:root {
    /* Color Palette - Light Blue Academic / Apple Style */
    --bg-gradient-start: #e0eafc;
    --bg-gradient-mid: #cfdef3;
    --bg-gradient-end: #f5f7fa;

    /* Liquid Glass Effects */
    --glass-bg: rgba(255, 255, 255, 0.6);
    --glass-border: rgba(255, 255, 255, 0.8);
    --glass-shadow: 0 12px 40px rgba(31, 38, 135, 0.12);
    --glass-highlight: inset 0 1px 0 rgba(255, 255, 255, 1);

    /* Typography */
    --text-main: #1d1d1f;
    --text-secondary: #424245;
    --text-muted: #86868b;
    --accent-color: #0071e3;
    --accent-light: #e8f4fd;

    /* Presentation */
    --slide-transition: 0.8s cubic-bezier(0.25, 1, 0.5, 1);
}

body {
    margin: 0;
    padding: 0;
    font-family:
        -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto,
        Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji",
        "Segoe UI Symbol";
    background: radial-gradient(
        circle at 0% 0%,
        var(--bg-gradient-start) 0%,
        var(--bg-gradient-mid) 50%,
        var(--bg-gradient-end) 100%
    );
    background-attachment: fixed;
    color: var(--text-main);
    overflow: hidden;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Glass Panel Base */
.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border: 1px solid var(--glass-border);
    border-radius: 30px;
    box-shadow: var(--glass-shadow), var(--glass-highlight);
}

/* Slides Framework */
#presentation-container {
    width: 100vw;
    height: 100vh;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.slide {
    position: absolute;
    /* Expanded slide dimensions: Much wider horizontally */
    width: 97vw;
    max-width: 1750px;
    height: 94vh;
    max-height: 980px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(40px) scale(0.95);
    transition:
        opacity var(--slide-transition),
        transform var(--slide-transition),
        visibility var(--slide-transition);
    display: flex;
    flex-direction: column;
    padding: 45px 70px;
    box-sizing: border-box;
    z-index: 1;
}

.slide.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
    z-index: 10;
}

.slide.prev {
    transform: translateY(-40px) scale(0.95);
}

/* Typography & Content */
.slide-header {
    margin-bottom: 25px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    padding-bottom: 15px;
    flex-shrink: 0;
}

.slide-title {
    font-size: 2.8rem;
    font-weight: 700;
    letter-spacing: -0.015em;
    color: var(--text-main);
    margin: 0;
    background: linear-gradient(135deg, #1d1d1f 0%, #434350 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.slide-subtitle {
    font-size: 1.3rem;
    color: var(--accent-color);
    font-weight: 500;
    margin: 8px 0 0 0;
}

.slide-body {
    flex: 1;
    display: flex;
    gap: 40px;
    align-items: center;
    overflow-y: auto;
    scrollbar-width: thin;
    scrollbar-color: rgba(0, 0, 0, 0.15) transparent;
}

.slide-body::-webkit-scrollbar {
    width: 8px;
}
.slide-body::-webkit-scrollbar-thumb {
    background-color: rgba(0, 0, 0, 0.15);
    border-radius: 10px;
}

/* Fixed col-1 layout: Aligns items vertically but keeps inner text left-aligned */
.slide-body.col-1 {
    flex-direction: column;
    justify-content: flex-start;
    align-items: center; /* Center the containers */
    text-align: left; /* Keep text flowing left naturally */
}

.slide-body.col-1 .text-content {
    width: 100%;
    margin: 0 auto;
}

.title-slide .slide-body.col-1 {
    justify-content: center;
    align-items: center;
    text-align: center;
}

.text-content {
    flex: 1;
    font-size: 1.4rem;
    color: var(--text-secondary);
    font-weight: 400;
    line-height: 1.6;
}

/* Card-style Elegant Lists */
.text-content ul {
    list-style: none;
    padding-left: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.text-content li {
    background: rgba(255, 255, 255, 0.5);
    border: 1px solid rgba(255, 255, 255, 0.8);
    padding: 16px 24px 16px 52px;
    border-radius: 16px;
    box-shadow: 0 4px 20px rgba(31, 38, 135, 0.03);
    position: relative;
    transition:
        transform 0.3s cubic-bezier(0.25, 1, 0.5, 1),
        background 0.3s ease,
        box-shadow 0.3s ease;
}

.text-content li:hover {
    background: rgba(255, 255, 255, 0.85);
    transform: translateX(6px);
    box-shadow: 0 8px 25px rgba(31, 38, 135, 0.08);
}

