/* color variables */
:root {
    --primary: #576A8F;
    --secondary: #B7BDF7;
    --tertiary: #FFF8DE;
    --accent: #FF7444;
    --dark: #1a1a2e;
    --light: #ffffff;
}

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

body {
    font-family: 'DM Sans', sans-serif;
    background: linear-gradient(135deg, var(--dark) 0%, #2d2d44 100%);
    color: var(--tertiary);
    overflow: hidden;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* slide container */
.slide-container {
    width: 90%;
    max-width: 1400px;
    height: 85vh;
    position: relative;
    background: linear-gradient(135deg, rgba(87, 106, 143, 0.1) 0%, rgba(183, 189, 247, 0.05) 100%);
    border-radius: 24px;
    box-shadow: 0 30px 90px rgba(0, 0, 0, 0.5), 
                0 0 0 1px rgba(183, 189, 247, 0.1);
    overflow: hidden;
    backdrop-filter: blur(10px);
}

/* individual slides */
.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transform: translateX(100%) scale(0.95);
    transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    padding: 60px 80px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    overflow-y: auto;
}

.slide.active {
    opacity: 1;
    transform: translateX(0) scale(1);
}

/* typography */
.slide-heading {
    font-family: 'Playfair Display', serif;
    font-size: 3.5rem;
    font-weight: 900;
    color: var(--tertiary);
    margin-bottom: 40px;
    text-align: center;
    position: relative;
    animation: slideInDown 0.6s ease-out;
}

.slide-heading::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 4px;
    background: linear-gradient(90deg, var(--accent), var(--secondary));
    border-radius: 2px;
}

.slide-subtitle {
    font-size: 1.3rem;
    color: var(--secondary);
    margin-bottom: 30px;
    text-align: center;
}

code {
    font-family: 'Space Mono', monospace;
    background: rgba(87, 106, 143, 0.2);
    padding: 4px 10px;
    border-radius: 6px;
    color: var(--secondary);
    font-size: 0.9em;
    border: 1px solid rgba(183, 189, 247, 0.2);
}

/* slide 1: title */
.slide-title {
    position: relative;
    overflow: hidden;
}

.bg-pattern {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 30%, rgba(183, 189, 247, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(255, 116, 68, 0.1) 0%, transparent 50%);
    animation: pulse 8s ease-in-out infinite;
}

.floating-shapes {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    pointer-events: none;
}

.shape {
    position: absolute;
    border-radius: 50%;
    opacity: 0.6;
    animation: float 6s ease-in-out infinite;
}

.shape-1 {
    width: 100px;
    height: 100px;
    background: var(--secondary);
    top: 10%;
    left: 10%;
    animation-delay: 0s;
}

.shape-2 {
    width: 150px;
    height: 150px;
    background: var(--accent);
    top: 60%;
    right: 10%;
    animation-delay: 2s;
}

.shape-3 {
    width: 80px;
    height: 80px;
    background: var(--primary);
    bottom: 15%;
    left: 30%;
    animation-delay: 4s;
}

.main-title {
    font-family: 'Playfair Display', serif;
    font-size: 5rem;
    font-weight: 900;
    color: var(--tertiary);
    text-align: center;
    margin-bottom: 20px;
    animation: slideInUp 0.8s ease-out;
    letter-spacing: -2px;
    line-height: 1.1;
}

.subtitle {
    font-size: 2rem;
    color: var(--secondary);
    text-align: center;
    margin-bottom: 30px;
    animation: slideInUp 0.8s ease-out 0.2s backwards;
}

.instructor {
    font-size: 1.3rem;
    color: var(--accent);
    animation: slideInUp 0.8s ease-out 0.4s backwards;
}

.title-decoration {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-top: 40px;
    animation: slideInUp 0.8s ease-out 0.6s backwards;
}

.deco-line {
    width: 60px;
    height: 2px;
    background: var(--accent);
}

.deco-circle {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--secondary);
}

