:root {
  --content-width: 50%;
}

/* base styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: inherit;
}

html {
  font-size: 62.5%;
  font-weight: 300;
  font-family: nyt-imperial,georgia,'times new roman',times,serif;
}

body {
  font-size: 1.25rem;
  position: relative;
}

p {
  font-size: 2rem;
  line-height: 1.6;
  margin-bottom: 0.9375rem;
  margin-top: 0;
  color: #333;
}

.btn-default,
.btn-default:link,
.btn-default:visited {
  font-size: 1.1rem;
  color: white;
  padding: 1rem 1.2rem;
  background-color: #6288a5;
  border-radius: 5px;
  font-weight: bold;
  cursor: pointer;
  outline: none;
  transition: all .4s;
}

.btn-default:hover,
.btn-default:active  {
  background-color: #326891;
}

.wide-img {
  width: 100%;
  height: auto;
}

.wide-img-70{
  width: 70%;
  height: auto;
  left:50%;
  transform: translateX(20%);
}

img {
  width: 100%;
  height: auto;
}

/* Navigation */
.nav {
  height: 5.5rem;
  border-bottom: 1px solid #d3d3d3;
  position: sticky;
  top: 0;
  width: 100%;
  background-color: white;
  z-index: 10000;
}

.nav::after {
  display: inline-block;
  width: 0;
  height: 0;
  clear: both;
}

.nav__list {
  list-style: none;
  text-align: center;
  padding: 1rem 2rem;
}

.nav__left ul {
  float: left;
  position: absolute;
  top:50%;
  transform: translateY(-50%);
}

.nav__left ul > * {
  margin-right: 2rem;
}

.nav__left i {
  color: black;
  font-size: 1.5rem;
}

.link--black:link, 
.link--black:visited {
  color: black;
  font-size: 1.5rem;
  font-weight: bold;
  text-decoration: none;
  letter-spacing: 1px;
}

.link--black:hover, 
.link--black:active {
  text-decoration: underline
}

.nav__right {
  position: absolute;
  right: 2rem;
  top:50%;
  transform: translateY(-50%);
}

.nav__list li {
  display: inline
}

.logo {
  display: inline-block;
  width: 20rem;
  position: absolute;
  top:50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
   

/* header */
header {
  text-align: center;
}

header h1 {
  margin-left: 40rem;
  margin-top: 4rem;
  font-size: 3.5rem;
  font-weight: bold;
  width: 36%;
  line-height: 1.4;
  text-align: left;
  margin-bottom: 3rem;
}

header img {
  width: 100%;
}

header p,
header span {
  font-size: 1.6rem;
  width: 100%;
  text-align: left;
  margin: 0 auto;
  line-height: 1.2;
  color: #666;
}

header span {
  color: #888;
  font-size: 1.4rem
}

/* article about */
.article__about {
  width: var(--content-width);
  margin: 4rem auto;
}

.article__about > p {
  font-size: 1.7rem;
  line-height: 1.25rem;
  font-weight: bold;
}

.article__about p > a:link,
.article__about p > a:visited {
  color: black;
  text-decoration: none;
  border-bottom: 1px solid #888;
  transition: all .2s;
}

.article__about p > a:hover,
.article__about p > a:active {
  border-bottom: 1px solid white;
}

.article__about__details {
  display: flex;
  align-items: center;
  justify-content: space-between
}

.article__about__details ul {
  list-style: none;
}

.article__about__details li {
  display: inline-block;
  margin-left: 1.5rem;
} 

/* article content */
.article--center {
  text-align: left;
  width: 50%;
  transform: translateX(50%); 
}

.article__content a:link,
.article__content a:visited {
  color: #326891;
}

.article__content a:hover,
.article__content a:active {
  color: #326891;
  text-decoration: none;
}

/* article login */
.article__login {
  text-align: center;
}

.article__login hr {
  width: 10%;
  margin: 0 auto;
  color: #666;
  margin: 2rem auto;
}

.article__login p {
  font-size: 1.3rem;
  font-weight: bold;
  margin-bottom: 0;
}

.article__login a:link,
.article__login a:visited {
  color: #326891;
  text-decoration: none;
  font-size: 1.3rem;
  font-weight: bold;
}

/* Section Theory*/

.section__theory {
  width: 75%;
  margin: 3rem auto;
}

.section__theory h2 {
  font-size: 1.7rem;
  font-weight: bold;
  padding-bottom: 0.5rem;
  margin-left: 5rem;
}

.section__theory > p {
  color: #666;
  margin-left: 5rem;
}

.section__theory p {
  font-size: 1.2rem;
  line-height: 1.4;
}

.theory__container {
  width: 120rem;
  margin-left: 5rem;
}

.theory__image {
  float: left;
  width: 25rem;
}

.theory__image p{
  margin-top: -15rem;
  word-spacing: 0.5rem;
  width: 95%;
}

.theory__image > img{
  width: 25rem;
}

.theory__author {
  clear: both;
  content: ".";
  display: table;
  margin-top: 5rem;
  padding-top: 3rem;
  margin-left: 5rem;
} 

.theory__author hr{
  margin-bottom: 1.5rem;
  width: 5rem;
}

.theory__author p{
  font-size: 1.4rem;
}

/* youtube */
.youtube__container {
  text-align: center;
  margin: 4rem 0; 
}

.youtube__container iframe {
  width: 70rem;
  height: 40rem;
}

.youtube__container p{
  margin-top: 5px;
  line-height: 1.4;
  font-size: 1.7rem;
  color: #666;
  text-align: left;
  margin-left: 3rem;
}