.text-content li::before {
    content: "";
    position: absolute;
    left: 24px;
    top: 26px;
    width: 10px;
    height: 10px;
    background: linear-gradient(135deg, var(--accent-color), #00c6ff);
    border-radius: 50%;
    box-shadow: 0 2px 6px rgba(0, 113, 227, 0.4);
}

.text-content li strong {
    color: var(--text-main);
    font-weight: 700;
}

/* Nested lists styling */
.text-content li ul {
    margin-top: 14px;
    gap: 10px;
}

.text-content li ul li {
    background: rgba(255, 255, 255, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.4);
    padding: 12px 20px 12px 45px;
    border-radius: 12px;
    box-shadow: inset 0 0 10px rgba(255, 255, 255, 0.2);
}

.text-content li ul li::before {
    left: 20px;
    top: 22px;
    width: 8px;
    height: 8px;
    background: var(--text-muted);
    box-shadow: none;
}

.text-content li ul li:hover {
    transform: translateX(4px);
    background: rgba(255, 255, 255, 0.6);
}

/* Math Equations Optimization */
code {
    font-family: "Cambria Math", "Latin Modern Math", "Georgia", serif;
    font-size: 1.15em;
    background: rgba(0, 113, 227, 0.08);
    color: var(--accent-color);
    padding: 3px 8px;
    border-radius: 8px;
    font-style: italic;
    border: 1px solid rgba(0, 113, 227, 0.15);
    white-space: nowrap;
}

.media-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 100%;
}

.media-content img {
    max-width: 100%;
    max-height: 450px;
    object-fit: contain;

    /* Perfect 4-corner border radius */
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.9);
    box-shadow: 0 12px 36px rgba(0, 0, 0, 0.08);

    /* Hover effects for images */
    transition:
        transform 0.3s cubic-bezier(0.25, 1, 0.5, 1),
        box-shadow 0.3s ease;
    cursor: zoom-in;
}

.media-content img:hover {
    transform: scale(1.04);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
}

/* Layout overrides for Slide 3 (Why NKF) */
#slide-3 .slide-body {
    flex-direction: column;
}
#slide-3 .media-content {
    width: 100%;
}
#slide-3 .media-content img {
    max-height: 380px;
}

/* Specific optimization for Slide 4 Figure */
#slide-4 .slide-body {
    gap: 15px; /* Reduce gap between image and table */
}

#slide-4 .media-content {
    width: 100%;
    align-items: center;
    justify-content: center;
    margin-top: 0;
    order: -1; /* Move image above table */
}

#slide-4 .media-content img {
    width: 80%; /* Shrink by 10% from previous 90% */
    max-width: 80%;
    max-height: 360px; /* Adjust height to prevent overflow */
    margin: 0 auto;
    display: block;
}

#slide-4 .media-content img:hover {
    transform: scale(0.96); /* Adjusted hover scale */
}

/* Image Lightbox / Zoom-in Mode */
#lightbox {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(255, 255, 255, 0.4);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 9999;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.4s ease;
}

#lightbox.active {
    opacity: 1;
    pointer-events: auto;
    cursor: zoom-out;
}

#lightbox img {
    max-width: 90vw;
    max-height: 90vh;
    border-radius: 24px;
    box-shadow: 0 25px 80px rgba(0, 0, 0, 0.15);
    background: #fff;
    object-fit: contain;
    transform: scale(0.9);
    transition: transform 0.4s cubic-bezier(0.25, 1, 0.5, 1);
}

#lightbox.active img {
    transform: scale(1);
}

.media-caption {
    margin-top: 15px;
    font-size: 1.1rem;
    color: var(--text-muted);
    text-align: center;
}

/* Title Slide Optimization */
.title-slide {
    justify-content: center;
    align-items: center;
    text-align: center;
    background: linear-gradient(
        135deg,
        rgba(255, 255, 255, 0.7) 0%,
        rgba(255, 255, 255, 0.3) 100%
    );
}

.title-slide .slide-title {
    font-size: 4.2rem;
    margin-bottom: 25px;
    line-height: 1.2;
}

.title-slide .authors {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 35px;
    font-weight: 500;
}

.core-question {
    max-width: 950px;
    margin: 0 auto;
    padding: 35px 40px;
    background: rgba(255, 255, 255, 0.55);
    border-radius: 24px;
    border: 1px solid rgba(255, 255, 255, 0.9);
    box-shadow: 0 12px 40px rgba(31, 38, 135, 0.08);
    font-size: 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
    text-align: center;
}

.presenter-info {
    margin-top: 60px;
    padding-top: 30px;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
    display: flex;
    flex-direction: column;
    gap: 12px;
    align-items: center;
}

.presenter-info .name {
    font-size: 1.6rem;
    font-weight: 600;
    color: var(--accent-color);
    letter-spacing: 0.02em;
}

