html {
    background: #000000;
    -webkit-font-smoothing: antialiased;
}
<style>
@import url('https://fonts.googleapis.com/css2?family=M+PLUS+1p&family=Roboto&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');
</style>


/* スクロールの幅の設定 */
html::-webkit-scrollbar {
  width: 15px;
  height: 10px;
}

/* スクロールの背景の設定 */
html::-webkit-scrollbar-track {
  border-radius: 5px;
  box-shadow: 0 0 4px yellow inset;
}

/* スクロールのつまみ部分の設定 */
html::-webkit-scrollbar-thumb {
  border-radius: 5px;
  background: #ff5500;
}
body {
    background: #232323;
    box-shadow: 0 0 2px rgba(0, 0, 0, 0.06);
    color: gold;
    font-family: 'M PLUS 1p',"メイリオ",sans-serif;
    //font-family:"Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 16px;
    line-height: 1.5;
    margin: 0 auto;
    max-width: 800px;
    padding: 1em 2em 4em;    
}

footer{
    
}

h1, h2, h3, h4, h5, h6 {
    color: gold;
    font-weight: 600;
    line-height: 1.3;
    text-align: center;
    font-family: 'Roboto',"メイリオ",sans-serif;
}

h2 {
    margin-top: 1.3em;
}

hr{
	position: relative;
	height: 0.5em;
	border-width: 0;
	background-color: gold;
	background-image: -webkit-linear-gradient(left,
	red 0%,gold 50%,red 100%);
	background-image:         linear-gradient(90deg,
	red 0%,gold 50%,red 100%);
}
hr.foot{
    margin-top: 6em;
    margin-bottom: 6em;
}
a.fx1 {
      color: #ff5500;
      text-decoration: none;
      padding: 0 10px;
      background-image: linear-gradient(to right, rgba(0, 0, 0, 0) 50%, rgb(255, 192, 0) 50%);
      background-position: 0 0;
      background-size: 200% auto;
      transition: .3s;
}
a.fx1:hover {
    background-position: -100% 0;
    color: #111;
}

b, strong {
    font-weight: 600;
}

.marker1{
    background:linear-gradient(transparent 80%, #ff0000 0%);
}

/* カスタマイズする部分 */
.my_scroll::-webkit-scrollbar{ 
    width: 10px;
}
.my_scroll::-webkit-scrollbar-thumb{ 
    background: #00F;
    border-radius: 10px;
}
.my_scroll::-webkit-scrollbar-track-piece:start{
    background: #CCF;
}
.my_scroll::-webkit-scrollbar-track-piece:end{
    background: #DDD;
}

samp {
    display: none;
}

img {
    //animation: colorize 2s cubic-bezier(0, 0, .78, .36) 1;
    background: transparent;
    //border: 10px solid rgba(0, 0, 0, 0.12);
    //border-radius: 4px;
    display: block;
    //margin: 1.3em auto;
    max-width: 100%; 
}

.imgcenter{
    margin: 0 auto;
}
.imginline{
    display: inline;
}

.logo{
    width: 10em;
    margin-left: auto;
    margin-right: auto;
}
.index_back{
    margin-left: auto;
    margin-right: auto;
    margin-top: -2em;
}
/*斜線*/
p.strike{
    color: red;
    text-decoration: line-through;
}
/*斜線の中の文字*/
.strike span{
  color: gold;
}

@keyframes colorize {
    0% {
        -webkit-filter: grayscale(100%);
        filter: grayscale(100%);
    }
    100% {
        -webkit-filter: grayscale(0%);
        filter: grayscale(0%);
    }
}
table {
    table-layout: fixed;
}
.topcells{
    width: 46em;
    font-weight: 700;
    text-align: center;
}
.darksouko{
    
    font-weight: 700;
}
td{
    vertical-align: top;
}

.artpic{
    width: 20em;
}

.scrollArea{
	height: 60px;
	overflow: auto;
	padding-right: 20px;
    background: black;
}
/*スクロールバーの横幅指定*/
.scrollArea.deco::-webkit-scrollbar {
    width: 15px;
}
/*スクロールバーの背景色・角丸指定*/
.scrollArea.deco::-webkit-scrollbar-track {
  border-radius: 10px;
	background: #f2f2f2;
}
/*スクロールバーの色・角丸指定*/
.scrollArea.deco::-webkit-scrollbar-thumb {
  border-radius: 10px;
	background:gold;
}