/* slide: objectives */
.objectives-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
    width: 100%;
    max-width: 1000px;
    animation: fadeIn 0.8s ease-out;
}

.objective-card {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 16px;
    padding: 30px;
    transition: all 0.3s ease;
    animation: slideInUp 0.6s ease-out backwards;
}

.objective-card:nth-child(1) { animation-delay: 0.1s; }
.objective-card:nth-child(2) { animation-delay: 0.2s; }
.objective-card:nth-child(3) { animation-delay: 0.3s; }
.objective-card:nth-child(4) { animation-delay: 0.4s; }

.objective-card:hover {
    transform: translateY(-8px);
    border-color: var(--accent);
    box-shadow: 0 20px 40px rgba(255, 116, 68, 0.2);
}

.objective-number {
    font-family: 'Playfair Display', serif;
    font-size: 3rem;
    font-weight: 900;
    color: var(--accent);
    margin-bottom: 15px;
    opacity: 0.7;
}

.objective-card h3 {
    font-size: 1.5rem;
    color: var(--tertiary);
    margin-bottom: 10px;
}

.objective-card p {
    color: var(--secondary);
    font-size: 1rem;
    line-height: 1.5;
}

/* slide: html intro */
.definition-box {
    margin-bottom: 40px;
    animation: fadeIn 0.6s ease-out;
}

.acronym {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    color: var(--secondary);
}

.letter {
    color: var(--accent);
    font-size: 3rem;
    font-weight: 900;
}

.content-split {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    width: 100%;
    max-width: 1100px;
    animation: slideInUp 0.8s ease-out;
}

.code-panel {
    background: rgba(26, 26, 46, 0.6);
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid rgba(183, 189, 247, 0.2);
}

.code-header {
    background: var(--primary);
    color: var(--tertiary);
    padding: 12px 20px;
    font-weight: 600;
    font-size: 0.9rem;
}

.code-block {
    background: rgba(26, 26, 46, 0.9);
    padding: 25px;
    font-family: 'Space Mono', monospace;
    color: var(--secondary);
    font-size: 1.1rem;
    line-height: 1.8;
    white-space: pre;
}

.code-block.css-code {
    color: #89ddff;
}

.explanation-panel {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 20px;
}

.icon-box {
    font-size: 5rem;
    margin-bottom: 20px;
    animation: bounce 2s ease-in-out infinite;
    color: var(--accent);
}

.icon-box i {
    display: block;
}

.explanation-panel h3 {
    font-size: 2rem;
    color: var(--accent);
    margin-bottom: 15px;
}

.explanation-panel p {
    font-size: 1.2rem;
    color: var(--secondary);
    line-height: 1.6;
}

/* slide: html demo */
.demo-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
    width: 100%;
    max-width: 1100px;
}

.demo-item {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 15px;
    transition: all 0.3s ease;
    animation: fadeIn 0.6s ease-out backwards;
}

.demo-item:nth-child(1) { animation-delay: 0.1s; }
.demo-item:nth-child(2) { animation-delay: 0.2s; }
.demo-item:nth-child(3) { animation-delay: 0.3s; }
.demo-item:nth-child(4) { animation-delay: 0.4s; }
.demo-item:nth-child(5) { animation-delay: 0.5s; }
.demo-item:nth-child(6) { animation-delay: 0.6s; }

.demo-item:hover {
    transform: scale(1.05);
    border-color: var(--accent);
}

.demo-output {
    background: rgba(255, 248, 222, 0.1);
    padding: 15px;
    border-radius: 8px;
    min-height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.demo-button {
    background: var(--accent);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

.demo-button:hover {
    background: var(--primary);
    transform: scale(1.05);
}

.demo-image {
    font-size: 3rem;
    color: var(--secondary);
}

/* slide: box model */
.box-model-visual {
    position: relative;
    display: inline-flex;
    margin: 40px 0;
    animation: fadeIn 0.8s ease-out;
}

