/* ==========================================================================
   FLIPKART-STYLE ULTRA-FAST SKELETON LOADING & TRANSITIONS
   Theme: Crisp Flipkart Neutral Slate Base (#eef0f3) with Gleaming
          High-Speed White & Warm Brand Orange Glow Shimmer
   ========================================================================== */

/* Top Flipkart / YouTube Brand-Orange Progress Bar */
.spa-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 3.5px;
    width: 0%;
    background: linear-gradient(90deg, #ff7b5a 0%, #ff5532 50%, #ff3b11 100%);
    box-shadow: 0 0 12px rgba(255, 85, 50, 0.8), 0 0 5px rgba(255, 85, 50, 0.5);
    z-index: 9999999;
    pointer-events: none;
    transition: width 0.28s cubic-bezier(0.1, 0.9, 0.2, 1), opacity 0.2s ease;
    opacity: 0;
}

.spa-progress-bar.active {
    opacity: 1;
}

/* SPA Page Container Transitions */
.spa-page-container {
    min-height: 70vh;
    transition: opacity 0.25s ease, transform 0.25s ease;
}

.spa-page-container.spa-loading {
    opacity: 0.95;
}

/* ==========================================================================
   FLIPKART SIGNATURE SHIMMER ANIMATION (Ultra-Smooth 60fps GPU Accelerated)
   ========================================================================== */
@keyframes flipkartShimmer {
    0% {
        background-position: -250% 0;
    }
    100% {
        background-position: 250% 0;
    }
}

.sk-shimmer,
.sk-box,
.sk-circle,
.sk-line,
.sk-pill,
.sk-banner,
.sk-avatar,
.sk-btn,
.sk-thumb,
.sk-fk-search,
.sk-fk-cat-icon,
.sk-fk-cat-label,
.sk-fk-card-thumb,
.sk-fk-rating-badge,
.sk-fk-price-tag,
.sk-fk-card-btn,
.nc-img-skeleton::before {
    background: linear-gradient(
        90deg,
        #eef0f3 0%,
        #eef0f3 20%,
        #fbfcfd 35%,
        #ffffff 50%,
        #fff4f0 58%,
        #fbfcfd 65%,
        #eef0f3 80%,
        #eef0f3 100%
    ) !important;
    background-size: 250% 100% !important;
    animation: flipkartShimmer 1.15s cubic-bezier(0.4, 0, 0.2, 1) infinite !important;
    border-radius: 6px;
    will-change: background-position;
    transform: translateZ(0);
}

/* ==========================================================================
   FULL-PAGE SKELETON PRELOADER (Flipkart Instant Dismiss Architecture)
   ========================================================================== */
#nc-skeleton-preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: #ffffff;
    z-index: 999998;
    overflow-y: auto;
    overflow-x: hidden;
    transition: opacity 0.22s ease-out, visibility 0.22s ease-out;
    opacity: 1;
    visibility: visible;
}

#nc-skeleton-preloader.sk-hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

/* Skeleton Layout Container */
.sk-page-layout {
    max-width: 1240px;
    margin: 0 auto;
    padding: 16px 20px 60px;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    gap: 32px;
    background: #ffffff;
}

/* 1. Header Skeleton */
.sk-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    padding: 12px 0 20px;
    border-bottom: 1px solid #eef0f3;
}

.sk-header-logo {
    width: 155px;
    height: 40px;
    border-radius: 6px;
    flex-shrink: 0;
}

.sk-fk-search {
    flex: 1;
    max-width: 440px;
    height: 38px;
    border-radius: 20px;
}

.sk-header-nav {
    display: flex;
    gap: 18px;
}

.sk-header-nav .sk-pill {
    width: 80px;
    height: 22px;
    border-radius: 16px;
}

.sk-header-btn {
    width: 110px;
    height: 38px;
    border-radius: 20px;
    flex-shrink: 0;
}

@media (max-width: 920px) {
    .sk-fk-search,
    .sk-header-nav {
        display: none;
    }
}

/* 2. Flipkart Signature Category Pills Bar */
.sk-fk-categories {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    padding: 14px 18px;
    background: #ffffff;
    border: 1px solid #eef0f3;
    border-radius: 12px;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.03);
    overflow-x: auto;
}

.sk-fk-cat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    flex: 1;
    min-width: 68px;
}

.sk-fk-cat-icon {
    width: 46px;
    height: 46px;
    border-radius: 50% !important;
}

.sk-fk-cat-label {
    width: 54px;
    height: 12px;
    border-radius: 4px;
}

/* 3. Hero Section Skeleton */
.sk-hero-grid {
    display: grid;
    grid-template-columns: 1.15fr 0.85fr;
    gap: 36px;
    align-items: center;
    background: #fbfcfd;
    border: 1px solid #eef0f3;
    border-radius: 14px;
    padding: 28px 24px;
}

@media (max-width: 992px) {
    .sk-hero-grid {
        grid-template-columns: 1fr;
    }
}

.sk-hero-copy {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.sk-eyebrow {
    width: 160px;
    height: 24px;
    border-radius: 16px;
}

