CSS Design Notes

CSS Framework Key Points

• Design tokens.
• Content.
• Centering.
• Spacing.
• Color and contrast.
• Balance (position).
• Primary and secondary color.
• Custom text (font).
• Font family.
• Images and links.

Typography Principles

• The typeface (font-family).
• Type (modular) scale.
• Responsiveness of the text (size unit and breakpoints).
• Spacing and vertical rhythm.
• Colors (theming).

Refer to: font-family, font-size, spacing, color.

Typography Properties

Font Size

• Set a base-size.
• Multiples of base-size.
• Use rem for most font-size, use em for some spacing (needing responsive design).
• rem is better.
• em for responsive layout: e.g layer2 font based-on layer1 font in dropdown menu.
• Make text legible: at least 16px.

$xs: $base / $ratio / $ratio;
$sm: $base / $ratio;
$md: $base;
$lg: $base * $ratio;
$xl: $base * $ratio * ratio;

Spacing

Make text breathe:

• margin/padding: at least 15px.
• line-height: 1.4.
• word-spacing.
• letter-spacing.
• 60-100 characters per line.

Vertical Rhythms

Keep vertical spaces between elements on a page consistent (and relative) to each other:

• Set the vertical white space between elements to a multiple of base-size.
• Set the line-height of all text elements to a multiple of base-size.
• Set margin-top and margin-bottom to <h1> ~ <h6>/<hr> elements set margin-bottom to normal elements.

Line Length

The optimal line length for body text is 50–75 characters:

• Shorter or longer line lengths can hurt readability.

.line-length {
  margin-top: 2em;
  line-height: 1.5em;
  letter-spacing: 0.12em;
  word-spacing: 0.16em;
}

Table Typography

• Remove fills, grid lines, border and bolding.
• Left-align text, right-align numbers and align headings with data.
• Put white space to work to group and separate.

Typography Reference

• Understanding typography guide.
• Practical typography guide.
• Golden rules of web typography reference.
• Typeface font matrix.

Responsive Design

Responsive web design:

• Mobile first: @media only screen and (min-width: 768px).
• Media query.
• Fluid layout.
• Flexible image.

Mobile Viewport

Disable mobile browser auto scale:

<meta name="viewport" content="width=device-width, initial-scale=1" />

Responsive Font

• rem/em font size.

Responsive Length

• vw.
• vh.
• vmin: min(vw, vh).
• vmax: max(vw, vh).

Responsive Size

Responsive font size;

• Size in em if the property scales according to it's font-size: e.g button padding.
• Modular font size: Size in em if the font-size should be modular (relative to it's context/parent).
• Size everything else in rem (include @media queries).

/* scales to self font-size */
.container {
  margin-top: 1.2em;
}

/* modular font size */
.container {
  font-size: 1.2rem;
}

.container p {
  font-size: 1em;
}

.container small {
  font-size: 0.9em;
}

Responsive Box

Responsive Width and Height

• min-height.
• max-height.
• min-width.
• max-width.

/* responsive images */
img {
  display: block;
  max-width: 100%;
}

Image Display

Image display set to inline default.

Responsive Inline Box

use inline-box with width

.element {
  display: inline-box;
  width: 80%;
}

Responsive Flex Box

.box {
  display: flex;
  flex-wrap: wrap;
}

.box > .item {
  flex: 1;
}

Responsive Grid Box

.box {
  display: grid;
  grid-template-areas:
    'hd'
    'st1'
    '.'
    'st2'
    '.';
  grid-template-columns: 1fr;
}

@media only screen and (width >= 768px) {
  .box {
    grid-template-areas:
      'hd hd'
      'st1 .'
      '. st2';
    grid-template-columns: 1fr 1fr;
  }
}

@media only screen and (width >= 1280px) {
  .box {
    grid-template-areas:
      'hd hd hd'
      'st1 . st2'
      'st1 . st2';
    grid-template-columns: 1fr 1fr 1fr;
  }
}

@media only screen and (width >= 1536px) {
  .box {
    grid-template-areas:
      'hd st1 . st2'
      'hd st1 . st2';
    grid-template-columns: 20% 1fr 1fr 1fr;
  }
}

