@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;500;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Google+Sans+Text:wght@400;500;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;600&display=swap');

:root {
    --bg-light: #F8F9FA;
    --card-bg: #FFFFFF;
    --text-main: #202124;
    --text-muted: #5F6368;
    
    /* Google Brand Colors */
    --g-blue: #4285F4;
    --g-red: #EA4335;
    --g-yellow: #FBBC05;
    --g-green: #34A853;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    /* Prefer Google Sans if available, otherwise fallback to Google Sans Text from webfont, then Roboto */
    font-family: 'Google Sans', 'Google Sans Text', 'Product Sans', Roboto, Arial, sans-serif;
    background-color: var(--bg-light);
    color: var(--text-main);
    height: 100vh;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

.presentation-container {
    position: relative;
    width: 100vw;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Controls */
.controls {
    position: absolute;
    bottom: 40px;
    z-index: 100;
    display: flex;
    align-items: center;
    gap: 20px;
    background: var(--card-bg);
    padding: 12px 24px;
    border-radius: 50px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.nav-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    cursor: pointer;
    transition: all 0.2s;
}
.nav-btn:hover:not(:disabled) { 
    color: var(--g-blue); 
    transform: scale(1.1); 
}
.nav-btn:disabled { 
    color: #DADCE0; 
    cursor: not-allowed; 
}

.counter {
    font-weight: 500;
    font-size: 1.1rem;
    color: var(--text-muted);
    min-width: 60px;
    text-align: center;
}

/* Slides Wrapper */
.slides-wrapper {
    position: relative;
    width: 85%;
    max-width: 1200px;
    height: 75%;
}

.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    visibility: hidden;
    /* Soft Google-style upward fade */
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease, visibility 0.6s;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

/* For Google I/O style, we don't do horizontal sliding, just a clean fade up/down */
.slide.left { transform: translateY(-30px); z-index: 1; }
.slide.right { transform: translateY(30px); z-index: 1; }

/* Content Formatting */
.slide-content {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
}

/* Title Slide Styling */
.title-slide {
    text-align: center;
    justify-content: center;
    align-items: center;
}

.google-dots {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
}
.dot { width: 16px; height: 16px; border-radius: 50%; }
.dot.blue { background-color: var(--g-blue); }
.dot.red { background-color: var(--g-red); }
.dot.yellow { background-color: var(--g-yellow); }
.dot.green { background-color: var(--g-green); }

.title-slide h1 {
    font-size: 4.5rem;
    font-weight: 700;
    color: var(--text-main);
    letter-spacing: -1px;
    margin-bottom: 16px;
}
.title-slide h2 {
    font-size: 2rem;
    font-weight: 400;
    color: var(--text-muted);
}

/* Normal Slide Headers */
.header {
    margin-bottom: 40px;
}
.module-tag {
    display: inline-block;
    padding: 6px 16px;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 16px;
}
.tag-blue { background: rgba(66, 133, 244, 0.1); color: var(--g-blue); }
.tag-red { background: rgba(234, 67, 53, 0.1); color: var(--g-red); }
.tag-yellow { background: rgba(251, 188, 5, 0.1); color: #d99a00; }
.tag-green { background: rgba(52, 168, 83, 0.1); color: var(--g-green); }

.header h2 {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--text-main);
    letter-spacing: -0.5px;
}

/* Cards / Content Panels */
.panel {
    background: var(--card-bg);
    border-radius: 24px;
    padding: 50px;
    flex: 1;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    display: flex;
    flex-direction: column;
}

.panel h3 {
    font-size: 2rem;
    font-weight: 500;
    color: var(--text-main);
    margin-bottom: 24px;
}

.panel p {
    font-size: 1.4rem;
    line-height: 1.6;
    color: var(--text-muted);
    margin-bottom: 24px;
}

/* Data / Visual Blocks */
.visualizer-block {
    background: #F1F3F4;
    border-radius: 16px;
    padding: 30px;
    text-align: center;
    margin-top: auto;
    margin-bottom: auto;
}

.code-font {
    font-family: 'Fira Code', monospace;
}

.token-row { margin: 15px 0; font-size: 2rem; display: flex; justify-content: center; gap: 10px; }
.t-chunk { padding: 8px 16px; background: #fff; border-radius: 8px; box-shadow: 0 2px 5px rgba(0,0,0,0.05); font-weight: 500; }
.t-id { padding: 8px 16px; color: var(--text-muted); }

/* Colors for specific concepts */
.c-blue { color: var(--g-blue); }
.c-red { color: var(--g-red); }
.c-green { color: var(--g-green); }
.c-yellow { color: var(--g-yellow); }

.math-block {
    background: #F1F3F4;
    padding: 2rem;
    border-radius: 16px;
    text-align: center;
    font-size: 2.2rem;
    margin: 20px 0;
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-top: 20px;
}
.info-card {
    background: #F8F9FA;
    border: 1px solid #E8EAED;
    padding: 30px;
    border-radius: 16px;
}
.info-card h4 { font-size: 1.4rem; margin-bottom: 12px; font-weight: 600; }
.info-card p { font-size: 1.1rem; margin-bottom: 0; }

.code-block {
    text-align: left;
    background: #202124;
    color: #E8EAED;
}
.code-block pre { margin: 0; font-size: 1.3rem; line-height: 1.6; }

/* Launch Buttons */
.launch-btn {
    display: inline-block;
    margin-top: 30px;
    padding: 15px 30px;
    background-color: var(--g-blue);
    color: white;
    text-decoration: none;
    font-size: 1.4rem;
    font-weight: 500;
    border-radius: 50px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(66, 133, 244, 0.3);
}
.launch-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(66, 133, 244, 0.4);
    color: white;
}
.launch-btn.red { background-color: var(--g-red); box-shadow: 0 4px 15px rgba(234, 67, 53, 0.3); }
.launch-btn.red:hover { box-shadow: 0 6px 20px rgba(234, 67, 53, 0.4); }
.launch-btn.yellow { background-color: var(--g-yellow); box-shadow: 0 4px 15px rgba(251, 188, 5, 0.3); color: #202124;}
.launch-btn.yellow:hover { box-shadow: 0 6px 20px rgba(251, 188, 5, 0.4); color: #202124; }
.launch-btn.green { background-color: var(--g-green); box-shadow: 0 4px 15px rgba(52, 168, 83, 0.3); }
.launch-btn.green:hover { box-shadow: 0 6px 20px rgba(52, 168, 83, 0.4); }