Web Design Leaves

<div class="flex_container_fill">
  <div class="flex_item_fill">Flex item</div>
  <div class="flex_item_fill">Flex item</div>
  <div class="flex_item_fill">Flex item</div>
</div> 

.flex_container_fill {
  display: flex;
  flex-direction: row;
  max-width: 670px;
}
.flex_item_fill {
  flex: 1 1 auto;
  margin: 5px;
  padding: 5px;
}

<div class="flex_container_fill">
  <div class="flex_item_fill">Flex item</div>
  <div class="flex_item_fill">Flex item (Extra content)</div>
  <div class="flex_item_fill">Flex item</div>
</div> 

<div class="d-flex">
  <div>Flex item</div>
  <div>Flex item</div>
  <div>Flex item</div>
</div>

<div class="d-flex">
  <div style="margin-right: auto;">Flex item</div>
  <div>Flex item</div>
  <div>Flex item</div>
</div>

<div class="d-flex">
  <div>Flex item</div>
  <div>Flex item</div>
  <div style="margin-left: auto;">Flex item</div>
</div>

.d-flex {
  display: flex;
}  

<div class="d-flex-column-start" style="height: 160px;">
  <div style="margin-bottom: auto;">Flex item</div>
  <div>Flex item</div>
  <div>Flex item</div>
</div>

<div class="d-flex-column-end" style="height: 160px;">
  <div>Flex item</div>
  <div>Flex item</div>
  <div style="margin-top: auto;">Flex item</div>
</div>

.d-flex-column-start {
  display: flex;
  flex-direction:column;
  align-items:flex-start
}
.d-flex-column-end {
  display: flex;
  flex-direction:column;
  align-items:flex-end;
} 

<div class="container">
  <section class="main">
    <h1>Main</h1>
    <p> Lorem ipsum dolor sit amet, consectetur adipisicing elit. Magnam totam....</p>
  </section>
  <section class="side">
    <h2>Side</h2>
    <p>A, unde, voluptas, explicabo, est placeat molestias...</p>
  </section>
</div> 

* {
  margin:0;
  padding:0;
  box-sizing: border-box;
}
.container {
  margin: 40px auto 0;
  max-width: 1060px;
  position: relative;
}
.main {
  background: #BFF2F7;
}
.side {
  background: #FCE1E2;
}
.main,
.side {
  padding: 2%;
}

/* Responsive */
@media ( min-width : 576px ){
.container {
  display: flex;
}
.main {
  margin: 0 10px 0 0;
  flex: 1 1 auot;
}
.side {
  flex: 0 0 300px;
}

@media ( min-width : 576px ){
  .container {
    display: flex;
  }
  .main {
    margin: 0 10px 0 0;
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: calc(70% - 10px);
  }
  .side {
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: 30%;
  }
}

@media ( min-width : 576px ){
  .container {
    display: flex;
  }
  .main {
    margin: 0 0 0 10px;　/*　変更　*/
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: calc(70% - 10px);
  }
  .side {
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: 30%;
    order: -1;　/*　追加　*/
  }
}

<div class="container">
  <section class="side1">
    <h2>Side1</h2>
    <p>A, unde, voluptas, explicabo, est placeat molestias...</p>
  </section>
  <section class="main">
    <h1>Main</h1>
    <p> Lorem ipsum dolor sit amet, consectetur adipisicing elit....</p>
  </section>
  <section class="side2">
    <h2>Side2</h2>
    <p>Aut, dolores dolorem totam sunt consequuntur ipsam...</p>
  </section>
</div>  

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.container {
  margin: 40px auto 0;
  max-width: 1060px;
  position: relative;
}
.main, .side1, .side2 {
  padding: 2%;
}

@media ( min-width : 576px ) {
  .container {
    display: flex;
  }
  .main {
    margin: 0 10px 0;
    flex: 1 1 auto;
  }
  .side1 {
    flex: 0 0 240px;
  }
  .side2 {
    flex: 0 0 180px;
  }
}

@media ( min-width : 576px ) {
  .container {
    display: flex;
  }
  .main {
    margin: 0 10px 0;
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: calc(55% - 20px);
  }
  .side1 {
    flex-grow: 0;
    flex-shrink: 0;
    flex-basis: 25%;
  }
  .side2 {
    flex-grow: 0;
    flex-shrink: 0;
    flex-basis: 20%;
  }
}

@media ( min-width : 576px ) {
  .container {
    display: flex;
  }
  .main {
    margin: 0 10px 0;
    flex:2;
  }
  .side1 {
    flex:1;
  }
  .side2 {
    flex:1;
  }
}

@media ( min-width : 576px ) {
  .container {
    display: flex;
  }
  .main {
    margin: 0 10px 0;
    flex-grow: 2;
    flex-shrink: 1;
    flex-basis: 0;
  }
  .side1 {
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: 0;
  }
  .side2 {
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: 0;
  }
}

