (e.g., travel, food, technology). Ability for users to create and save their own vocabulary sets. 7. Social and Competitive Features: Leaderboards for friendly competition. Options to share progress and achievements with friends. Community forums or chat groups for peer interaction. 8. Offline Mode: Access to downloaded vocabulary sets and progress tracking without an internet connection. 9. Premium Features (Optional): Advanced learning statistics. Access to premium vocabulary packs or additional features like grammar lessons and video explanations. 10. Accessibility: Support for dark mode for comfortable night-time use. Voice input for hands-free learning. Adjustable font sizes and text-to-speech support for users with visual impairments. Ensure the app has a modern aesthetic with clean typography, intuitive navigation, and a playful yet professional color palette. Use animations and transitions sparingly to maintain focus on learning while keeping the experience smooth and enjoyable."