.margin-box {
    background: rgba(255, 116, 68, 0.3);
    padding: 30px;
    border: 3px solid var(--accent);
    position: relative;
}

.margin-label {
    position: absolute;
    top: 5px;
    left: 5px;
    font-weight: 700;
    color: var(--accent);
    font-size: 0.9rem;
}

.border-box {
    background: rgba(183, 189, 247, 0.3);
    padding: 25px;
    border: 5px solid var(--secondary);
    position: relative;
}

.border-label {
    position: absolute;
    top: 5px;
    left: 5px;
    font-weight: 700;
    color: var(--secondary);
    font-size: 0.9rem;
}

.padding-box {
    background: rgba(87, 106, 143, 0.3);
    padding: 20px;
    position: relative;
}

.padding-label {
    position: absolute;
    top: 5px;
    left: 5px;
    font-weight: 700;
    color: var(--primary);
    font-size: 0.9rem;
}

.content-box {
    background: var(--tertiary);
    color: var(--dark);
    padding: 30px 50px;
    font-weight: 700;
    font-size: 1.3rem;
}

.box-model-code {
    margin-top: 30px;
    animation: slideInUp 0.8s ease-out;
}

/* slide: interactive box demo */
.interactive-controls {
    display: flex;
    gap: 30px;
    margin-bottom: 40px;
    animation: slideInUp 0.6s ease-out;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.control-group label {
    color: var(--secondary);
    font-weight: 600;
    font-size: 1rem;
}

input[type="range"] {
    width: 200px;
    height: 6px;
    background: rgba(183, 189, 247, 0.2);
    border-radius: 3px;
    outline: none;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.demo-box-container {
    background: rgba(26, 26, 46, 0.3);
    padding: 60px;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeIn 0.8s ease-out;
}

.demo-box {
    background: rgba(255, 116, 68, 0.3);
    border: 5px solid var(--accent);
    transition: all 0.3s ease;
}

.demo-box-content {
    background: var(--tertiary);
    color: var(--dark);
    padding: 30px 50px;
    font-weight: 700;
    font-size: 1.5rem;
}

/* slide: colors */
.color-methods {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
    width: 100%;
    max-width: 1100px;
}

.color-card {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
    text-align: center;
    transition: all 0.3s ease;
    animation: fadeIn 0.6s ease-out backwards;
}

.color-card:nth-child(1) { animation-delay: 0.1s; }
.color-card:nth-child(2) { animation-delay: 0.2s; }
.color-card:nth-child(3) { animation-delay: 0.3s; }
.color-card:nth-child(4) { animation-delay: 0.4s; }

.color-card:hover {
    transform: translateY(-10px);
    border-color: var(--accent);
}

.color-sample {
    width: 100%;
    height: 80px;
    border-radius: 8px;
    margin-bottom: 15px;
    border: 3px solid rgba(255, 255, 255, 0.3);
}

.color-card h3 {
    font-size: 1.2rem;
    color: var(--tertiary);
    margin-bottom: 10px;
}

.color-card p {
    font-size: 0.9rem;
    color: var(--secondary);
    margin-top: 10px;
}

/* slide: typography */
.typo-examples {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
    width: 100%;
    max-width: 1000px;
    margin-bottom: 40px;
}

.typo-box {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
    text-align: center;
}

.typo-sample {
    font-size: 1.5rem;
    color: var(--tertiary);
    margin-top: 15px;
}

.typo-properties {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    width: 100%;
    max-width: 800px;
}

.prop-item {
    background: rgba(26, 26, 46, 0.4);
    padding: 20px;
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    align-items: center;
    border: 1px solid rgba(183, 189, 247, 0.2);
}

.prop-item span, .prop-item div {
    color: var(--tertiary);
    font-size: 1.3rem;
}

/* slide: display */
.display-demos {
    display: flex;
    flex-direction: column;
    gap: 30px;
    width: 100%;
    max-width: 1000px;
}

