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

:root {
    --bg-primary: #fafafa;
    --bg-secondary: #ffffff;
    --bg-card: #e8e8e8;
    --text-primary: #333;
    --text-secondary: #555;
    --text-muted: #999;
    --accent: #ff5757;
    --accent-hover: #ff3838;
    --accent-secondary: #ffa726;
    --accent-secondary-hover: #ff9800;
    --shadow-sm: rgba(0,0,0,0.05);
    --shadow-md: rgba(0,0,0,0.1);
    --shadow-lg: rgba(0,0,0,0.5);
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-card: #3d3d3d;
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-muted: #808080;
    --accent: #ff6b6b;
    --accent-hover: #ff5252;
    --accent-secondary: #ffb74d;
    --accent-secondary-hover: #ffa726;
    --shadow-sm: rgba(0,0,0,0.3);
    --shadow-md: rgba(0,0,0,0.4);
    --shadow-lg: rgba(0,0,0,0.6);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    background: var(--bg-secondary);
    padding: 20px 0;
    box-shadow: 0 2px 5px var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color 0.3s ease;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 40px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 600;
    font-size: 16px;
}

.logo-icon {
    width: 30px;
    height: 30px;
    background: var(--accent);
    border-radius: 5px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    font-size: 14px;
    transition: transform 0.3s ease;
}

.logo-icon:hover {
    transform: rotate(360deg);
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 15px;
}

.theme-toggle, .lang-toggle, .back-link i {
    background: var(--bg-primary);
    border: none;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    color: var(--text-primary);
    font-size: 16px;
}

.theme-toggle:hover, .lang-toggle:hover, .back-link i:hover {
    background: var(--accent);
    color: white;
    transform: scale(1.1);
}

.lang-toggle {
    width: auto;
    padding: 6px 12px;
    font-size: 12px;
    font-weight: 600;
    border-radius: 18px;
}

.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

.slide-up {
    opacity: 0;
    transform: translateY(50px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.slide-up.visible {
    opacity: 1;
    transform: translateY(0);
}

.zoom-in {
    opacity: 0;
    transform: scale(0.9);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.zoom-in.visible {
    opacity: 1;
    transform: scale(1);
}

.project-hero {
    max-width: 900px;
    margin: 60px auto;
    padding: 0 40px;
    text-align: center;
}

.project-category {
    color: var(--accent);
    font-size: 14px;
    letter-spacing: 1px;
    margin-bottom: 15px;
    text-transform: uppercase;
    font-weight: 600;
}

.project-hero h1 {
    font-size: 48px;
    font-weight: 800;
    margin-bottom: 40px;
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-image {
    width: 100%;
    border-radius: 20px;
    overflow: hidden;
    box-shadow: 0 10px 40px var(--shadow-lg);
    background: var(--bg-card);
    padding: 10px;
    transition: transform 0.3s ease;
}

.hero-image:hover {
    transform: scale(1.02);
}

.hero-image img {
    width: 100%;
    border-radius: 10px;
}

.project-info {
    max-width: 1200px;
    margin: 60px auto;
    padding: 0 40px;
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 60px;
}

.info-main h2 {
    font-size: 32px;
    margin-bottom: 20px;
    font-weight: 700;
    color: var(--text-primary);
}

.info-main p {
    color: var(--text-secondary);
    line-height: 1.8;
    font-size: 16px;
}

.info-sidebar {
    background: var(--bg-secondary);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 4px 20px var(--shadow-sm);
    height: fit-content;
    transition: all 0.3s ease;
}

.info-sidebar:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px var(--shadow-md);
}

.info-item {
    margin-bottom: 25px;
}

.info-item:last-child {
    margin-bottom: 0;
}

.info-label {
    font-size: 12px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 5px;
}

.info-value {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

.process-section {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 40px;
}

.process-section h2 {
    font-size: 32px;
    margin-bottom: 20px;
    font-weight: 700;
}

.process-section p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 40px;
    font-size: 16px;
}

/* Challenge Section */
.challenge-section {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 40px;
}

.challenge-section h2 {
    font-size: 32px;
    margin-bottom: 20px;
    font-weight: 700;
}

.challenge-section p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 40px;
    font-size: 16px;
}

.challenge-images {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

.challenge-img {
    width: 100%;
    height: 350px;
    border-radius: 15px;
    overflow: hidden;
}

.sketch-img {
    background: var(--bg-card);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 10px;
    box-shadow: 0 4px 20px var(--shadow-lg);
    transition: transform 0.3s ease;
}

.sketch-img:hover {
    transform: scale(1.05);
}

.sketch-img img {
    border-radius: 10px;
}

.action-buttons {
    max-width: 1200px;
    margin: 60px auto;
    padding: 0 40px;
    display: flex;
    justify-content: center;
    gap: 20px;
}

.btn {
    padding: 15px 35px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
    font-size: 16px;
    display: inline-block;
}

.btn-primary {
    background: var(--accent);
    color: white;
}

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-3px);
    box-shadow: 0 5px 20px rgba(255, 87, 87, 0.4);
}

.btn-secondary {
    background: var(--accent-secondary);
    color: white;
}

.btn-secondary:hover {
    background: var(--accent-secondary-hover);
    transform: translateY(-3px);
    box-shadow: 0 5px 20px rgba(255, 167, 38, 0.4);
}

.project-navigation {
    max-width: 1200px;
    margin: 80px auto 40px;
    padding: 0 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 600;
    transition: all 0.3s;
    padding: 12px 20px;
    border-radius: 25px;
    background: var(--bg-secondary);
}

.nav-link:hover {
    color: var(--accent);
    transform: translateX(-5px);
    box-shadow: 0 4px 15px var(--shadow-md);
}

.nav-link.next:hover {
    transform: translateX(5px);
}

.nav-link span {
    font-size: 20px;
}

@media (max-width: 768px) {
    .project-hero h1 {
        font-size: 32px;
    }

    .project-info {
        grid-template-columns: 1fr;
    }

    .challenge-images {
        grid-template-columns: 1fr;
    }

    .action-buttons {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        text-align: center;
    }

    .project-navigation {
        flex-direction: column;
        gap: 20px;
    }

    nav {
        padding: 0 20px;
    }

    .nav-right {
        gap: 10px;
    }
}