Material theme for Mattermost (Mattermost -> Account Settings ->Display -> Theme -> Copy to related input)

mattermost-material-theme.txt

{"sidebarBg":"#263238","sidebarText":"#FFFFFF","sidebarUnreadText":"#FFFFFF","sidebarTextHoverBg":"#13191C","sidebarTextActiveBorder":"#80CBC4","sidebarTextActiveColor":"#FFFFFF","sidebarHeaderBg":"#2E3A40","sidebarHeaderTextColor":"#FFFFFF","onlineIndicator":"#50FA7B","awayIndicator":"#E0B333","dndIndicator":"#F74343","mentionBg":"#13191C","mentionBj":"#13191C","mentionColor":"#FFFFFF","centerChannelBg":"#13191C","centerChannelColor":"#FFFFFF","newMessageSeparator":"#f80","linkColor":"#2389D7","buttonBg":"#26A970","buttonColor":"#FFFFFF","errorTextColor":"#FD5960","mentionHighlightBg":"#2E3A40","mentionHighlightLink":"#2F81B7","codeTheme":"solarized-dark"}

Here the colors for the ocean theme (probably not perfect):

{
  "sidebarBg": "#0f111a",
  "sidebarText": "#a6accd",
  "sidebarUnreadText": "#82aaff",
  "sidebarTextHoverBg": "#292d3e",
  "sidebarTextActiveBorder": "#80cbc4",
  "sidebarTextActiveColor": "#80cbc4",
  "sidebarHeaderBg": "#0f111a",
  "sidebarHeaderTextColor": "#a6accd",
  "onlineIndicator": "#82aaff",
  "awayIndicator": "#ffcb6b",
  "dndIndicator": "#f07178",
  "mentionBg": "#0f111a",
  "mentionBj": "#0f111a",
  "mentionColor": "#a6accd",
  "centerChannelBg": "#0f111a",
  "centerChannelColor": "#828ead",
  "newMessageSeparator": "#ffcb6b",
  "linkColor": "#80cbc4",
  "buttonBg": "#717cb4",
  "buttonColor": "#ffffff",
  "errorTextColor": "#f07178",
  "mentionHighlightBg": "#2e3a40",
  "mentionHighlightLink": "#80cbc4",
  "codeTheme": "solarized-dark",
  "key": "#ffffff"
}