.display-section {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
}

.display-section h3 {
    color: var(--accent);
    font-size: 1.3rem;
    margin-bottom: 15px;
}

.display-container {
    background: rgba(26, 26, 46, 0.4);
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 10px;
}

.block-item {
    background: var(--secondary);
    color: var(--dark);
    padding: 15px;
    margin: 10px 0;
    border-radius: 6px;
    font-weight: 600;
}

.inline-block-item {
    display: inline-block;
    background: var(--accent);
    color: white;
    padding: 15px 25px;
    margin: 5px;
    border-radius: 6px;
    font-weight: 600;
}

.flex-container {
    display: flex;
    gap: 15px;
}

.flex-item {
    background: var(--primary);
    color: white;
    padding: 20px;
    border-radius: 6px;
    flex: 1;
    text-align: center;
    font-weight: 600;
}

.display-note {
    color: var(--secondary);
    font-size: 0.95rem;
    font-style: italic;
}

/* slide: flexbox */
.flexbox-playground {
    width: 100%;
    max-width: 1000px;
}

.flex-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 30px;
    justify-content: center;
}

.flex-btn {
    background: var(--primary);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
    font-family: 'Space Mono', monospace;
    font-size: 0.85rem;
}

.flex-btn:hover {
    background: var(--accent);
    transform: translateY(-2px);
}

.flex-demo-container {
    display: flex;
    flex-direction: row;
    justify-content: flex-start;
    background: rgba(26, 26, 46, 0.6);
    padding: 40px;
    border-radius: 12px;
    min-height: 250px;
    border: 2px solid var(--secondary);
    transition: all 0.5s ease;
}

.flex-demo-item {
    background: var(--accent);
    color: white;
    width: 100px;
    height: 100px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    border-radius: 8px;
    transition: all 0.5s ease;
}

/* slide: positioning */
.position-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
    width: 100%;
    max-width: 1000px;
}

.position-card {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
}

.position-card h3 {
    color: var(--accent);
    font-size: 1.5rem;
    margin-bottom: 10px;
    font-family: 'Space Mono', monospace;
}

.position-card p {
    color: var(--secondary);
    font-size: 1rem;
    margin-bottom: 15px;
}

.position-demo {
    background: rgba(26, 26, 46, 0.4);
    height: 120px;
    border-radius: 8px;
    position: relative;
    overflow: hidden;
}

.position-demo-parent {
    position: relative;
}

.pos-static,
.pos-relative,
.pos-absolute,
.pos-fixed-demo {
    background: var(--accent);
    color: white;
    padding: 15px 25px;
    border-radius: 6px;
    font-weight: 700;
}

.pos-static {
    position: static;
}

.pos-relative {
    position: relative;
    top: 20px;
    left: 20px;
}

.pos-absolute {
    position: absolute;
    top: 20px;
    right: 20px;
}

.pos-fixed-demo {
    position: absolute;
    bottom: 10px;
    right: 10px;
    font-size: 0.9rem;
}

/* slide: hover & transitions */
.hover-examples {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 25px;
    width: 100%;
    max-width: 900px;
    margin-bottom: 30px;
}

.hover-box {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.hover-box h3 {
    color: var(--tertiary);
    font-size: 1.5rem;
    margin-bottom: 15px;
}

.hover-scale:hover {
    transform: scale(1.15);
    border-color: var(--accent);
}

.hover-rotate:hover {
    transform: rotate(5deg);
    border-color: var(--secondary);
}

.hover-color {
    background: rgba(87, 106, 143, 0.15);
}

.hover-color:hover {
    background: linear-gradient(135deg, var(--accent), var(--primary));
    border-color: transparent;
}

.hover-shadow:hover {
    box-shadow: 0 25px 50px rgba(255, 116, 68, 0.4);
    transform: translateY(-10px);
    border-color: var(--accent);
}

