/* overall coding */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  background: skyblue;
  overflow-x: hidden;
  height: 100vh;
}
/* start of navigation */
nav {
  background: hsl(208, 81%, 41%);
}
#logo_image {
  max-width: 50%;
  max-height: 10vmax;
  border: 2px solid hsl(224, 100%, 62%);
  border-radius: 50%;
  animation: logo_border_change 4s linear infinite;
}
#logo_image:hover {
  animation-iteration-count: 0;
  border: 1px solid white;
}
@keyframes logo_border_change {
  0% {
    border-top-color: hsl(197, 71%, 73%);
  }
  25% {
    border-top-color: hsl(224, 100%, 62%);
    border-right-color: hsl(197, 71%, 73%);
  }
  50% {
    border-right-color: hsl(224, 100%, 62%);
    border-bottom-color: hsl(197, 71%, 73%);
  }
  75% {
    border-bottom-color: hsl(224, 100%, 62%);
    border-left-color: hsl(197, 71%, 73%);
  }
  100% {
    border-left-color: hsl(224, 100%, 62%);
    border-top-color: hsl(197, 71%, 73%);
  }
}
.nav_tabs {
  font-size: larger;
  border-radius: 50%;
}
.nav_tabs:hover {
  animation: nav_tabs_hover 0.2s linear 1;
  animation-fill-mode: forwards;
  font-weight: bolder;
}

/* end of navigation */
/* start of introductory preview   */

.carousel {
  margin: auto;
}
.carousel_images {
  height: 60vh;
}

@media (max-width: 991px) {
  .carousel_images {
    height: 30vh;
  }
}

/* end of introductory preview  */

/* start of website introduction */

.intro_title {
  text-decoration: underline;
  font-weight: bold;
  text-align: center;
}
.important_intro_text {
  font-weight: bold;
  font-size: xx-large;
  text-align: center;
}
.intro_text {
  line-height: 1.4em;
  font-size: x-large;
  text-align: justify;
}
.intro_image {
  max-width: 50%;
  margin-left: 25%;
  margin-right: 23%;
}
/* end of website introduction */

/* start of footer section */

footer {
  background: hsl(215, 55%, 21%);
  color: white;
}

.feedback_text {
  font-size: x-large;
  font-weight: 700;
  margin-top: 4rem;
  text-align: center;
}
.social_media_div {
  position: relative;
}
.social_media_text {
  margin-left: 3.8rem;
  font-size: x-large;
  font-weight: bolder;
  margin-top: 1rem;
}
.social_media_icons {
  border-bottom: 3px solid black;
}
.bi-youtube {
  color: red;
}
.social_media_icons:hover {
  color: black;
  transition: 0.3s;
}
.copyright_text {
  text-align: center;
  font-size: 2rem;
  font-weight: bolder;
  border-top: 3px solid white;
}
.feedback_text:hover,
.social_media_text:hover,
.copyright_text:hover {
  color: hsl(226, 87%, 57%);
  transition: 0.3s;
}
@media (max-width: 991px) {
  .feedback_text {
    font-size: larger;
    text-align: center;
  }
  .feedback_input {
    margin-left: 3%;
    width: 95%;
  }
}
@media (max-width: 767px) {
  .feedback_div {
    border-bottom: 3px solid white;
  }
  .social_media_div {
    margin-left: 25%;
    margin-bottom: 1rem;
  }
  .social_media_icons {
    margin-right: 1rem;
  }
}
/* end of footer section */

/* ------------------------------------ */
/* about_creators_page */
/* ------------------------------------ */
.about_creators_heading {
  text-align: center;
  border-bottom: 3px solid black;
  overflow: hidden;
}
.quote {
  font-family: "Patrick Hand", cursive;
  font-size: x-large;
  color: black;
  text-align: justify;
  text-indent: 7%;
}
.creators_names_headings {
  text-align: center;
  overflow: hidden;
}
.main_list_about_tpz,
.main_list_about_hman,
.main_list_about_mhh {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}
.lists_about_creators {
  font-family: "Times New Roman", Times, serif;
  text-align: center;
  margin-left: 10%;
}
.tpz,
.hman {
  border-left: 2px solid black;
}
.mhh_image {
  margin-left: 12%;
}

@media (max-width: 1119px) {
  .tpz {
    border-bottom: 2px solid black;
  }
  .hman .creators_names_headings {
    margin-left: 20%;
  }
}

/* ------------------------------------ */
/* improving_learning_page */
/* ------------------------------------ */

.improving_learning_intro_div {
  display: flex;
}
.tips_images {
  width: 70%;
  margin-left: 15%;
}
.improving_learning_intro_heading {
  text-align: center;
}
.intro_img {
  margin-left: 10%;
}
.intro_text {
  font-size: xx-large;
  line-height: 1.3em;
  align-self: center;
}
.intro_text a {
  text-decoration: none;
}
.intro_text a:hover {
  color: black;
}
.improving_learning_intro_heading {
  text-decoration: underline;
  text-underline-offset: 7px;
}

@media (max-width: 991px) {
  .intro_img {
    margin-left: 15%;
  }
}
@media (max-width: 767px) {
  .intro_img {
    margin: auto;
  }
}

.four_skills_heading,
.reading_tips_headings,
.writing_tips_headings,
.listening_tips_headings,
.speaking_tips_headings {
  text-decoration: underline;
  text-decoration-style: dashed;
  text-underline-offset: 4px;
  text-align: center;
}
.reading_tips_text,
.writing_tips_text,
.listening_tips_text,
.speaking_tips_text,
.additional_advice_text {
  font-size: x-large;
  font-weight: 500;
  text-align: center;
}
.additional_advice_heading {
  text-align: center;
  border: 3px solid black;
}
.good_luck_text {
  font-size: 5em;
  font-weight: 900;
  text-align: center;
  border-top: 3px solid black;
}