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Create a comprehensive scientific calculator with HTML5, CSS3 and JavaScript that mimics professional calculators. Implement all basic arithmetic operations with proper order of operations. Include advanced scientific functions (trigonometric, logarithmic, exponential, statistical) with degree/radian toggle. Add memory operations (M+, M-, MR, MC) with visual indicators. Maintain a scrollable calculation history log that can be cleared or saved. Implement full keyboard support with appropriate key mappings and shortcuts. Add robust error handling for division by zero, invalid operations, and overflow conditions with helpful error messages. Create a responsive design that transforms between standard and scientific layouts based on screen size or orientation. Include multiple theme options (classic, modern, high contrast). Add optional sound feedback for button presses with volume control. Implement copy/paste functionality for results and expressions.

Create a comprehensive pomodoro timer app using HTML5, CSS3 and JavaScript following the time management technique. Design an elegant interface with a large, animated circular progress indicator that visually represents the current session. Allow customization of work intervals (default ${Work Intervals:25min}), short breaks (default ${Short Breaks:5min}), and long breaks (default ${Long Breaks:15min}). Include a task list integration where users can associate pomodoro sessions with specific tasks. Add configurable sound notifications for interval transitions with volume control. Implement detailed statistics tracking daily/weekly productivity with visual charts. Use localStorage to persist settings and history between sessions. Make the app installable as a PWA with offline support and notifications. Add keyboard shortcuts for quick timer control (start/pause/reset). Include multiple theme options with customizable colors and fonts. Add a focus mode that blocks distractions during work intervals.

Develop a comprehensive interactive quiz application with HTML5, CSS3 and JavaScript. Create an engaging UI with smooth transitions between questions. Support multiple question types including multiple choice, true/false, matching, and short answer with automatic grading. Implement configurable timers per question with visual countdown. Add detailed score tracking with points based on difficulty and response time. Show a dynamic progress bar indicating completion percentage. Include a review mode to see correct/incorrect answers with explanations after quiz completion. Implement a persistent leaderboard using localStorage. Organize questions into categories with custom icons and descriptions. Support multiple difficulty levels affecting scoring and time limits. Generate a detailed results summary with performance analytics and improvement suggestions. Add social sharing functionality for results with customizable messages.

Build a professional-grade color tool with HTML5, CSS3 and JavaScript for designers and developers. Create an intuitive interface with multiple selection methods including eyedropper, color wheel, sliders, and input fields. Implement real-time conversion between color formats (RGB, RGBA, HSL, HSLA, HEX, CMYK) with copy functionality. Add a color palette generator with options for complementary, analogous, triadic, tetradic, and monochromatic schemes. Include a favorites system with named collections and export options. Implement color harmony rules visualization with interactive adjustment. Create a gradient generator supporting linear, radial, and conic gradients with multiple color stops. Add an accessibility checker for WCAG compliance with contrast ratios and colorblindness simulation. Implement one-click copy for CSS, SCSS, and SVG code snippets. Include a color naming algorithm to suggest names for selected colors. Support exporting palettes to various formats (Adobe ASE, JSON, CSS variables, SCSS).

Create a comprehensive secure password generator using HTML5, CSS3 and JavaScript with cryptographically strong randomness. Build an intuitive interface with real-time password preview. Allow customization of password length with presets for different security levels. Include toggles for character types (uppercase, lowercase, numbers, symbols) with visual indicators. Implement an advanced strength meter showing entropy bits and estimated crack time. Add a one-click copy button with confirmation and automatic clipboard clearing. Create a password vault feature with encrypted localStorage storage. Generate multiple passwords simultaneously with batch options. Maintain a password history with generation timestamps. Calculate and display entropy using standard formulas. Offer memorable password generation options (phrase-based, pattern-based). Include export functionality with encryption options for password lists.

Build a comprehensive weather dashboard using HTML5, CSS3, JavaScript and the OpenWeatherMap API. Create a visually appealing interface showing current weather conditions with appropriate icons and background changes based on weather/time of day. Display a detailed 5-day forecast with expandable hourly breakdown for each day. Implement location search with autocomplete and history, supporting both city names and coordinates. Add geolocation support to automatically detect user's location. Include toggles for temperature units (°C/°F) and time formats. Display severe weather alerts with priority highlighting. Show detailed meteorological data including wind speed/direction, humidity, pressure, UV index, and air quality when available. Include sunrise/sunset times with visual indicators. Create a fully responsive layout using CSS Grid that adapts to all device sizes with appropriate information density.

Develop a comprehensive currency converter using HTML5, CSS3, JavaScript and a reliable Exchange Rate API. Create a clean, intuitive interface with prominent input fields and currency selectors. Implement real-time exchange rates with timestamp indicators showing data freshness. Support 170+ global currencies including crypto with appropriate symbols and formatting. Maintain a conversion history log with timestamps and rate information. Allow users to bookmark favorite currency pairs for quick access. Generate interactive historical rate charts with customizable date ranges. Implement offline functionality using cached exchange rates with clear staleness indicators. Add a built-in calculator for complex conversions and arithmetic operations. Create rate alerts for target exchange rates with optional notifications. Include side-by-side comparison of different provider rates when available. Support printing and exporting conversion results in multiple formats (PDF, CSV, JSON).

Create a client-side file encryption tool using HTML5, CSS3, and JavaScript with the Web Crypto API. Build a drag-and-drop interface for file selection with progress indicators. Implement AES-256-GCM encryption with secure key derivation from passwords (PBKDF2). Add support for encrypting multiple files simultaneously with batch processing. Include password strength enforcement with entropy calculation. Generate downloadable encrypted files with custom file extension. Create a decryption interface with password verification. Implement secure memory handling with automatic clearing of sensitive data. Add detailed logs of encryption operations without storing sensitive information. Include export/import of encryption keys with proper security warnings. Support for large files using streaming encryption and chunked processing.

Build a developer-focused code snippet manager using HTML5, CSS3, and JavaScript. Create a clean IDE-like interface with syntax highlighting for 30+ programming languages. Implement a tagging and categorization system for organizing snippets. Add a powerful search function with support for regex and filtering by language/tags. Include code editing with line numbers, indentation guides, and bracket matching. Support public/private visibility settings for each snippet. Implement export/import functionality in JSON and Gist formats. Add keyboard shortcuts for common operations. Create a responsive design that works well on all devices. Include automatic saving with version history. Add copy-to-clipboard functionality with syntax formatting preservation.