.transition-code {
    animation: fadeIn 1s ease-out;
}

/* slide: pseudo-classes */
.pseudo-examples {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
    width: 100%;
    max-width: 1000px;
}

.pseudo-demo {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
    text-align: center;
}

.pseudo-demo h3 {
    color: var(--accent);
    font-size: 1.3rem;
    margin-bottom: 15px;
    font-family: 'Space Mono', monospace;
}

.pseudo-btn {
    background: var(--primary);
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    margin: 15px 0;
    transition: all 0.3s ease;
}

.pseudo-btn:hover {
    background: var(--secondary);
    color: var(--dark);
}

.pseudo-btn:active {
    transform: scale(0.95);
}

.pseudo-input {
    background: rgba(26, 26, 46, 0.6);
    border: 2px solid rgba(183, 189, 247, 0.3);
    color: var(--tertiary);
    padding: 12px;
    border-radius: 6px;
    width: 100%;
    margin: 15px 0;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.pseudo-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(255, 116, 68, 0.2);
}

.pseudo-list {
    list-style: none;
    text-align: left;
    margin: 15px 0;
}

.pseudo-list li {
    padding: 10px;
    margin: 5px 0;
    background: rgba(26, 26, 46, 0.3);
    border-radius: 6px;
}

.pseudo-list li:first-child {
    color: var(--accent);
    font-weight: 700;
    background: rgba(255, 116, 68, 0.2);
}

.pseudo-demo code {
    display: block;
    margin-top: 15px;
}

/* slide: responsive */
.responsive-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    width: 100%;
    max-width: 1100px;
}

.responsive-info {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.responsive-info h3 {
    color: var(--accent);
    font-size: 2rem;
    margin-bottom: 20px;
}

.media-query-example {
    background: rgba(26, 26, 46, 0.6);
    border-radius: 12px;
    padding: 20px;
    margin: 20px 0;
}

.media-query-example code {
    display: block;
    line-height: 1.8;
    background: transparent;
    border: none;
    padding: 0;
}

.responsive-info p {
    color: var(--secondary);
    font-size: 1.1rem;
}

.responsive-devices {
    display: flex;
    align-items: center;
    justify-content: space-around;
    gap: 20px;
}

.device {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.desktop .screen {
    width: 200px;
    height: 120px;
    background: var(--primary);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    color: white;
    font-weight: 600;
    border: 3px solid var(--secondary);
}

.desktop .screen i {
    font-size: 2.5rem;
}

.tablet .screen {
    width: 120px;
    height: 160px;
    background: var(--accent);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    color: white;
    font-weight: 600;
    border: 3px solid var(--secondary);
}

.tablet .screen i {
    font-size: 2rem;
}

.mobile .screen {
    width: 80px;
    height: 140px;
    background: var(--secondary);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 6px;
    color: var(--dark);
    font-weight: 600;
    font-size: 0.8rem;
    border: 3px solid var(--primary);
}

.mobile .screen i {
    font-size: 1.5rem;
}

/* slide: cheat sheet */
.cheatsheet-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
    width: 100%;
    max-width: 1200px;
}

.cheat-category {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
}

.cheat-category h3 {
    color: var(--accent);
    font-size: 1.3rem;
    margin-bottom: 15px;
    text-align: center;
}

.cheat-category ul {
    list-style: none;
}

.cheat-category li {
    padding: 8px 0;
    border-bottom: 1px solid rgba(183, 189, 247, 0.1);
}

.cheat-category li:last-child {
    border-bottom: none;
}

/* slide: activity */
.activity-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    width: 100%;
    max-width: 1200px;
}

.activity-instructions h3,
.activity-challenge h3 {
    color: var(--accent);
    font-size: 1.8rem;
    margin-bottom: 20px;
}

.instruction-steps {
    margin-bottom: 20px;
}

.instruction-steps p {
    color: var(--secondary);
    font-size: 1.1rem;
    margin-bottom: 12px;
    line-height: 1.6;
}