.scrollAreaGames{
	height: 60px;
	overflow: auto;
    background: black;
}
/*スクロールバーの横幅指定*/
.scrollAreaGames.deco::-webkit-scrollbar {
    width: 15px;
}
/*スクロールバーの背景色・角丸指定*/
.scrollAreaGames.deco::-webkit-scrollbar-track {
  border-radius: 10px;
	background: #f2f2f2;
}
/*スクロールバーの色・角丸指定*/
.scrollAreaGames.deco::-webkit-scrollbar-thumb {
  border-radius: 10px;
	background:gold;
}

/* トップボタン */
*,
*:before,
*:after {
  -webkit-box-sizing: inherit;
  box-sizing: inherit;
}

html {
  //-webkit-box-sizing: border-box;
  box-sizing: border-box;
  font-size: 62.5%;
}

.btn,
a.btn,
button.btn {
    font-family: "Arial Black","メイリオ",sans-serif;
    font-size: 1.6rem;
    font-weight: 700;
    line-height: 1.5;
    width: 8.7em;
    position: relative;
    display: inline-block;
    padding: 1rem 4rem;
    cursor: pointer;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    -webkit-transition: all 0.3s;
    transition: all 0.3s;
    text-align: center;
    vertical-align: middle;
    text-decoration: none;
    letter-spacing: 0.1em;
    color: #212529;
    border-radius: 0.5rem;
}

a.btn-flat {
  overflow: hidden;
  padding: 1.5rem 4rem;
  color: #ff5500;
  border-radius: 0;
  background: #000;
}
a.btn-flat:hover {
    color: #111;
}

a.btn-flat span {
  position: relative;
  z-index: 1;
}

a.btn-flat:before {
  position: absolute;
  top: 0;
  left: calc(-170% + 50px);

  width: 150%;
  height: 500%;

  content: '';
  -webkit-transition: all .5s ease-in-out;
  transition: all .5s ease-in-out;
  -webkit-transform: rotate(45deg) translateX(0) translateY(0);
  transform: rotate(45deg) translateX(0) translateY(0);

  background: gold;
}

a.btn-flat:after {
  position: absolute;
  top: -400%;
  right: calc(-170% + 50px);

  width: 150%;
  height: 500%;

  content: '';
  -webkit-transition: all .5s ease-in-out;
  transition: all .5s ease-in-out;
  -webkit-transform: rotate(45deg) translateX(0) translateY(0);
  transform: rotate(45deg) translateX(0) translateY(0);

  background: gold;
}

a.btn-flat:hover:before {
  -webkit-transform: rotate(45deg) translateX(0) translateY(-50%);
  transform: rotate(45deg) translateX(0) translateY(-50%);
}

a.btn-flat:hover:after {
  -webkit-transform: rotate(45deg) translateX(0) translateY(50%);
  transform: rotate(45deg) translateX(0) translateY(50%);
}

section figure {
    margin: 0 auto;
    position: relative;
    overflow: hidden;
    //background: #000;
}
.explanation {
    color: gold;
}

.explanation figure:hover:after {
    opacity: 1;
    transform: scale(0.92, 0.88);
}
.explanation figcaption {
    position: absolute;
    width: 90%;
    top: 20%;
    left: 5%;
    right: 5%;
    text-align: left;
    margin-top: -1em;
    letter-spacing: 5px;
    opacity: 0;
    transition: all .3s ease-out .2s;
}
.explanation figure:hover figcaption {
    letter-spacing: 1px;
    opacity: 1;
}
.explanation figure img {
    transition: all .8s ease-out;
}
.explanation figure:hover img {
    opacity: .4;
    transform: scale(1.3);
}


/* 3Dボタン */

@import "https://use.fontawesome.com/releases/v5.13.0/css/all.css";


a.btn-3d-flip {
  display: block;

  width: 200px;
  margin: 0 auto;
  padding: 0;
    padding-top: 3em;

