/*
 * Globals
 */

/* Links */
a,
a:focus,
a:hover {
  color: #fff;
}

/* Custom default button */
.btn-secondary,
.btn-secondary:hover,
.btn-secondary:focus {
  color: #041e61;
  text-shadow: none; /* Prevent inheritance from `body` */
  background-color: #fff;
  border: .05rem solid #fff;
}


/*
 * Base structure
 */

html,
body {
  height: 100%;
  background-color: #041e61;
}

body {
  display: -ms-flexbox;
  display: flex;
  color: #fff;
  text-shadow: 0 .05rem .1rem rgba(0, 0, 0, .5);
  box-shadow: inset 0 0 5rem rgba(0, 0, 0, .5);
}

.cover-container {
  max-width: 42em;
}


/*
 * Header
 */
.masthead {
  margin-bottom: 2rem;
}

.masthead-brand {
  margin-bottom: 0;
}

.nav-masthead .nav-link {
  padding: .25rem 0;
  font-weight: 700;
  color: rgba(255, 255, 255, .5);
  background-color: transparent;
  border-bottom: .25rem solid transparent;
}

.nav-masthead .nav-link:hover,
.nav-masthead .nav-link:focus {
  border-bottom-color: rgba(255, 255, 255, .25);
}

.nav-masthead .nav-link + .nav-link {
  margin-left: 1rem;
}

.nav-masthead .active {
  color: #fff;
  border-bottom-color: #fff;
}

@media (min-width: 48em) {
  .masthead-brand {
    float: left;
  }
  .nav-masthead {
    float: right;
  }
}


/*
 * Cover
 */
.cover {
  padding: 0 1.5rem;
}
.cover .btn-lg {
  padding: .75rem 1.25rem;
  font-weight: 700;
}

/*
 * Loading
 */

:root {
    --hue: 223;
    --bg: hsl(var(--hue),10%,90%);
    --fg: hsl(var(--hue),10%,10%);
    --primary: hsl(var(--hue),90%,55%);
    --primary-l: hsl(var(--hue),90%,65%);
    --primary-d: hsl(var(--hue),90%,45%);
    --white: hsl(var(--hue),10%,100%);
    --white-d: hsl(var(--hue),10%,45%);
    font-size: calc(16px + (24 - 16) * (100vw - 320px) / (1280 - 320));
}

.book,
.book__pg-shadow,
.book__pg {
    animation: cover 7s ease-in-out infinite;
}
.book {
    background-color: var(--primary-l);
    border-radius: 0.25em;
    box-shadow:
        0 0.25em 0.5em hsla(0,0%,0%,0.3),
        0 0 0 0.25em var(--primary) inset;
    padding: 0.25em;
    perspective: 37.5em;
    position: relative;
    margin-left: 25%;
    width: 50%;
    height: 6em;
    transform: translate3d(0,0,0);
    transform-style: preserve-3d;
}
.book__pg-shadow,
.book__pg {
    position: absolute;
    left: 0.25em;
    width: calc(50% - 0.25em);
}
.book__pg-shadow {
    animation-name: shadow;
    background-image: linear-gradient(-45deg,hsla(0,0%,0%,0) 50%,hsla(0,0%,0%,0.3) 50%);
    filter: blur(0.25em);
    top: calc(100% - 0.25em);
    height: 3.75em;
    transform: scaleY(0);
    transform-origin: 100% 0%;
}
.book__pg {
    animation-name: pg1;
    background-color: var(--white);
    background-image: linear-gradient(90deg,hsla(var(--hue),10%,90%,0) 87.5%,hsl(var(--hue),10%,90%));
    height: calc(100% - 0.5em);
    transform-origin: 100% 50%;
}
.book__pg--2,
.book__pg--3,
.book__pg--4 {
    background-image:
        repeating-linear-gradient(hsl(var(--hue),10%,10%) 0 0.125em,hsla(var(--hue),10%,10%,0) 0.125em 0.5em),
        linear-gradient(90deg,hsla(var(--hue),10%,90%,0) 87.5%,hsl(var(--hue),10%,90%));
    background-repeat: no-repeat;
    background-position: center;
    background-size: 2.5em 4.125em, 100% 100%;
}
.book__pg--2 {
    animation-name: pg2;
}
.book__pg--3 {
    animation-name: pg3;
}
.book__pg--4 {
    animation-name: pg4;
}
.book__pg--5 {
    animation-name: pg5;
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
    :root {
        --bg: hsl(var(--hue),10%,30%);
        --fg: hsl(var(--hue),10%,90%);
    }
}

/* Animations */
@keyframes cover {
    from, 5%, 45%, 55%, 95%, to {
        animation-timing-function: ease-out;
        background-color: var(--primary-l);
    }
    10%, 40%, 60%, 90% {
        animation-timing-function: ease-in;
        background-color: var(--primary-d);
    }
}
@keyframes shadow {
    from, 10.01%, 20.01%, 30.01%, 40.01% {
        animation-timing-function: ease-in;
        transform: translate3d(0,0,1px) scaleY(0) rotateY(0);
    }
    5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, 95% {
        animation-timing-function: ease-out;
        transform: translate3d(0,0,1px) scaleY(0.2) rotateY(90deg);
    }
    10%, 20%, 30%, 40%, 50%, to {
        animation-timing-function: ease-out;
        transform: translate3d(0,0,1px) scaleY(0) rotateY(180deg);
    }
    50.01%, 60.01%, 70.01%, 80.01%, 90.01% {
        animation-timing-function: ease-in;
        transform: translate3d(0,0,1px) scaleY(0) rotateY(180deg);
    }
    60%, 70%, 80%, 90%, to {
        animation-timing-function: ease-out;
        transform: translate3d(0,0,1px) scaleY(0) rotateY(0);
    }
}
@keyframes pg1 {
    from, to {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.4deg);
    }
    10%, 15% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(180deg);
    }
    20%, 80% {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(180deg);
    }
    85%, 90% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(180deg);
    }
}
@keyframes pg2 {
    from, to {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(0.3deg);
    }
    5%, 10% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.3deg);
    }
    20%, 25% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.9deg);
    }
    30%, 70% {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(179.9deg);
    }
    75%, 80% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.9deg);
    }
    90%, 95% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.3deg);
    }
}
@keyframes pg3 {
    from, 10%, 90%, to {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(0.2deg);
    }
    15%, 20% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.2deg);
    }
    30%, 35% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.8deg);
    }
    40%, 60% {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(179.8deg);
    }
    65%, 70% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.8deg);
    }
    80%, 85% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.2deg);
    }
}
@keyframes pg4 {
    from, 20%, 80%, to {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(0.1deg);
    }
    25%, 30% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.1deg);
    }
    40%, 45% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.7deg);
    }
    50% {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(179.7deg);
    }
    55%, 60% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.7deg);
    }
    70%, 75% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0.1deg);
    }
}
@keyframes pg5 {
    from, 30%, 70%, to {
        animation-timing-function: ease-in;
        background-color: var(--white-d);
        transform: translate3d(0,0,1px) rotateY(0);
    }
    35%, 40% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0deg);
    }
    50% {
        animation-timing-function: ease-in-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(179.6deg);
    }
    60%, 65% {
        animation-timing-function: ease-out;
        background-color: var(--white);
        transform: translate3d(0,0,1px) rotateY(0);
    }
}

/*
 * Footer
 */
.mastfoot {
  color: rgba(255, 255, 255, .5);
}