.activity-challenge {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 30px;
}

.challenge-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.challenge-item {
    display: flex;
    align-items: center;
    gap: 15px;
    background: rgba(26, 26, 46, 0.4);
    padding: 15px 20px;
    border-radius: 8px;
    border-left: 4px solid var(--secondary);
    transition: all 0.3s ease;
}

.challenge-item:hover {
    transform: translateX(10px);
    border-left-color: var(--accent);
}

.challenge-item.bonus {
    border-left-color: var(--accent);
    background: rgba(255, 116, 68, 0.1);
}

.challenge-icon {
    font-size: 24px;
    color: var(--secondary);
    flex-shrink: 0;
}

.challenge-item.bonus .challenge-icon {
    color: var(--accent);
}

.challenge-item span {
    color: var(--tertiary);
    font-size: 1rem;
    line-height: 1.5;
}

/* slide: quiz */
.quiz-container {
    width: 100%;
    max-width: 900px;
}

.question-box {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 16px;
    padding: 40px;
    margin-bottom: 30px;
}

.question-number {
    color: var(--accent);
    font-weight: 700;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 20px;
}

.question-text {
    color: var(--tertiary);
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 30px;
    line-height: 1.4;
}

.answer-options {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin-bottom: 20px;
}

.answer-btn {
    background: rgba(26, 26, 46, 0.6);
    color: var(--tertiary);
    border: 2px solid rgba(183, 189, 247, 0.2);
    padding: 18px 25px;
    border-radius: 10px;
    cursor: pointer;
    font-size: 1.1rem;
    text-align: left;
    transition: all 0.3s ease;
    font-family: 'DM Sans', sans-serif;
}

.answer-btn:hover {
    background: rgba(87, 106, 143, 0.3);
    border-color: var(--secondary);
    transform: translateX(10px);
}

.answer-btn.correct {
    background: rgba(76, 175, 80, 0.3);
    border-color: #4caf50;
    color: #4caf50;
    font-weight: 600;
}

.answer-btn.incorrect {
    background: rgba(244, 67, 54, 0.3);
    border-color: #f44336;
    color: #f44336;
}

.answer-btn:disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

.feedback {
    margin-top: 20px;
    padding: 15px 20px;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    text-align: center;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.feedback i {
    margin-right: 8px;
    font-size: 1.2rem;
}

.feedback.show {
    opacity: 1;
}

.feedback.correct {
    background: rgba(76, 175, 80, 0.2);
    color: #4caf50;
    border: 2px solid #4caf50;
}

.feedback.incorrect {
    background: rgba(244, 67, 54, 0.2);
    color: #f44336;
    border: 2px solid #f44336;
}

.next-question-btn {
    width: 100%;
    background: var(--accent);
    color: white;
    border: none;
    padding: 15px;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    margin-top: 20px;
    transition: all 0.3s ease;
}

.next-question-btn:hover {
    background: var(--primary);
    transform: translateY(-2px);
}

.score-display {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 15px;
    background: rgba(26, 26, 46, 0.6);
    padding: 20px 40px;
    border-radius: 12px;
    border: 2px solid var(--accent);
}

.score-label {
    color: var(--secondary);
    font-size: 1.3rem;
    font-weight: 600;
}

.score-value {
    color: var(--accent);
    font-size: 2rem;
    font-weight: 900;
    font-family: 'Space Mono', monospace;
}

/* slide: thank you */
.slide-thank-you {
    background: radial-gradient(circle at center, rgba(255, 116, 68, 0.1), transparent);
}

.thank-you-content {
    text-align: center;
    animation: fadeIn 0.8s ease-out;
}

.thank-you-title {
    font-family: 'Playfair Display', serif;
    font-size: 6rem;
    font-weight: 900;
    color: var(--tertiary);
    margin-bottom: 30px;
    animation: slideInUp 0.8s ease-out;
}

