/* ===================================
   CSS Reset & Base Styles
   =================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --success-hover: #059669;
    --danger-color: #ef4444;
    --bg-color: #ffffff;
    --bg-alt: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-color);
}

img {
    max-width: 100%;
    height: auto;
}

/* ===================================
   Navigation
   =================================== */
.navbar {
    background-color: var(--bg-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
    font-weight: 700;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

.nav-link:hover {
    color: var(--primary-color);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger .bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    transition: var(--transition);
}

/* ===================================
   Container
   =================================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ===================================
   Ad Containers
   =================================== */
.ad-container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1rem;
    background-color: var(--bg-alt);
    border: 1px solid var(--border-color);
    margin: 2rem auto;
    max-width: 1200px;
    min-height: 100px;
}

.ad-top {
    margin-top: 0;
}

.ad-bottom {
    margin-bottom: 0;
}

/* ===================================
   Hero Section
   =================================== */
.hero {
    padding: 4rem 0;
    background-color: var(--bg-alt);
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.subtitle {
    text-align: center;
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

.intro-text {
    max-width: 700px;
    margin: 0 auto 3rem;
    text-align: center;
    font-size: 1.05rem;
    line-height: 1.8;
    color: var(--text-secondary);
    padding: 1.5rem;
    background-color: rgba(37, 99, 235, 0.05);
    border-left: 4px solid var(--primary-color);
    border-radius: 8px;
}

/* ===================================
   Upload Area
   =================================== */
.upload-area {
    max-width: 800px;
    margin: 0 auto;
    border: 3px dashed var(--primary-color);
    border-radius: 12px;
    padding: 3rem 2rem;
    text-align: center;
    background-color: var(--bg-color);
    cursor: pointer;
    transition: var(--transition);
}

.upload-area:hover {
    background-color: var(--bg-alt);
    border-color: var(--primary-hover);
}

.upload-area.drag-over {
    background-color: rgba(37, 99, 235, 0.1);
    border-color: var(--primary-hover);
}

.upload-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.upload-icon {
    width: 80px;
    height: 80px;
    color: var(--primary-color);
}

.upload-content h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.upload-content p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* ===================================
   Buttons
   =================================== */
.btn {
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.btn-success:hover {
    background-color: var(--success-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
    background-color: #475569;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

/* ===================================
   File List
   =================================== */
.file-list-container {
    max-width: 800px;
    margin: 2rem auto 0;
}

.file-list-container h3 {
    text-align: center;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.file-list-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.file-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.file-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: move;
    transition: var(--transition);
}

.file-item:hover {
    box-shadow: var(--shadow-md);
}

.file-item.dragging {
    opacity: 0.5;
}

.file-icon {
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #fee2e2;
    border-radius: 8px;
    color: #dc2626;
}

.file-name {
    flex: 1;
    font-weight: 500;
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.file-size {
    flex-shrink: 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.file-remove {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--danger-color);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
}

.file-remove:hover {
    background-color: #dc2626;
    transform: scale(1.1);
}

/* ===================================
   Action Buttons
   =================================== */
.action-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-top: 2rem;
}

/* ===================================
   Progress
   =================================== */
.progress-container {
    max-width: 600px;
    margin: 2rem auto;
    text-align: center;
}

.progress-bar {
    width: 100%;
    height: 24px;
    background-color: var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    margin-bottom: 1rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--success-color));
    width: 0%;
    transition: width 0.3s ease;
    border-radius: 12px;
}

.progress-text {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* ===================================
   Download Container
   =================================== */
.download-container {
    max-width: 600px;
    margin: 2rem auto;
    text-align: center;
    padding: 2rem;
    background-color: var(--bg-color);
    border: 2px solid var(--success-color);
    border-radius: 12px;
}

.download-container h3 {
    color: var(--success-color);
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.download-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    align-items: center;
}

