*,
*::before,
*::after {
  box-sizing: border-box;
}

* {
  margin: 0;
}

html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
  overflow: hidden;
  font-family: "Gill Sans", sans-serif;
  background-color: #f7fbff;
}

body {
  position: relative;
}

.background-overlay {
  width: 100%;
  height: 100%;
  background-image: url("background.jpg");
  background-size: cover;
  background-position: center;
  opacity: 0.1;
  z-index: -1;
}

h1 {
  margin-bottom: 20px;
  font-size: 64px;
}

.header-info {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.question-board {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  gap: 1em;
  flex-direction: column;
  justify-content: center;
  align-items: stretch;
  width: 80%;
  max-width: 900px;
  padding: 20px;
  border-radius: 15px;
  overflow-y: hidden;
}

#leader-board {
  display: none;
  max-height: 250px;
  overflow-y: auto;
}

#question-title {
  display: flex;
  gap: 5px;
  font-size: 20px;
  margin-bottom: 10px;
  align-items: center;
}

#question-category {
  background-color: green;
  color: white;
  border-radius: 10px;
  padding: 5px;
  font-size: 14px;
  display: none;
}

.status-bar {
  display: flex;
  gap: 20px;
  padding: 10px 0;
  border-top: 1px solid #aaa;
  border-bottom: 1px solid #aaa;
  justify-content: space-between;
}

.option {
  cursor: pointer;
  background-color: #626975;
  min-height: 40px;
  line-height: 40px;
  padding-left: 20px;
  border-radius: 5px;
  color: white;
  border: 1px solid #636974;
  flex-shrink: 1;
  flex-grow: 1;
}

#options-container {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.option:hover {
  transform: scale(1.02);
  transition: all 0.5;
  background-color: #f8fbff;
  color: #636974;
}

#question {
  user-select: none;
}

#operation-bar {
  margin-top: 10px;
  display: flex;
  gap: 5px;
}

#start-button {
  display: block;
  background-color: #000;
  color: #f8fbff;
}

button {
  border: none;
  padding: 10px;
  background-color: #f8fbff;
  border: 1px solid #aaa;
  border-radius: 5px;
  color: #636974;
  cursor: pointer;
}

button:hover {
  background-color: #636974;
  color: white;
}

button:disabled {
  border: 1px solid gainsboro;
  color: gainsboro;
}

button:disabled:hover {
  cursor: not-allowed;
  color: gainsboro;
  background-color: #f8fbff;
}

#start-button:hover {
  opacity: 80%;
}

.timer {
  display: flex;
  justify-content: center;
  align-items: center;
  background: 237, 248, 255;
  border: 1px solid #aaa;
  width: 80px;
  height: 80px;
  margin: 0 15px;
  border-radius: 50%;
  font-size: 20px;
  transform: all 0.5s;
}

header {
  display: flex;
  gap: 10px;
  justify-content: space-between;
}

#choose-next-difficulty {
  display: flex;
  gap: 5px;
}

#next-difficulty-choser {
  gap: 10px;
  display: none;
}

#next-btns {
  margin-top: 10px;
  display: flex;
  gap: 4px;
}

#next-btns button {
  padding: 4px;
}