Problem:
Various Zabbix themes are affected by text and UI component color contrast problems, which should be addressed to comply with accessibility requirements.

Blue theme

1. The current color #768D99 used for components and text fails to meet minimum accessibility contrast requirements. It's recommend to replacing it system-wide with the darker alternative #5E7581, which achieves the required contrast ratio of 4.84:1.
2. Icons using background color #B0BEC5 do not provide sufficient contrast against white backgrounds. This should be updated to the darker shade #777F83 throughout the system, which meets accessibility requirements with a 4.84:1 contrast ratio in all color combinations.
3. The green color elements with value #429E47 (green, .green.btn-icon:not([disabled]), .green.btn-link:not([disabled]), .green.link-action:not(:hover):not(:focus), .green.link-alt:not(:hover):not(:focus)) also fails color contrast requirements. Recommended replacement is #1D7F22.
4. The red color elements with value #e33734 (.color-negative, .color-negative.btn-icon:not([disabled]), .color-negative.btn-link:not([disabled]), .color-negative.link-action:not(:hover):not(:focus), .color-negative.link-alt:not(:hover):not(:focus), .red, .red.btn-icon:not([disabled]), .red.btn-link:not([disabled]), .red.link-action:not(:hover):not(:focus), .red.link-alt:not(:hover):not(:focus)) do not meet color contrast requirements. Recommended replacement #d7322f.

Blue theme UI before (with problems):

Updated Blue theme after:

Dark theme

1. Links and link buttons with value #4796C4 do not meet minimum color contrast requirements. Recommended replacement #46A0D4.
2. Solid action buttons do no meet color contrast requirements. It is recommended to change existing bg/border = #69808D to #58707B, hover state - bg/border = #5e737e to #506670.
3. Outline action buttons do no meet color contrast requirements. It is recommended to change existing border color = #69808D to #58707B, Hover state bg/border = #5e737e to #506670.
4. Text and link buttons with color #737373 do not meet color contrast requirements, recommended alternative #969696 (ex. Data collection → Hosts → Proxy/Templates columns)

Dark theme before:

Dark theme after:

High-contrast light

1. The green color elements with value #009900 (.green, .green.btn-icon:not([disabled]), .green.btn-link:not([disabled]), .green.link-action:not(:hover):not(:focus), .green.link-alt:not(:hover):not(:focus), .color-positive, .color-positive.btn-icon:not([disabled]), .color-positive.btn-link:not([disabled]), .color-positive.link-action:not(:hover):not(:focus), .color-positive.link-alt:not(:hover):not(:focus)) fails color contrast requirements. Recommended alternative #1D7F22.

High-contrast light before:

High-contrast light after:

Expected result:
Improved readability and accessibility.

Benefits:
Improving color contrast will make the product easier to read and navigate for everyone, supporting users with low vision or color blindness, and ultimately increasing usability and trust in the platform.