/* ===================================
   Error Message
   =================================== */
.error-message {
    max-width: 600px;
    margin: 2rem auto;
    padding: 1rem;
    background-color: #fee2e2;
    border: 1px solid var(--danger-color);
    color: #991b1b;
    border-radius: 8px;
    text-align: center;
}

/* ===================================
   Features Section
   =================================== */
.features {
    padding: 5rem 0;
    background-color: var(--bg-color);
}

.features h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    padding: 2rem;
    background-color: var(--bg-alt);
    border-radius: 12px;
    text-align: center;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 80px;
    height: 80px;
    margin: 0 auto 1.5rem;
    background-color: rgba(37, 99, 235, 0.1);
    border-radius: 50%;
    color: var(--primary-color);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ===================================
   How It Works Section
   =================================== */
.how-it-works {
    padding: 5rem 0;
    background-color: var(--bg-alt);
}

.how-it-works h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.step {
    text-align: center;
    padding: 1.5rem;
}

.step-number {
    width: 60px;
    height: 60px;
    margin: 0 auto 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--primary-color);
    color: white;
    font-size: 1.5rem;
    font-weight: 700;
    border-radius: 50%;
}

.step h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.step p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ===================================
   FAQ Section
   =================================== */
.faq {
    padding: 5rem 0;
    background-color: var(--bg-color);
}

.faq h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.faq-item {
    max-width: 800px;
    margin: 0 auto 1rem;
}

.faq-details {
    background-color: var(--bg-alt);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem 1.5rem;
    cursor: pointer;
    transition: var(--transition);
}

.faq-details:hover {
    box-shadow: var(--shadow-md);
}

.faq-details summary {
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-primary);
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.faq-details summary::-webkit-details-marker {
    display: none;
}

.faq-details summary::after {
    content: '+';
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.faq-details[open] summary::after {
    content: '−';
}

.faq-details p {
    margin-top: 1rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ===================================
   About Section
   =================================== */
.about {
    padding: 5rem 0;
    background-color: var(--bg-alt);
}

.about h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.about p {
    max-width: 800px;
    margin: 0 auto 1.5rem;
    color: var(--text-secondary);
    line-height: 1.8;
    font-size: 1.05rem;
}

/* ===================================
   Privacy Section
   =================================== */
.privacy {
    padding: 5rem 0;
    background-color: var(--bg-color);
}

.privacy h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.privacy p {
    max-width: 800px;
    margin: 0 auto 1rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.privacy-contact {
    margin-top: 2rem;
    text-align: center;
    font-weight: 600;
    color: var(--text-primary);
}

/* ===================================
   Footer
   =================================== */
.footer {
    background-color: var(--text-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

.footer p {
    margin-bottom: 0.5rem;
}

.footer-tagline {
    color: rgba(255, 255, 255, 0.7);
}

.footer-links {
    margin-top: 1.5rem;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
}

.footer-links a {
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--primary-color);
}

.separator {
    color: rgba(255, 255, 255, 0.5);
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--bg-color);
        width: 100%;
        text-align: center;
        transition: var(--transition);
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
        gap: 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-menu li {
        padding: 1rem 0;
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active .bar:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }

    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }

    .hero h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .upload-area {
        padding: 2rem 1rem;
    }

    .upload-content h3 {
        font-size: 1.2rem;
    }

    .features h2,
    .how-it-works h2,
    .faq h2,
    .about h2,
    .privacy h2 {
        font-size: 1.8rem;
    }

    .feature-grid,
    .steps {
        grid-template-columns: 1fr;
    }

    .action-buttons {
        flex-direction: column;
        align-items: stretch;
    }

    .file-name {
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .hero {
        padding: 2rem 0;
    }

    .hero h1 {
        font-size: 1.5rem;
    }

    .upload-icon {
        width: 50px;
        height: 50px;
    }

    .btn {
        padding: 0.6rem 1.2rem;
        font-size: 0.9rem;
    }
}