github页面jekyll-可以从主题覆盖CSS

Question

只是为了序言，我对前端很糟糕，我正在学习Ruby/Jekyll。

我在GitHub页面网站上工作，我正在尝试覆盖我使用的Jekyll主题的某些CSS类。

我已经创建了一个带有自定义CSS类的表，我要做的就是摆脱该桌子上的边框。

.portfolio-table td {
  font-size: 14px;
  overflow: hidden;
  padding: 10px 5px;
  word-break: normal;
}
.portfolio-table th {
  font-size: 14px;
  font-weight: normal;
  overflow: hidden;
  padding: 10px 5px;
  word-break: normal;
}
.portfolio-table .portfolio-table-text-header {
  font-weight: bold;
  text-align: left;
  vertical-align: top;
}
.portfolio-table .portfolio-table-text-body {
  color: #9b9b9b;
  text-align: left;
  vertical-align: top;
}
.portfolio-table .portfolio-table-header,
.portfolio-table .portfolio-table-image,
.portfolio-table .portfolio-table-button {
  text-align: left;
  vertical-align: top;
}

<table class="portfolio-table" style="border: 0px transparent #ffffff;">
            <tbody>
                <tr>
                    <td class="portfolio-table-image"><img
                            src="data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 512 512'%3e%3cpath fill='%23000000' d='M157.52 272h36.96L176 218.78 157.52 272zM352 256c-13.23 0-24 10.77-24 24s10.77 24 24 24 24-10.77 24-24-10.77-24-24-24zM464 64H48C21.5 64 0 85.5 0 112v288c0 26.5 21.5 48 48 48h416c26.5 0 48-21.5 48-48V112c0-26.5-21.5-48-48-48zM250.58 352h-16.94c-6.81 0-12.88-4.32-15.12-10.75L211.15 320h-70.29l-7.38 21.25A16 16 0 0 1 118.36 352h-16.94c-11.01 0-18.73-10.85-15.12-21.25L140 176.12A23.995 23.995 0 0 1 162.67 160h26.66A23.99 23.99 0 0 1 212 176.13l53.69 154.62c3.61 10.4-4.11 21.25-15.11 21.25zM424 336c0 8.84-7.16 16-16 16h-16c-4.85 0-9.04-2.27-11.98-5.68-8.62 3.66-18.09 5.68-28.02 5.68-39.7 0-72-32.3-72-72s32.3-72 72-72c8.46 0 16.46 1.73 24 4.42V176c0-8.84 7.16-16 16-16h16c8.84 0 16 7.16 16 16v160z'/%3e%3c/svg%3e"
                            alt="Image" width="100" height="100"></td>
                    <td class="portfolio-table-image"><img
                            src="data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 512 512'%3e%3cpath fill='%23000000' d='M157.52 272h36.96L176 218.78 157.52 272zM352 256c-13.23 0-24 10.77-24 24s10.77 24 24 24 24-10.77 24-24-10.77-24-24-24zM464 64H48C21.5 64 0 85.5 0 112v288c0 26.5 21.5 48 48 48h416c26.5 0 48-21.5 48-48V112c0-26.5-21.5-48-48-48zM250.58 352h-16.94c-6.81 0-12.88-4.32-15.12-10.75L211.15 320h-70.29l-7.38 21.25A16 16 0 0 1 118.36 352h-16.94c-11.01 0-18.73-10.85-15.12-21.25L140 176.12A23.995 23.995 0 0 1 162.67 160h26.66A23.99 23.99 0 0 1 212 176.13l53.69 154.62c3.61 10.4-4.11 21.25-15.11 21.25zM424 336c0 8.84-7.16 16-16 16h-16c-4.85 0-9.04-2.27-11.98-5.68-8.62 3.66-18.09 5.68-28.02 5.68-39.7 0-72-32.3-72-72s32.3-72 72-72c8.46 0 16.46 1.73 24 4.42V176c0-8.84 7.16-16 16-16h16c8.84 0 16 7.16 16 16v160z'/%3e%3c/svg%3e"
                            alt="Image" width="100" height="100"></td>
                </tr>
                <tr>
                    <td class="portfolio-table-text-header">LEAN STARTUP PRODUCT DEVELOPMENT</td>
                    <td class="portfolio-table-text-header">IMPLEMENTING AGILE - KANBAN &amp; SCRUM</td>
                </tr>
                <tr>
                    <td class="portfolio-table-text-body">Lunna is an app that provides assistance on women's
                        health. The app learns about user choices, preferences, and symptoms using machine learning;
                        allowing the user to improve life quality. Developed an MVP (minimum viable product) and
                        ready to scale version of the app in React Native and Elixir. Ran 2+ workshops during design
                        and also development phases</td>
                    <td class="portfolio-table-text-body">SoFi is an online personal finance company. I managed the
                        projects with a team of 30+ people. Including designers, copywriters, product marketing
                        managers and sales teams ofdifferent areas. Delivered 94 projects within a month including
                        billboards, social media campaigns,TV and YouTube commercials, eCRM campaigns, and events
                        for different marketing campaigns.</td>
                </tr>
                <tr>
                    <td class="portfolio-table-button">BUTTON</td>
                    <td class="portfolio-table-button">BUTTON</td>
                </tr>
            </tbody>
        </table>

该表通过此表很好地生成，边框没有显示。但是它包含在＆lt; main ID =“ content” class =“ main-content”角色=“ main”＆gt;标签中，将CSS规则从jekyll的主题中带入其中。

我已经尝试过！html中重要的，内联CSS，样式标签。我尝试过的任何事情都无法摆脱这个边界。