  -webkit-perspective: 600px;

  perspective: 600px;
}

a.btn-3d-flip:hover .btn-3d-flip-box {
  -webkit-transform: translateY(-50%) rotateX(90deg);
  transform: translateY(-50%) rotateX(90deg);
}

a.btn-3d-flip.btn-3d-flip2:hover .btn-3d-flip-box2 {
  -webkit-transform: translateX(-50%) rotateY(-90deg);
  transform: translateX(-50%) rotateY(-90deg);
}

.btn-3d-flip-box {
  position: relative;

  display: block;

  width: 100%;
  height: 100%;
  margin: auto;
    

  -webkit-transition: all 0.4s;

  transition: all 0.4s;
  -webkit-transform: rotateX(0);
  transform: rotateX(0);
  text-decoration: none;
  text-transform: uppercase;

  color: gold;

  -webkit-transform-style: preserve-3d;

  transform-style: preserve-3d;
}

.btn-3d-flip-box2 {
  position: relative;

  display: block;

  width: 100%;
  height: 100%;
  margin: auto;

  -webkit-transition: all 0.4s;

  transition: all 0.4s;
  -webkit-transform: rotateY(0);
  transform: rotateY(0);
  text-decoration: none;
  text-transform: uppercase;

  color: gold;

  -webkit-transform-style: preserve-3d;

  transform-style: preserve-3d;
}

.btn-3d-flip-box-face {
  display: block;
  position: relative;

  width: 100%;
  padding: 1.5rem 0;

  -webkit-transition: all 0.4s;

  transition: all 0.4s;

  color: gold;

  -webkit-backface-visibility: hidden;

  backface-visibility: hidden;
}

.btn-3d-flip-box-face--front {
  background: #eb6100;
}

.btn-3d-flip-box-face--back {
  position: absolute;
  top: 100%;
  left: 0;

  -webkit-transform: translateY(-1px) rotateX(-90deg);

  transform: translateY(-1px) rotateX(-90deg);
  -webkit-transform-origin: 50% 0;
  transform-origin: 50% 0;

  background: #dc5b00;
}

.btn-3d-flip-box-face--front2 {
  color: #000;
  border: 2px solid #000;
  background: gold;
}

.btn-3d-flip-box-face--back2 {
  position: absolute;
  top: 0;
  left: 100%;

  -webkit-transform: translateX(-1px) rotateY(90deg);

  transform: translateX(-1px) rotateY(90deg);
  -webkit-transform-origin: 0 0;
  transform-origin: 0 0;

  color: gold;
  border: 2px solid #000;
  background: #000;
}

.fa-position-right {
  position: absolute;
  top: calc(50% - 0.5em);
  right: 1rem;
}

/* 戻るボタン */

.btn-emergency {
  font-size: 1.6rem;
  font-weight: 700;
  line-height: 1.5;
  position: relative;
  display: inline-block;
  padding: 1rem 4rem;
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
  -webkit-transition: all 0.3s;
  transition: all 0.3s;
  text-align: center;
  vertical-align: middle;
  text-decoration: none;
  letter-spacing: 0.1em;
  color: #212529;
  border-radius: 0.5rem;
}

a.btn-emergency {
  position: relative;

  display: block;

  width: 200px;
  height: 130px;
  margin: 0 auto;
}

a.btn-emergency:hover .btn-emergency-top {
  top: 10px;

  height: 50px;
}

a.btn-emergency:active .btn-emergency-top {
  top: 20px;

  height: 40px;
}

.btn-emergency-top {
  position: absolute;
  top: 0;
  left: 20px;

  width: 160px;
  height: 60px;
  margin-top: 30px;

  -webkit-transition: all 0.3s;

  transition: all 0.3s;

  border-radius: 0 0 50% 50%;
  background: #300;
}

.btn-emergency-top:before {
  position: absolute;
  top: -30px;
  left: 0;

  width: 160px;
  height: 60px;

  content: "";

  border-radius: 80px / 30px;
  background: #600;
}

.btn-emergency-top span {
  font-size: 20px;
  font-weight: bold;

  position: absolute;
  top: -12px;
  left: 0;

  width: 100%;

