html,
body {
    margin: 0;
    padding: 0;
    height: 100%;
    overflow: hidden;
}

.fullscreen {
    width: 100%;
    height: 100%;
    position: relative;
    background: black;
}

.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0;
    /* only use transition for fade mode, animation classes will override for flip/slide */
    transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1);
    will-change: transform, opacity;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    contain: strict;
}

.slide.visible {
    opacity: 1;
}

/* disable opacity transition for animated slides (flip/slide use their own keyframes) */
.slide.animate-next,
.slide.animate-prev,
.slide.enter-next,
.slide.enter-prev,
.slide.slide-out-next,
.slide.slide-out-prev,
.slide.slide-in-next,
.slide.slide-in-prev {
    transition: none;
}

/* page-turn flip animation */
.fullscreen {
    perspective: 2000px;
    transform-style: preserve-3d;
}

@keyframes flipOutNext {
    0% {
        transform: rotateY(0deg);
        opacity: 1;
    }

    100% {
        transform: rotateY(-90deg);
        opacity: 0;
    }
}

@keyframes flipInNext {
    0% {
        transform: rotateY(90deg);
        opacity: 0;
    }

    30% {
        opacity: 1;
    }

    100% {
        transform: rotateY(0deg);
        opacity: 1;
    }
}

@keyframes flipOutPrev {
    0% {
        transform: rotateY(0deg);
        opacity: 1;
    }

    100% {
        transform: rotateY(90deg);
        opacity: 0;
    }
}

@keyframes flipInPrev {
    0% {
        transform: rotateY(-90deg);
        opacity: 0;
    }

    30% {
        opacity: 1;
    }

    100% {
        transform: rotateY(0deg);
        opacity: 1;
    }
}

.slide.animate-next {
    animation: flipOutNext 0.5s cubic-bezier(0.4, 0, 1, 1) forwards;
    transform-origin: left center;
    opacity: 1;
}

.slide.animate-prev {
    animation: flipOutPrev 0.5s cubic-bezier(0.4, 0, 1, 1) forwards;
    transform-origin: right center;
    opacity: 1;
}

.slide.enter-next {
    animation: flipInNext 0.5s cubic-bezier(0, 0, 0.2, 1) forwards;
    transform-origin: right center;
    opacity: 0;
}

.slide.enter-prev {
    animation: flipInPrev 0.5s cubic-bezier(0, 0, 0.2, 1) forwards;
    transform-origin: left center;
    opacity: 0;
}

/* Slide animation - uses translateX with GPU-composited transform */
@keyframes slideOutNext {
    0% {
        transform: translateX(0);
        opacity: 1;
    }

    100% {
        transform: translateX(-100%);
        opacity: 0.3;
    }
}

@keyframes slideInNext {
    0% {
        transform: translateX(100%);
        opacity: 0.3;
    }

    100% {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes slideOutPrev {
    0% {
        transform: translateX(0);
        opacity: 1;
    }

    100% {
        transform: translateX(100%);
        opacity: 0.3;
    }
}

@keyframes slideInPrev {
    0% {
        transform: translateX(-100%);
        opacity: 0.3;
    }

    100% {
        transform: translateX(0);
        opacity: 1;
    }
}

.slide.slide-out-next {
    animation: slideOutNext 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    opacity: 1;
}

.slide.slide-in-next {
    animation: slideInNext 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    opacity: 0;
}

.slide.slide-out-prev {
    animation: slideOutPrev 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    opacity: 1;
}

.slide.slide-in-prev {
    animation: slideInPrev 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    opacity: 0;
}

/* hint overlay */
.hint {
    position: absolute;
    bottom: 10%;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.6);
    color: white;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 1.2rem;
    opacity: 0;
    transition: opacity 0.5s;
}

.hint.visible {
    opacity: 1;
}

/* Circular Timer style */
.timer-container {
    position: fixed;
    top: 20px;
    left: 20px;
    width: 30px;
    height: 30px;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 10000;
    pointer-events: auto;
    cursor: pointer;
    opacity: 0.5;
    transition: opacity 0.3s;
}

.timer-container:hover {
    opacity: 1;
}

.timer-svg {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.timer-bg {
    fill: none;
    stroke: rgba(255, 255, 255, 0.2);
    stroke-width: 8;
}

.timer-progress {
    fill: none;
    stroke: white;
    stroke-width: 8;
    stroke-linecap: round;
    stroke-dasharray: 283;
    /* 2 * PI * r (45) approx 282.7 */
    stroke-dashoffset: 0;
    transition: stroke-dashoffset 1s linear, opacity 0.3s;
}

.timer-text {
    position: absolute;
    color: white;
    font-size: 0.7rem;
    font-weight: bold;
    font-family: Arial, sans-serif;
    text-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

/* Key Modal */
.key-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 20000;
}

.key-modal-content {
    background: white;
    padding: 40px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: #333;
}

.key-modal-content h2 {
    margin-top: 0;
    color: #1a73e8;
}

.key-modal-content input {
    padding: 12px;
    font-size: 1.5rem;
    margin: 20px 0;
    width: 200px;
    text-align: center;
    letter-spacing: 4px;
    border: 2px solid #ccc;
    border-radius: 8px;
    text-transform: uppercase;
}

.key-modal-content input:focus {
    border-color: #1a73e8;
    outline: none;
}

.key-modal-content button {
    background: #1a73e8;
    color: white;
    border: none;
    padding: 12px 30px;
    font-size: 1.1rem;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    transition: background 0.3s;
}

.key-modal-content button:hover {
    background: #1557b0;
}