:root {
    --background-color: #2c3e50;
    --second--background-color: #bdc3c7;
    --danger--background-color: #c0392b;

    --accent-color: #ecf0f1;
}
* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
body {
    background: var(--background-color);
}
.container {
    background: var(--second--background-color);
    border-radius: 12px;
    box-shadow: 15px 30px 35px rgba(0,0,0,0.8);
    width: 500px;
    height: 100vh;
    padding: 40px;
    margin: 100px auto;
}
#coin {
    position: relative;
    margin: auto;
    width: 350px;
    height: 350px;
    transform-style: preserve-3d;
}
#coin img {
    width: 100%;
}
.head,
.tail {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left:0;
    backface-visibility: hidden;
}
.tail {
    transform: rotateX(180deg);
}
.roll_to_head {
    animation: heads-spin 2s ease-out;
}
.roll_to_tail {
    animation: tails-spin 2s ease-out;
}
@keyframes tails-spin {
    0% {
        transform: rotateX(0);
    }
    100% {
        transform: rotateX(1980deg); /* 1980+180= 2160 deg */
    }
}
@keyframes heads-spin {
    0% {
        transform: rotateX(0);
    }
    100% {
        transform: rotateX(2160deg);
    }
}
.result {
  display: flex;
  align-content: center;
  justify-content: center;
  font-weight: 500px;
  padding: 20px;
  margin-top: 100px;
}
.result span:nth-last-child(1){
    margin-left: 50%;
}
.buttons {
    display: flex;
    justify-content: space-evenly;
    align-items: center;
    margin-block: 150px;
}
button {
    cursor: pointer;
    box-shadow: rgba(0, 0, 0, 0.35) 0px 5px 15px;
}
.start-btn {
    background: var(--background-color);
    color: var(--accent-color); 
} 
.reset-btn,
.start-btn {
    padding-block: 12px;
    padding-inline: 32px;
    border-radius: 6px;
}
.reset-btn {
    background: var(--danger--background-color);
    color: var(--accent-color); 
}
.start-btn:disabled {
    background: #bdc3c7;
    color: inherit;
}