From Tailwind release:

Tailwind CSS v3.0 is here — bringing incredible performance gains, huge workflow improvements, and a seriously ridiculous number of new features.

Read the announcement post for all the details.

Added

• Add colored box shadow utilities (#5979)
• Add native aspect-ratio utilities (#5359)
• Add column utilities (#5457)
• Add break-before, break-inside and break-after utilities (#5530)
• Add text-indent utilities (#5449)
• Add text-decoration-{color/style/thickness/offset} utilities (#5760, #6004)
• Add outline-style, outline-color, outline-width and outline-offset utilities (#5887)
• Add align-sub and align-super vertical-align utilities (#5486)
• Add accent-color utilities (#5387)
• Add scroll-snap utilities (#5637)
• Add scroll-behavior utilities (#5388)
• Add touch-action utilities (#5603, #6115)
• Add flex-basis utilities (#5671)
• Add grow-* and shrink-* utilities, deprecate flex-grow-* and flex-shrink-* (#5733)
• Add border-x and border-y width and color utilities (#5639)
• Add border-hidden utility (#5485)
• Add overflow-clip, overflow-x-clip and overflow-y-clip utilities (#5630)
• Add inherit to default color palette (#5597)
• Add full color palette for fill-* and stroke-* utilities (#5933)
• Add fit-content values for min/max-width/height utilities (#5638)
• Add min/max-content values for min/max-height utilities (#5729)
• Add will-change utilities (#5448)
• Add all standard cursor-* values by default (#5734)
• Add print variant for targeting printed media (#5885)
• Add placeholder variant (#6106)
• Add file variant for ::file-selector-button pseudo element (#4936)
• Add [open] variant (#5627)
• Add portrait and landscape variants (#6046)
• Add menu reset to preflight (#6213)
• Add comprehensive "arbitrary value" support (#5568, #6233, #6259, #6258, #6283)
• Add "arbitrary properties" support (#6161)
• Add first-class negative value support (#5709, c48e629)
• Add new declarative addVariant API (#5809)

Changed

• Remove AOT engine, make JIT the default (#5340)
• Enable extended color palette by default with updated color names (#5384)
• Rename overflow-clip to text-clip and overflow-ellipsis to text-ellipsis (#5630)
• Deprecate decoration-slice and decoration-break in favor box-decoration-slice and box-decoration-break (#6004)
• Move vertical-align values to config file instead of hard-coding (#5487)
• Throw when trying to @apply the group class (#4666)
• Remove dependency on modern-normalize, inline and consolidate with Preflight (#5358)
• Remove prefix as a function (#5829)
• Don't use pointer cursor on disabled buttons by default (#5772)
• Set default content value in preflight instead of within each before/after utility (#5820)
• Preserve original color format when adding opacity whenever possible (#5154)
• Unify config callback helpers into single object (#5382)