.thank-you-subtitle {
    font-size: 2.5rem;
    color: var(--accent);
    margin-bottom: 40px;
    animation: slideInUp 0.8s ease-out 0.2s backwards;
}

.thank-you-decoration {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin: 40px 0;
    animation: fadeIn 1s ease-out 0.4s backwards;
}

.decoration-element {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    animation: pulse 2s ease-in-out infinite;
}

.decoration-element:nth-child(1) {
    background: var(--primary);
    animation-delay: 0s;
}

.decoration-element:nth-child(2) {
    background: var(--accent);
    animation-delay: 0.3s;
}

.decoration-element:nth-child(3) {
    background: var(--secondary);
    animation-delay: 0.6s;
}

.contact-info {
    font-size: 1.5rem;
    color: var(--secondary);
    animation: slideInUp 0.8s ease-out 0.6s backwards;
}

/* controls */
.controls {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    align-items: center;
    gap: 25px;
    z-index: 100;
    background: rgba(26, 26, 46, 0.8);
    padding: 15px 30px;
    border-radius: 50px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(183, 189, 247, 0.2);
}

button {
    padding: 12px 25px;
    background: var(--accent);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 700;
    font-size: 1rem;
    color: white;
    transition: all 0.3s ease;
    font-family: 'DM Sans', sans-serif;
}

button:hover {
    background: var(--primary);
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(255, 116, 68, 0.3);
}

button:active {
    transform: translateY(0);
}

#slide-indicator {
    color: var(--tertiary);
    font-weight: 600;
    font-size: 1.1rem;
    min-width: 80px;
    text-align: center;
    font-family: 'Space Mono', monospace;
}

/* progress bar */
.progress-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 6px;
    background: rgba(87, 106, 143, 0.2);
    z-index: 100;
}

.progress-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent), var(--secondary));
    transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 0 20px rgba(255, 116, 68, 0.5);
}

/* selector slide */
.selector-examples {
    display: flex;
    flex-direction: column;
    gap: 25px;
    width: 100%;
    max-width: 800px;
}

.selector-box {
    background: rgba(87, 106, 143, 0.15);
    border: 2px solid rgba(183, 189, 247, 0.2);
    border-radius: 12px;
    padding: 25px;
    transition: all 0.3s ease;
}

.selector-box:hover {
    border-color: var(--accent);
    transform: translateX(10px);
}

.selector-type {
    color: var(--accent);
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 10px;
}

.selector-box code {
    display: block;
    margin: 15px 0;
    font-size: 1.2rem;
}

.selector-desc {
    color: var(--secondary);
    font-size: 1rem;
}

/* animations */
@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInDown {
    from {
        opacity: 0;
        transform: translateY(-40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-30px);
    }
}

@keyframes pulse {
    0%, 100% {
        opacity: 0.6;
        transform: scale(1);
    }
    50% {
        opacity: 1;
        transform: scale(1.05);
    }
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

/* responsive */
@media (max-width: 1200px) {
    .slide {
        padding: 40px 50px;
    }
    
    .main-title {
        font-size: 4rem;
    }
    
    .slide-heading {
        font-size: 3rem;
    }
}

@media (max-width: 768px) {
    .slide {
        padding: 30px 25px;
    }
    
    .objectives-grid,
    .demo-grid,
    .color-methods,
    .position-grid,
    .hover-examples,
    .pseudo-examples,
    .resources-grid,
    .activity-steps,
    .cheatsheet-grid {
        grid-template-columns: 1fr;
    }
    
    .content-split,
    .responsive-content {
        grid-template-columns: 1fr;
    }
    
    .main-title {
        font-size: 2.5rem;
    }
    
    .slide-heading {
        font-size: 2rem;
    }
    
    .controls {
        bottom: 20px;
        gap: 15px;
        padding: 10px 20px;
    }
    
    button {
        padding: 10px 15px;
        font-size: 0.9rem;
    }
}