/* CSS Variables for Theming */
:root {
    --bg-color: #f8fafc;
    --text-color: #0f172a;
    --nav-bg: #ffffff;
    --card-bg: #ffffff;
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --success-color: #10b981;
    --success-hover: #059669;
    --shadow-soft: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --border-color: #e2e8f0;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --bg-color: #000000;
    --text-color: #f8fafc;
    --nav-bg: #252222;
    --card-bg: #1e293b;
    --primary-color: #60a5fa;
    --primary-hover: #3b82f6;
    --success-color: #34d399;
    --success-hover: #10b981;
    --shadow-soft: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
    --shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.7);
    --border-color: #334155;
}

/* Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    transition: background-color 0.3s ease, color 0.3s ease;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

.text-center { text-align: center; }
.hidden { display: none !important; }

/* Navigation */
nav {
    background-color: var(--nav-bg);
    box-shadow: var(--shadow-soft);
    position: relative;
    z-index: 100;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 15px 20px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
    letter-spacing: 1px;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 20px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -4px;
    left: 0;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

.nav-links a:hover::after { width: 100%; }

.theme-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.theme-btn:hover {
    transform: rotate(20deg) scale(1.1);
}

/* Sections & Cards */
.section { padding: 80px 0; }
.alternate-bg { background-color: rgba(0,0,0,0.02); }

[data-theme="dark"] .alternate-bg { background-color: rgba(255,255,255,0.02); }

h1, h2, h3 { margin-bottom: 20px; }

/* Cool Hovering Animations for Cards */
.hover-anim {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow-soft);
    transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275), box-shadow 0.4s ease;
}

.hover-anim:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
}

/* Converter Tool UI */
.converter-card {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.upload-area {
    margin: 30px 0;
    padding: 40px 20px;
    border: 2px dashed var(--primary-color);
    border-radius: 8px;
    background-color: rgba(59, 130, 246, 0.05);
}

input[type="file"] {
    font-size: 1rem;
    color: var(--text-color);
}

.controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

select {
    padding: 10px 15px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    background: var(--nav-bg);
    color: var(--text-color);
    font-size: 1rem;
    cursor: pointer;
}

.btn {
    padding: 10px 25px;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    color: #fff;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

.btn:hover { transform: scale(1.05); }

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

.success-btn { background-color: var(--success-color); text-decoration: none; display: inline-block; }
.success-btn:hover { background-color: var(--success-hover); }

/* Output Area */
.output-area { margin-top: 30px; }
#previewImg {
    max-width: 100%;
    max-height: 300px;
    border-radius: 8px;
    margin-bottom: 20px;
    box-shadow: var(--shadow-soft);
}

/* FAQ */
.faq-item {
    margin-bottom: 20px;
    text-align: left;
}

/* Footer */
footer {
    text-align: center;
    padding: 30px;
    background-color: var(--nav-bg);
    border-top: 1px solid var(--border-color);
}

/* Fully Optimized Mobile Responsive Layout Breakpoints */
@media (max-width: 768px) {
    /* Responsive Grid Structure for Header Element Layout alignment */
    .nav-container {
        display: grid;
        grid-template-columns: 1fr auto;
        gap: 12px;
        padding: 12px 15px;
    }
    .logo {
        grid-column: 1;
        font-size: 1.3rem;
    }
    .theme-btn {
        grid-column: 2;
        font-size: 1.3rem;
    }
    .nav-links {
        grid-column: 1 / span 2;
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px 15px;
        padding-top: 10px;
        border-top: 1px solid var(--border-color);
        width: 100%;
    }
    
    /* Typography Scaling Updates */
    .section {
        padding: 40px 0;
    }
    h1 {
        font-size: 1.85rem;
    }
    h2 {
        font-size: 1.5rem;
    }
    h3 {
        font-size: 1.15rem;
    }
    
    /* Box Component Cushion & Insets Optimization */
    .hover-anim {
        padding: 20px 15px;
    }
    .upload-area {
        margin: 20px 0;
        padding: 25px 15px;
    }
    
    /* Controls Vertical Form Stack Optimization */
    .controls {
        flex-direction: column;
        align-items: stretch;
        width: 100%;
        max-width: 320px;
        margin: 0 auto 20px auto;
        gap: 12px;
    }
    .controls select,
    .controls .btn {
        width: 100%;
        text-align: center;
    }
    
    /* File Select Asset Safety Wrappers */
    input[type="file"] {
        font-size: 0.9rem;
        max-width: 100%;
    }
    #previewImg {
        max-height: 220px;
    }
}