  -webkit-transform: scaleY(0.75);

  transform: scaleY(0.75);
  text-align: center;

  color: #f6a3a3;
}

.btn-emergency-bottom {
  position: absolute;
  top: 38px;
  left: 0;

  width: 200px;
  height: 80px;

  border-radius: 100px / 40px;
  background: #f55;
  -webkit-box-shadow: 0 8px 0 #c00;
  box-shadow: 0 8px 0 #c00;
}

/* 付箋リストデザイン　*/
ul {
  padding: 0;
}
ol {
  counter-reset:number; /*数字をリセット*/
  list-style-type: none!important; /*数字を一旦消す*/
  padding:0;
}

ul li, ol li {
    width: inherit;
    color: gold;
    border-left: solid 6px #f00;/*左側の線*/
    border-bottom: solid 2px #999;/*下に灰色線*/
    background: #000;
    margin-bottom: 5px;/*下のバーとの余白*/
    padding: 0.5em;
    list-style-type: none!important;/*ポチ消す*/
    font-weight: bold;
}

ul.common,
ol.common{
    width: max-content;
    line-height: 1;
}

ul span.gyakuni{
    color: turquoise;
}
ul.heytoc{
    width:16em;
    margin: 0 auto;
    line-height: 0.5;
}
ul.dlgame{
    width: max-content;
    margin-left: auto;
}

img.heytoc{
    width: 50%;
    padding: 2em;
}
img.heypic{
    height: 2.5em;
}

/*ダウンロードボタン*/
@import "https://use.fontawesome.com/releases/v5.13.0/css/all.css";

*,
*:before,
*:after {
  -webkit-box-sizing: inherit;
  box-sizing: inherit;
}

html {
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  font-size: 62.5%;
}

a.btn-3d-circle {
    
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
  -webkit-transition: all 0.3s;
  transition: all 0.3s;
  text-align: center;
  vertical-align: middle;
  text-decoration: none;
  letter-spacing: 0.1em;
  color: #000;
  border-radius: 0.5rem;
    
  display: block;

  width: 100px;
  height: 100px;
  margin-left: auto;
  padding: 0;

  border-radius: 50%;
}
.dltxt{
    font-size: 1.2rem;
  font-weight: 700;
    font-style: oblique;
  line-height: 1.5;
    padding-bottom: 0.3em;
  position: relative;
  display: inline-block;
    transform : scale(1, 2.5);   /* 変形 横,縦 */
    text-shadow: 0px 1px 1px khaki;
}

.btn-3d-circle-content {
  display: block;
  line-height: 100px;

  width: 100px;
  height: 100px;

  -webkit-transition: all 0.6s;

  transition: all 0.6s;

  border-radius: 50%;
  background: #ff5500;
  background: -webkit-gradient(
    linear,
    left top,
    left bottom,
    from(#ff5500),
    color-stop(37%, gold),
    to(#ff2200)
  );
  background: -webkit-linear-gradient(
    top,
    #f2f5f6 0%,
    #e3eaed 37%,
    #c8d7dc 100%
  );
  background: linear-gradient(to bottom, maroon 0%, khaki 37%, maroon 100%);

  -webkit-transform-style: preserve-3d;

  transform-style: preserve-3d;
  -webkit-perspective: 150px;
  perspective: 150px;
}

.btn-3d-circle:hover .btn-3d-circle-content {
  -webkit-transform: rotateY(0.5turn) rotateX(-0.03turn);
  transform: rotateY(0.5turn) rotateX(-0.03turn);
}

.btn-3d-circle:hover .btn-3d-circle-front {
  opacity: 0;
}

.btn-3d-circle:hover .btn-3d-circle-back {
  top: calc(50% - 2rem);
  left: calc(50% - 0.75rem);

  opacity: 1;
}

.btn-3d-circle-back {
  font-size: 3rem;

  position: absolute;
  top: 70%;
  left: 70%;