@media ( min-width : 576px ) {
  .container {
    display: flex;
  }
  .main {
    margin: 0 10px 0 0;
    flex:2;
    order:1;
  }
  .side1 {
    margin-right: 10px;
    flex:1;
    order:2;
  }
  .side2 {
    flex:1;
    order:3;
  }
}

<div class="row">
  <div class="col">col 1</div>
  <div class="col">col 2</div>
  <div class="col">col 3</div>
</div>
<div class="row">
  <div class="col">col 1</div>
  <div class="col">col 2</div>
  <div class="col">col 3</div>
  <div class="col">col 4</div>
</div>
<div class="row">
  <div class="col">col 1</div>
  <div class="col">col 2</div>
  <div class="col">col 3</div>
  <div class="col">col 4</div>
  <div class="col">col 5</div>
</div>

.row {
  display: flex;
  margin-left: -20px;
}
.col {
  width: 100%;
  margin-left: 20px;
  height: 60px;
}

<div class="container">
  <div class="flex_container">
    <div class="flex_item"><h3>Flex Item 1</h3>
      <img src="http://via.placeholder.com/240x160" alt="" />
      <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit...</p>
    </div>
    <div class="flex_item"><h3>Flex Item 2</h3>
      <img src="http://via.placeholder.com/240x160" alt="" />
      <p>Magnam totam saepe provident cum suscipit explicabo architecto earum necessitatibus nam corporis?.</p>
    </div>
    ...中略...
    <div class="flex_item"><h3>Flex Item 10</h3>
      <img src="http://via.placeholder.com/240x160" alt="" />
      <p>Fuga commodi qui maiores accusantium provident ullam magnam ipsam quos., consectetur adipiscing elit...</p>
    </div>
    <div class="flex_item"></div>
    <div class="flex_item"></div>
  </div>
</div>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.container {
  margin: 10px auto 0;
  max-width: 1060px;
  position: relative;
}
.flex_item {
  margin-bottom: 10px;
  text-align: center;
}
.flex_item img {
  margin: 10px;
  width: 90%;
  max-width: 240px;
}
.flex_item:empty {
  border: none;
  background: none;
}

@media ( min-width : 576px ) {
  .flex_container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
  }
  .flex_item {
    flex: 0 0 24%;
  }
}

.flex_item img {
  margin: 10px;
}

@media ( min-width : 576px ) {
  .flex_container {
    display: flex;
    flex-wrap: wrap;
    /*justify-content: space-around;*/
  }
  .flex_item {
    flex: 1 0 220px;　/* flex-basis を px で指定 */
    margin: 0 5px 10px;
  }
}

<div class="flex_container">
  <div class="flex_item"> <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 1</h3>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit...</p>
    <a href="#" class="button">Contact</a> </div>
  <div class="flex_item"> <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 2</h3>
    <p>Magnam totam saepe provident cum suscipit explicabo ......</p>
    <a href="#" class="button">Contact</a> </div>
  <div class="flex_item"> <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 3</h3>
    <p> Fuga commodi qui maiores accusantium provident ullam magnam .......</p>
    <a href="#" class="button">Contact</a> </div>
  <div class="flex_item"> <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 4</h3>
    <p>A, unde, voluptas, explicabo, est placeat molestias dignissimos ......</p>
    <a href="#" class="button">Contact</a> </div>
</div>
<div class="flex_container">
  <div class="flex_item"> <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 5</h3>
    <p>nulla ipsa voluptatum laboriosam optio perspiciatis .......</p>
    <a href="#" class="button">Contact</a> </div>
  　・・・中略・・・
</div> 

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.button {
  margin: auto auto 10px;  /* margin-top を auto に指定　*/
  padding: 5px 10px;
  display: block;
  width: 120px;
}
.container {
  margin: 40px auto 0;
  max-width: 1060px;
  position: relative;
}
.flex_item {
  margin-bottom: 10px;
}
.flex_item img {
  margin: 10px auto;
  width: 100%;
  max-width: 240px;
}
.flex_item:empty {
  border: none;
  background: none;
}

@media ( min-width : 576px ) {
  .flex_container {
    display: flex;
    justify-content: space-around;
  }
  .flex_item {
    flex: 0 0 24%;
    margin: 0 5px 10px;
    display: flex; /* 入れ子になった Flex コンテナ　*/
    flex-direction: column; /* 子要素を縦に並べる　*/
  }
}