.presenter-info .date {
    font-size: 1.2rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* Paper Stack Widget for Title Slide */
.paper-stack {
    position: relative;
    width: 280px;
    height: 380px;
    margin: 10px auto 40px auto;
    perspective: 1000px;
}

.paper-stack img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: top;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(31, 38, 135, 0.15);
    border: 1px solid rgba(255, 255, 255, 0.9);
    transition:
        transform 0.5s cubic-bezier(0.25, 1, 0.5, 1),
        box-shadow 0.5s ease;
    background: #fff;
    cursor: pointer;
}

.paper-stack img:nth-child(1) {
    transform: rotate(-6deg) translateX(-30px) translateY(10px)
        translateZ(-40px);
    z-index: 1;
}

.paper-stack img:nth-child(2) {
    transform: rotate(4deg) translateX(20px) translateY(-5px) translateZ(-20px);
    z-index: 2;
}

.paper-stack img:nth-child(3) {
    transform: rotate(-2deg) translateX(0) translateY(0) translateZ(0);
    z-index: 3;
}

.paper-stack:hover img:nth-child(1) {
    transform: rotate(-12deg) translateX(-50px) translateY(20px)
        translateZ(-20px);
}

.paper-stack:hover img:nth-child(2) {
    transform: rotate(8deg) translateX(40px) translateY(-10px) translateZ(-10px);
}

.paper-stack:hover img:nth-child(3) {
    transform: rotate(0deg) translateX(0) translateY(-15px) translateZ(10px);
    box-shadow: 0 20px 40px rgba(31, 38, 135, 0.25);
}

/* Custom Diagram Elements */
.flow-diagram {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    width: 100%;
}

.flow-node {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    padding: 18px 35px;
    border-radius: 16px;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.06);
    font-weight: 500;
    font-size: 1.2rem;
    color: var(--text-main);
    width: 80%;
    text-align: center;
    backdrop-filter: blur(10px);
}

.flow-node.highlight {
    background: var(--accent-light);
    border-color: var(--accent-color);
    color: var(--accent-color);
    font-weight: 600;
}

.flow-arrow {
    color: var(--accent-color);
    font-size: 2rem;
}

/* Comparison Table Styling */
.glass-table {
    width: 100%;
    max-width: 1500px;
    margin: 0 auto 20px auto;
    border-collapse: separate;
    border-spacing: 0;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.06);
    border: 1px solid var(--glass-border);
    flex-shrink: 0;
}

.glass-table th,
.glass-table td {
    padding: 14px 22px;
    text-align: left;
    background: rgba(255, 255, 255, 0.4);
    border-bottom: 1px solid rgba(255, 255, 255, 0.5);
    font-size: 1.15rem;
}

.glass-table th {
    background: rgba(255, 255, 255, 0.7);
    font-weight: 600;
    color: var(--text-main);
    font-size: 1.25rem;
}

.glass-table tr:last-child td {
    border-bottom: none;
}

/* Controls & UI */
.controls-container {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 20px;
    z-index: 100;
    padding: 12px 24px;
    border-radius: 40px;
}

.control-btn {
    background: rgba(255, 255, 255, 0.6);
    border: 1px solid var(--glass-border);
    color: var(--text-main);
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.4rem;
    cursor: pointer;
    transition: all 0.2s ease;
    backdrop-filter: blur(12px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.control-btn:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.95);
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.12);
    color: var(--accent-color);
}

.control-btn:disabled {
    opacity: 0.3;
    cursor: default;
}

.slide-counter {
    display: flex;
    align-items: center;
    font-weight: 500;
    color: var(--text-secondary);
    font-size: 1.2rem;
    padding: 0 15px;
}

.progress-bar-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 6px;
    background: rgba(0, 0, 0, 0.05);
    z-index: 100;
}

.progress-bar {
    height: 100%;
    background: var(--accent-color);
    width: 0%;
    transition: width 0.4s cubic-bezier(0.25, 1, 0.5, 1);
}

@keyframes bgDrift {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

/* Conclusion Slide Grid Layout */
#slide-9 .text-content {
    max-width: 1400px !important;
}

#slide-9 .text-content > ul {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin-bottom: 20px;
}

#slide-9 .text-content > ul > li {
    margin-bottom: 0;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    padding: 26px 30px 26px 60px;
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.65);
}

#slide-9 .text-content > ul > li::before {
    top: 32px; /* Align dot with the title */
    left: 28px;
    width: 12px;
    height: 12px;
}

#slide-9 .text-content > ul > li > strong {
    font-size: 1.15em;
    margin-bottom: 10px;
    display: block;
    color: var(--text-main);
    line-height: 1.3;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    padding-bottom: 10px;
}