A calming sleep-tracking feature screenshot presented inside a slim, modern smartphone mockup. Build a clean mobile app interface with the App Name at the top and the Sleep Metrics rendered exactly as written in a quiet, readable hierarchy. Make the main focus a smooth sleep graph showing an overnight timeline with distinct light, deep and REM phases, rounded data points, subtle grid lines and a clear progress summary. Use generous spacing, softly rounded cards and restrained interface details so the graph remains instantly understandable. Place the phone upright against the Background Color, with a faint ambient glow and a soft contact shadow beneath it. Keep the composition centered with ample breathing room, gentle diffused lighting and a refined wellness-app feel. Do not add any other legible text. Render the final image in the Format.
Use these details:
App Name: "Nox"
Sleep Metrics: ["8h 12m asleep", "92 sleep score", "Deep sleep 1h 48m", "REM 2h 06m"]
Background Color: "soft lavender purple"
Format: "9:16 vertical"
