@import url("https://fonts.googleapis.com/css2?family=Ubuntu&display=swap");
* {
  box-sizing: border-box;
}
body {
  font-family: "Ubuntu", sans-serif;
  margin: 0;
}
.container {
  background-size: cover;
  background-repeat: no-repeat;
  background-position: center;
  width: 100%;
  padding-bottom: 10px;
}
.container.main {
  background-image: url(../images/geometry-gfb45467ab_1920.jpg);
}
.container.math {
  background-image: url(../images/math-work-4711302_1920.jpg);
}
.container.biology {
  background-image: url(../images/bacteria-ge8bcddb27_1920.jpg);
}
.container.socialstudies {
  background-image: url(../images/compass-g8e372dd80_1920.jpg);
}
.container.computerscience {
  background-image: url(../images/source-g5e03fa362_1920.jpg);
}
h1 {
  font-size: 4.5rem;
  color: red;
  margin-bottom: 0;
}
.header {
  text-align: center;
  background-color: #fff;
  padding: 20px 0;
  margin-top: 80px;
}
nav {
  position: fixed;
  background-color: #222;
  top: 0;
  left: 0;
  right: 0;
}
nav ul {
  list-style-type: none;
}
nav ul li a {
  color: #fff;
  text-decoration: none;
  padding: 7px 15px;
  transition: all 0.3s ease-in-out;
  cursor: pointer;
}
nav a:hover,
nav a:active {
  color: red;
}

.options {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  border: 2px solid red;
  border-radius: 4px;
  width: 70%;
  margin: 5% auto;
  max-width: 1000px;
}
.subject {
  background-color: #fff;
  width: 70%;
  height: 40%;
  border: 2px solid #555;
  border-radius: 4px;
  margin: 30px;
  text-align: center;
  padding: 20px;
  height: 150px;
  letter-spacing: 1px;
  color: #555;
}
.subject h2 {
  text-shadow: 1px 1px 1px white, 2px 1px 2px red;
  color: #333;
  font-weight: bold;
  font-size: 20px;
  letter-spacing: 2px;
}
.btn {
  padding: 7px 10px;
  background-color: rgb(141, 138, 138);
  border-radius: 5px;
  color: #fff;
  font-size: 18px;
  cursor: pointer;
  letter-spacing: 1px;
}
.btn:hover,
#btn_card:hover {
  background-color: red;
  color: #fff;
  transform: scale(0.9);
  border: 1px red solid;
}
.btn a {
  text-decoration: none;
  color: #fff;
}
footer {
  text-align: center;
  color: #fff;
  background-color: #222;
  padding: 15px 0;
}
footer a {
  text-decoration: none;
  color: #fff;
}
footer a:hover {
  color: red;
}
#questions {
  flex-direction: column;
  width: 95%;
}
.count h2 {
  background-color: red;
  color: #fff;
  font-size: 2rem;
  padding: 20px;
  text-align: center;
  border-radius: 4px;
}
.card {
  background-color: #fff;
  border-radius: 5px;
  width: 90%;
  height: 50%;
  max-width: 600px;
  padding: 10px;
  overflow-y: scroll;
}
.card h3 {
  text-align: center;
}
.card ul {
  list-style-type: none;
  padding: 0;
}
.card ul li {
  font-size: 1.2rem;
  margin: 1rem 0;
}
.card ul li label {
  cursor: pointer;
}
#btn_card {
  background-color: rgb(141, 138, 138);
  color: #fff;
  display: block;
  cursor: pointer;
  font-size: 1.1rem;
  font-family: inherit;
  padding: 7px 10px;
  margin-top: 15px;
  letter-spacing: 1px;
}
#btn_card.hide {
  display: none;
}
#card.card button {
  padding: 10px;
  border-radius: 8px;
  background-color: red;
  color: #fff;
  cursor: pointer;
  margin-top: 40px;
  font-size: 18px;
}

@media screen and (min-width: 400px) and (max-width: 860px) {
}
@media screen and (min-width: 860px) {
  body {
    height: 100vh;
  }
  .header {
    margin-top: 30px;
  }
  nav ul {
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .subject {
    width: 40%;
    height: 25%;
    font-size: 0.8em;
  }
  .container {
    height: 100%;
  }
  .options {
    height: 60%;
  }
}