Responsive Image

.responsive-image {
  display: block;
  max-width: 100%;
  height: auto;
}

<picture>
  <source srcset="mdn-logo-wide.png" media="(min-width: 600px)" />
  <img src="mdn-logo-narrow.png" alt="MDN" />
</picture>

<img src="x-small.png" srcset="x-small.png 300w, small.png 400w, medium.png
600w, large.png 800w, x-large.png 1200w" sizes="(min-width: 70em) 12.6875em,
(min-width: 50em) calc(25vw * 0.95 - 2.75em), (min-width: 35em) calc(95vw / 2 -
4.125em), calc(95vw - 1.375em)" " alt="Dummy Image" />

Responsive Table

table {
  width: 100%;
}

@media (width <= 30em) {
  table,
  thead,
  tbody,
  tr,
  th,
  td {
    display: block;
  }

  tr {
    margin-bottom: 1em;
  }

  /* 隐藏表头 */
  thead tr {
    position: absolute;
    top: -9999px;
    left: -9999px;
  }
}

Design Principles

Cicada Principle

禅原则:

当用户注意到一个有辨识度的特征 (比如木纹上的节疤) 在以固定的规律循环重复时, 那它试图营造的自然随机性就会立刻崩塌. 使用 CSS 实现形状时, 应尽可能地重现大自然的随机性.

Fitts Law

费茨定律:

人机交互和人体工程学中人类活动的模型, 它预测了从任意位置快速移动到一个目标位置所需的时间, 由 2 个位置的距离（D）和目标大小（S）有关, 正比于 D, 反比于 S:

• 关联性强的 UI 放置在一起.
• 大拇指点击热区.
• 屏幕边界视为无限大 (容易到达).
• 关机滑动距离长.
• 利用透明边框或伪元素扩大可点击区域 (hit area).

米勒定律

人的短时记忆能力广度为 7±2 个信息块:

• 手机号/银行卡号/超大数字分段放置, 信息分层 e.g 134 9999 9999, 999, 999, 999.
• 文章布局时增大段落间 margin, 改变部分文字的粗细/字体/颜色.
• 导航/选项卡不超过 9 个 (超过 9 个可使用 dropdown/subMenu).

席克定律

用户所面临的选择数量越多, 做出选择所花费的时间就越长, 在人机交互的界面中选项越多, 意味着用户做出决策的时间越长:

• 减少选项并提供默认值.
• 分类分层.
• 分步分页 (大部分手机应用注册界面).

泰斯勒定律

泰斯勒定律又称复杂性守恒定律, 该定律认为每一个过程都有其固有的复杂性, 这个复杂性存在一个临界点, 超过了这个点就不能再简化了, 你只能将固有的复杂性从一个地方移动到另外一个地方:

• 智能手机: 按键的复杂度转为手机操作系统的复杂度.
• 智能推荐: 用户自己选择筛选条件的复杂度转为人工智能算法的复杂度.

Components Design Principles

• UX Checklist
• Components Checklist
• Accordion
• Responsive Configurator
• DateTime Picker
• Feature Comparison Table
• Slider
• Birthday Picker
• Mega Dropdown
• Frozen Filter
• Disabled Button
• Infinite Scroll
• Breadcrumbs
• Push Notification
• Carousel
• Navigation
• Language Selector
• Data Visualization
• Pricing Page
• Authentication Page
• Back Button
• Error Message
• Inline Validation

HomePage User Experience

UX research point out that:

• Feature a Broad Range of Product Types (6% Don’t).
• Avoid Overly Aggressive and Distracting Ads (59% Don’t).
• Implement Carousels Carefully (75% Don’t).
• Assist the Selection of a Well-Defined Scope (62% Don’t).
• Invest in Bespoke Imagery and Design (19% Don’t).
• Make the Search Field Immediately Obvious (22% Don’t).
• Implement Country & Language Selection Carefully (35% Don’t).
• Ensure Visual Hit Areas Match the Actual Hit Areas (43% Don’t).

Form Design Principles

• Form design blog.
• Form design book.

Buttons Placement Principles

Principles:

• Align the primary button to the left edge of the inputs.
• Put the back button above the form.
• Put tangentially related actions above the form.
• Place extra buttons based on what they do.
• In some single field forms put the button next to the input (e.g search button).
• Put buttons on multi select forms above the form.