  -webkit-transition: all 0.3s;

  transition: all 0.3s;
  letter-spacing: 0;

  opacity: 0;
}

/*裏話　斜めボタン*/
a.btn-gradient.readme{
    font-size: 1.2em;
    width: 8em;
    padding: 0;
  -webkit-transform: skew(-15deg);
  transform: skew(-15deg);
  color: #222;
  border-radius: 0;
  background-image: -webkit-gradient(linear, left top, right top, from(maroon), to(khaki));
  background-image: -webkit-linear-gradient(left, maroon 0%, khaki 100%);
  background-image: linear-gradient(90deg, maroon 0%, khaki 100%);
  -webkit-box-shadow: 0 5px 10px rgba(0, 0, 0, .1);
  box-shadow: 0 5px 10px rgba(0, 0, 0, .1);
}
a.btn-gradient.insidestory{
    width: 15em;
  -webkit-transform: skew(-15deg);
  transform: skew(-15deg);
  color: #fff;
  border-radius: 0;
  background-image: -webkit-gradient(linear, left top, right top, from(#000), to(aqua));
  background-image: -webkit-linear-gradient(left, #000 0%, aqua 100%);
  background-image: linear-gradient(90deg, #000 0%, aqua 100%);
  -webkit-box-shadow: 0 5px 10px rgba(0, 0, 0, .1);
  box-shadow: 0 5px 10px rgba(0, 0, 0, .1);
}


a.btn-gradient:hover {
  -webkit-transform: skew(0);
  transform: skew(0);
  //color: #fff;
  -webkit-box-shadow: 0 2px 3px rgba(0, 0, 0, .1);
  box-shadow: 0 2px 3px rgba(0, 0, 0, .1);
}

.heyblock{
    background: #000;
    margin-left: 5em;
    margin-right: 5em;
    padding:1em;
}
.heyblock img{
    width: 50%;
    margin:1em;
}

/*twiter 埋め込み　カスタマイズ*/
p.twitter-timeline{
    text-align: center;
}

/*トップ３画像白くするエフェクト*/
.img_wrap{
  //margin: 0 auto;
  overflow: hidden;
}
.img_wrap img{
  width: 100%;
  cursor: pointer;
  transition-duration: 0.3s;
}
.img_wrap:hover img{
  opacity: 0.6;
  transition-duration: 0.3s;
}

.topgrid {
    display: grid;      /* グリッドコンテナを作る */
    grid-template-columns: 1fr 1fr 1fr 1fr;     /* 縦向きのグリッドラインを決める */
    grid-template-rows: 1fr 1fr;            /* 横向きのグリッドラインを決める */
   
}
.topgrid-child {
}
.topgrid-child:nth-child(1) {
   grid-column: 1/3;               /* 配置指定 */
    grid-row: 1/3;                  /* 配置指定 */
}
.topgrid-child:nth-child(2) {
    grid-column:3/4;                /* 配置指定 */
    grid-row: 1/2;                  /* 配置指定 */
}
.topgrid-child:nth-child(3) {
    grid-column: 4/5;               /* 配置指定 */
    grid-row: 1/2;                  /* 配置指定 */
}
.topgrid-child:nth-child(4) {
    grid-column: 3/4;               /* 配置指定 */
    grid-row: 2/3;                  /* 配置指定 */
}
.topgrid-child:nth-child(5) {
    grid-column: 4/5;               /* 配置指定 */
    grid-row: 2/3;                   /* 配置指定 */
}

/* 全体のスタイル */
.swiper-wrapper {
	width: 100%;
	height: 250px;
}
/* 全スライド共通スタイル */
.swiper-slide {
	color: #ffffff;
	width: 100%;
	height: 100%;
	text-align: center;
	line-height: 250px;
}

/*スライド*/
/* 4の倍数＋1枚目のスライドのスタイル（1枚目、5枚目…） */
.swiper-slide:nth-child(4n+1) {
	background-color: #EECB27;
}
/* 4の倍数＋2枚目のスライドのスタイル（2枚目、6枚目…） */
.swiper-slide:nth-child(4n+2) {
	background-color: #E13239;
}
/* 4の倍数＋3枚目のスライドのスタイル（3枚目、7枚目…） */
.swiper-slide:nth-child(4n+3) {
	background-color: #1F1762;
}
/* 4の倍数＋4枚目のスライドのスタイル（4枚目、8枚目…） */
.swiper-slide:nth-child(4n+4) {
	background-color: #BEDAE5;
}