.youtube__container span{
  font-size: 1.3rem;
}


/* section telescope */
.section__telescope {
  width: 50%;
  margin: 4rem auto;
}

.section__telescope img {
  width: 100%;
   text-align: center;
 }
 
 .section__telescope p {
  margin-top: 5px;
  line-height: 1.4;
  font-size: 1.3rem;
  color: #666;
}

/* article footer */
.article-footer {
  width: var(--content-width);
  margin: 3rem auto;
}

.article-footer p,
.article-footer a  {
  font-size: 1.2rem;
  color: #666;
  text-decoration: none;
}  

.article-footer a:hover,
.article-footer a:active {
  text-decoration: underline;
}

.article-footer__content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin: 3rem 0;
}


.article-footer__content button {
  width: 50%;
  font-size: 1.4rem;
  font-weight: bold;
}


.article-footer__content ul {
  list-style: none;
}

.article-footer__content li {
  display: inline;
  margin-left: 2rem;
}


/* MORE SECTION */

.section__related {
  display: flex;
  margin: 3rem 8rem;
}

.section__left {
  flex: 3;
  margin-top: 3rem;
}

.section__left hr {
  width: 97%;
  height: 1px;
  background-color: black;
}

.section__related img {
  width: 30rem;
}


.section__more h3 {
  font-size: 1.5rem;
  font-weight: bold;
  margin-top: 2rem;
}

.section__more a {
  text-decoration: none;
  color: black;
}

.section__more > div {
  display: flex;
  flex-wrap: wrap;
}

.article__box {
  width: 30rem;
  margin-right: 1.8rem;
  margin-top: 2rem;
}

.article__box figcaption {
  text-align: right;
  font-size: 1.1rem;
  color: rgb(153, 153, 153);
  margin-top: 0.5rem;
}

.article__box a {
  font-weight: bold;
  font-size: 1.5rem;
  text-decoration: none;
  color: black;
}

.article__box h4 {
  margin: 0.4rem 0;
  line-height: 1.5;
}

.article__box a:hover {
  color: rgb(153, 153, 153);
}

.article__box p {
  color: rgb(153, 153, 153);
  font-size: 1.2rem;
}

/* section right */

.section__right {
  flex: 1;
  margin-top: 3rem;
}

.section__right hr {
  width: 100%;
  height: 1px;
  background-color: black;
}

.section__right h3 {
  font-size: 1.5rem;
  font-weight: bold;
  margin-top: 2rem;
  margin-bottom: 2rem;
}

.section__right--list {
  list-style: none;
  
}

.section__right--list > li {
  padding: 2rem;
  border-top: 1px solid rgb(226, 226, 226);
}

.section__right--list a {
  text-decoration: none;
  font-size: 1.8rem;
  color: black;
  font-weight: 400;  
}

/* Footer */

.footer {
  border-top: 1px solid rgb(226, 226, 226);
  margin: 5rem 8rem 0 8rem;
  position: relative;
}

.footer__logo {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-content: center;
  padding: 1.5rem 0;
}

.footer__logo img{
  width: 20rem;
}

.footer__logo a:last-of-type {
  align-self: flex-end;
  text-decoration: none;
  color: rgb(98, 136, 165);

}

.footer__main {
  display: flex;
  justify-content: space-between;
}

.footer__main h5{
  margin-top: 3rem;
  margin-bottom: 1.5rem;
  font-size: 1.3rem;
  color: rgb(51, 51, 51);
}

.footer__main ul {
  font-size: 1.3rem;
  list-style: none;
}

.footer__main li {
  margin-bottom: 1rem;
}

.footer__main a {
  text-decoration: none;
  color: black;

}

.footer__main a:hover{
  text-decoration: underline;
}

.footer__subscribe {
  border-left: 1px solid rgb(226, 226, 226);
  padding-left: 2rem;

}

.subscribe {
  margin-bottom: 1.5rem !important;
  font-size: 1.6rem;

}

.subscribe i {
  margin-right: 0.5rem;
  width: 2rem;
}

.subscribe hr {
  color: #eee;
}


/* footer secondary */
.footer__secondary {
  list-style: none;
  display: flex;
  justify-content: center;
  padding-top: 2rem;
  margin: 2rem 0;
  margin-bottom: 6rem;
  border-top: 1px solid rgb(226, 226, 226);
}

.footer__secondary li {
  margin: 0 5px;
}

.footer__secondary a:link,
.footer__secondary a:visited {
  text-decoration: none;
  color: rgb(146, 146, 146);
}

.footer__secondary a:hover,
.footer__secondary a:active {
  text-decoration: underline;
}

/* footer fixed */
.footer__fixed {
  display: flex;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  text-align: center;
  justify-content: center;
  border-top: 1px solid black;
  background-color: white;
}

.footer__fixed a {
  padding: 1rem 0;
  align-self: center;
  font-size: 1.5rem;
  text-decoration: none;
  color: black;
}

/* social icons */

.social__list .social__icons:link,
.social__list .social__icons:visited {
  display: block;
  height: 1.8rem;
  width: 1.8rem;
  border-radius: 50%;
  padding: 5px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  background-color: #eee;
  border: 1px solid white;
  color: black;
  transition: all .3s;
}


.social__list  .social__icons:hover,
.social__list  .social__icons:active {
  background-color: white;
  border: 1px solid rgb(167, 167, 167);
}


.social__list {
  display: flex;
}