<div class="flex_container">
  <div class="flex_item">
    <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 1</h3>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit...</p>
    <a href="#" class="button">Contact</a>
  </div>
  <div class="flex_item">
    <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 2</h3>
    <p>Magnam totam saepe provident cum suscipit explicabo architecto.....</p>
    <a href="#" class="button">Contact</a>
  </div>
  <div class="flex_item">
    <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 3</h3>
    <p> Fuga commodi qui maiores accusantium provident ullam magnam .....</p>
    <a href="#" class="button">Contact</a>
  </div>
  ・・・中略・・・
  <div class="flex_item">
    <img src="http://via.placeholder.com/240x160" alt="" />
    <h3>Flex Item 10</h3>
    <p>Fuga commodi qui maiores accusantium provident ullam magnam ipsam quos.....</p>
    <a href="#" class="button">Contact</a>
  </div>
  <div class="flex_item"></div>
  <div class="flex_item"></div>
</div>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.button {
  display: block;
  width: 120px;
  margin: auto auto 10px;
}
.container {
  margin: 40px auto 0;
  max-width: 1060px;
  position: relative;
}
.flex_item {
  margin-bottom: 10px;
}
.flex_item img {
  margin: 10px auto;
  width: 100%;
  max-width: 240px;
}
.flex_item:empty {
  border: none;
  background: none;
}

@media ( min-width : 576px ) {
  .flex_container {
    display: flex;
    flex-wrap: wrap;  /* 折り返し表示 */
    justify-content: space-around;
  }
  .flex_item {
    flex:1 0 240px;
    margin: 0 5px 10px;
    display: flex;
    flex-direction: column;
  }
}

<nav>
  <ul>  <!-- Flex コンテナ（ul 要素）  -->
    <li><a href="#">Home</a></li>   <!-- Flex アイテム（li 要素）  -->
    <li><a href="about/">About</a></li>
    <li><a href="news/">News</a></li>
    <li><a href="events/">Events</a></li>
    <li><a href="contact/">Contact</a></li>
  </ul>
</nav>

* {
  margin: 0;
  padding: 0;
}
nav {
  background: #EEEEEE;
  border-bottom: 5px solid #689CC7;
}
nav ul {
  display: flex;  /* 親要素に「display: flex;」を指定 */
  list-style: none;
  margin: 0;
  padding: 10px 10px 0 10px;
}
nav li a {
  display: block;
  padding: 10px 20px;
  text-decoration: none;
  font-size: 16px;
  color: #333333;
}
nav li a:hover {
  background: #689CC7;
  color: #E0F6F7;
}

nav ul { /*  Flex コンテナ（ul 要素）*/
  display: flex;
  justify-content: flex-start;
  list-style: none;
  margin: 0;
  padding: 10px 10px 0 10px;
}

nav {
  background: #EEEEEE;
  border-bottom: 5px solid #689CC7;
}

nav ul {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 10px 10px 0 10px;
}

/* Flex アイテムに「flex-grow: 1」を指定 */
nav li {
  flex-grow: 1;
}

nav li a {
  display: block;
  padding: 10px 20px;
  text-decoration: none;
  font-size: 16px;
  color: #333333;
  text-align: center;  /* テキストを中央寄せ */
}

nav li a:hover {
  background: #689CC7;
  color: #E0F6F7;
}

<nav>
  <ul>
    <li class="home"><a href="#">Home</a></li>
    <li><a href="#">About</a></li>
    <li><a href="#">News</a></li>
    <li><a href="#">Events</a></li>
    <li class="contact"><a href="#">Contact</a></li>
  </ul>
</nav>

* {
  margin: 0;
  padding: 0;
}
nav {
  background: #EEEEEE;
  border-bottom: 5px solid #689CC7;
}
nav ul {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 10px 10px 0 10px;
}

nav li a {
  display: block;
  padding: 10px 20px;
  text-decoration: none;
  font-size: 16px;
  color: #333333;
  text-align: center;
}
nav li a:hover {
  background: #689CC7;
  color: #E0F6F7;
}

nav li.contact {
  margin-left: auto;
}

<header>
  <h1>Site Title</h1>
  <div class="search">
    <form>
      <input type="text" name="search"><input type="submit" value="検索">
    </form>
  </div>
</header> 

header {
	display: flex;
	max-width: 1060px;
	margin: 30px auto;
}

.search {
	margin-top: auto;
	margin-left: auto;
}

h1 {
  font-size: 36px;
  height: 36px;
}

<div class="wrapper">
  <div class="center">
    <p>Lorem ipsum dolor sit amet</p>
  </div>
</div>  

.wrapper {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 300px;
  height: 300px;
  margin: 30px auto;
  border: 1px solid #ccc;
}
.center {
  border: 1px solid #999;
  background-color: #E2F7DF;
  padding: 20px;
  height: 100px;
  width: 100px;
  text-align: center;
}

.center {
  border: 1px solid #999;
  background-color: #E2F7DF;
  padding: 20px;
  height: 100px;
  width: 100px;
  text-align: center;
  display: flex;   /*  追加  */
  align-items: center; /*  追加  */
}