.sk-title-line-1 {
    width: 90%;
    height: 42px;
    border-radius: 8px;
}

.sk-title-line-2 {
    width: 72%;
    height: 42px;
    border-radius: 8px;
}

.sk-sub-1 {
    width: 100%;
    height: 16px;
    margin-top: 4px;
}

.sk-sub-2 {
    width: 85%;
    height: 16px;
}

/* Dual Action Buttons in ONE LINE */
.sk-cta-row {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-top: 10px;
    flex-wrap: nowrap;
}

.sk-cta-btn-primary {
    width: 145px;
    height: 40px;
    border-radius: 8px;
    flex-shrink: 0;
}

.sk-cta-btn-ghost {
    width: 175px;
    height: 40px;
    border-radius: 8px;
    flex-shrink: 0;
}

.sk-avatar-proof {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-top: 6px;
}

.sk-avatar-stack {
    display: flex;
}

.sk-avatar-stack .sk-circle {
    width: 38px;
    height: 38px;
    border-radius: 50% !important;
    margin-right: -10px;
    border: 2px solid #ffffff;
}

.sk-proof-text {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

/* Hero Right: Browser Mockup Skeleton */
.sk-browser-mock {
    background: #ffffff;
    border: 1px solid #eef0f3;
    border-radius: 14px;
    padding: 18px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.03);
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.sk-browser-dots {
    display: flex;
    gap: 6px;
    margin-bottom: 2px;
}

.sk-browser-dots .sk-circle {
    width: 10px;
    height: 10px;
    border-radius: 50% !important;
}

.sk-browser-banner {
    width: 100%;
    height: 190px;
    border-radius: 10px;
}

.sk-browser-kicker {
    width: 100px;
    height: 18px;
    border-radius: 8px;
}

.sk-browser-heading {
    width: 80%;
    height: 22px;
    border-radius: 6px;
}

.sk-browser-tags {
    display: flex;
    gap: 10px;
    margin-top: 4px;
}

.sk-browser-tag {
    width: 110px;
    height: 24px;
    border-radius: 12px;
}

/* 4. Flipkart-Style Stats / Trust Bar */
.sk-stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    padding: 20px 24px;
    background: #ffffff;
    border: 1px solid #eef0f3;
    border-radius: 12px;
    box-shadow: 0 1px 4px rgba(0,0,0,0.02);
}

@media (max-width: 768px) {
    .sk-stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.sk-stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 8px;
}

.sk-stat-num {
    width: 55px;
    height: 32px;
    border-radius: 6px;
}

.sk-stat-label {
    width: 90px;
    height: 14px;
    border-radius: 4px;
}

/* 5. Section Heading Skeleton */
.sk-section-header {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    text-align: center;
    margin-top: 6px;
}

.sk-section-badge {
    width: 120px;
    height: 22px;
    border-radius: 14px;
}

.sk-section-title {
    width: 48%;
    max-width: 420px;
    height: 34px;
    border-radius: 8px;
}

.sk-section-desc {
    width: 62%;
    max-width: 560px;
    height: 16px;
    border-radius: 4px;
}

/* 6. Flipkart Signature 4-Card Course / Product Grid */
.sk-fk-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}

@media (max-width: 1024px) {
    .sk-fk-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 580px) {
    .sk-fk-grid {
        grid-template-columns: 1fr;
    }
}

.sk-fk-card {
    background: #ffffff;
    border: 1px solid #eef0f3;
    border-radius: 10px;
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.03);
    transition: transform 0.2s ease;
}

.sk-fk-card-thumb {
    width: 100%;
    height: 160px;
    border-radius: 8px;
}

.sk-fk-rating-badge {
    width: 48px;
    height: 20px;
    border-radius: 4px;
}

.sk-fk-card-title {
    width: 82%;
    height: 18px;
    border-radius: 4px;
}

.sk-fk-card-subtitle {
    width: 60%;
    height: 14px;
    border-radius: 4px;
}

.sk-fk-card-price-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: auto;
    padding-top: 10px;
    border-top: 1px solid #f1f3f6;
}

.sk-fk-price-tag {
    width: 75px;
    height: 20px;
    border-radius: 4px;
}

.sk-fk-card-btn {
    width: 85px;
    height: 32px;
    border-radius: 6px;
}

/* 7. Content & Syllabus Detail Lines Skeleton */
.sk-content-block {
    background: #ffffff;
    border: 1px solid #eef0f3;
    border-radius: 12px;
    padding: 24px 20px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

/* ==========================================================================
   IMAGE SKELETON LAZY LOADING
   ========================================================================== */
img.nc-lazy {
    opacity: 0;
    transition: opacity 0.3s ease, filter 0.3s ease;
    filter: blur(4px);
}

img.nc-lazy.nc-loaded {
    opacity: 1;
    filter: blur(0);
}

.nc-img-skeleton {
    position: relative;
    overflow: hidden;
    background: #f1f3f6;
}

.nc-img-skeleton::before {
    content: "";
    position: absolute;
    inset: 0;
    z-index: 1;
    transition: opacity 0.25s ease;
}

.nc-img-skeleton.loaded::before {
    opacity: 0;
    pointer-events: none;
}