/**
 * Secure PDF Flipbook Reader — Animation Design System
 * 
 * Hardware-accelerated keyframe layouts for loaders, pulse, and warning screens.
 */

/* 1. Shimmering Skeleton Loader Effect */
.loading-skeleton {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #f1f5f9;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

/* Base styling for dark-mode loading placeholders */
.idle-placeholder {
    background-color: #1e293b;
    opacity: 0.8;
}

.skeleton-shimmer {
    position: absolute;
    top: 0;
    left: -150%;
    width: 150%;
    height: 100%;
    background: linear-gradient(
        to right,
        rgba(255, 255, 255, 0) 0%,
        rgba(255, 255, 255, 0.45) 50%,
        rgba(255, 255, 255, 0) 100%
    );
    animation: shimmer 1.8s infinite;
    z-index: 1;
}

/* Dark mode shimmer adjustments */
.idle-placeholder .skeleton-shimmer {
    background: linear-gradient(
        to right,
        rgba(255, 255, 255, 0) 0%,
        rgba(255, 255, 255, 0.08) 50%,
        rgba(255, 255, 255, 0) 100%
    );
}

.skeleton-icon {
    font-size: 2.5rem;
    z-index: 2;
    opacity: 0.35;
    animation: bounceSlow 2.5s infinite ease-in-out;
}

/* Keyframes */
@keyframes shimmer {
    0% {
        left: -150%;
    }
    50% {
        left: 100%;
    }
    100% {
        left: 100%;
    }
}

@keyframes bounceSlow {
    0%, 100% {
        transform: translateY(0) scale(1.0);
    }
    50% {
        transform: translateY(-8px) scale(1.05);
    }
}

/* 2. Main App Loader Ring Spinner */
#app-loader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: #090d16;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 999;
    opacity: 1;
    transition: opacity 0.5s ease;
}

#app-loader.fade-out {
    opacity: 0;
    pointer-events: none;
}

.loader-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

/* Classic CSS Ring Spinner */
.spinner-ring {
    display: inline-block;
    position: relative;
    width: 80px;
    height: 80px;
    margin-bottom: 1.5rem;
}

.spinner-ring div {
    box-sizing: border-box;
    display: block;
    position: absolute;
    width: 64px;
    height: 64px;
    margin: 8px;
    border: 5px solid var(--accent-color);
    border-radius: 50%;
    animation: spinnerRotate 1.2s cubic-bezier(0.5, 0, 0.5, 1) infinite;
    border-color: var(--accent-color) transparent transparent transparent;
}

.spinner-ring div:nth-child(1) {
    animation-delay: -0.45s;
}
.spinner-ring div:nth-child(2) {
    animation-delay: -0.3s;
}
.spinner-ring div:nth-child(3) {
    animation-delay: -0.15s;
}

@keyframes spinnerRotate {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.loader-message {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: 0.5px;
    color: var(--text-primary);
}

.loader-subtext {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Loader Retry Button */
.btn-retry {
    margin-top: 1.5rem;
    padding: 0.6rem 1.25rem;
    background-color: var(--accent-color);
    border: none;
    border-radius: 6px;
    color: var(--text-primary);
    font-weight: bold;
    cursor: pointer;
    box-shadow: 0 4px 10px rgba(217, 119, 6, 0.4);
    transition: all 0.25s ease;
}

.btn-retry:hover {
    background-color: var(--accent-hover);
    box-shadow: 0 4px 15px rgba(217, 119, 6, 0.6);
}

/* 3. Security Pulse Alert & Fading */
@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
        box-shadow: 0 0 0 0 rgba(217, 119, 6, 0.4);
    }
    50% {
        transform: scale(1.08);
        opacity: 0.9;
        box-shadow: 0 0 0 15px rgba(217, 119, 6, 0);
    }
}

.overlay-icon {
    display: inline-block;
    animation: alertPulse 2s infinite cubic-bezier(0.4, 0, 0.6, 1);
}

@keyframes alertPulse {
    0%, 100% {
        transform: scale(1);
        text-shadow: 0 0 5px rgba(217, 119, 6, 0.5);
    }
    50% {
        transform: scale(1.15);
        text-shadow: 0 0 20px rgba(217, 119, 6, 0.9);
    }
}

/* Fade In Screen overlay transitions */
.security-overlay {
    animation: overlayFadeIn 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes overlayFadeIn {
    from {
        opacity: 0;
        backdrop-filter: blur(0px);
    }
    to {
        opacity: 1;
        backdrop-filter: blur(10px);
    }
}

/* 4. Page ambient hover glow */
#book-container::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: calc(100% + 40px);
    height: calc(100% + 40px);
    background: radial-gradient(circle, rgba(217, 119, 6, 0.05) 0%, rgba(0, 0, 0, 0) 70%);
    pointer-events: none;
    z-index: 1;
    border-radius: 50%;
    opacity: 0.8;
}