:root {
    --primary: #4361ee;
    --primary-dark: #3f37c9;
    --secondary: #4cc9f0;
    --accent: #7209b7;
    --light: #f8f9fa;
    --dark: #212529;
    --success: #2ecc71;
    --success-dark: #27ae60;
    --warning: #f9c74f;
    --danger: #e74c3c;
    --gray: #6c757d;
    --light-gray: #e9ecef;
    --border-radius: 12px;
    --box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: #f8fafc;
    color: var(--dark);
    line-height: 1.6;
    min-height: 100vh;
    padding-top: 80px;
}

/* Header & Navigation */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: white;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.1);
    z-index: 1000;
    padding: 15px 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
}

.logo i {
    color: var(--accent);
}

.nav-links {
    display: flex;
    gap: 25px;
    align-items: center;
}

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

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

.nav-links .active {
    color: var(--primary);
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    border-radius: 50px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(67, 97, 238, 0.3);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Hero Section */
.hero {
    display: flex;
    align-items: center;
    gap: 50px;
    padding: 60px 0;
    margin-bottom: 60px;
}

.hero-content {
    flex: 1;
}

.hero h1 {
    font-size: 3rem;
    line-height: 1.2;
    margin-bottom: 20px;
    margin-left: 20px;
    color: var(--dark);
}

.hero p {
    font-size: 1.2rem;
    color: var(--gray);
    margin-bottom: 30px;
    margin-left: 20px;
    max-width: 600px;
}

.hero-image {
    flex: 1;
    display: flex;
    justify-content: center;
}

.hero-image img {
    max-width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.hero-buttons {
    display: flex;
    gap: 15px;
    margin-top: 20px;
    margin-left: 20px;
}

/* Converter Tool */
.tool-container {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    overflow: hidden;
    margin-bottom: 60px;
}

.tool-header {
    padding: 25px 30px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
}

.tool-header h2 {
    font-size: 1.8rem;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.tool-header p {
    opacity: 0.9;
}

.tool-content {
    padding: 30px;
    display: flex;
    flex-wrap: wrap;
    gap: 30px;
}

.upload-section, .result-section {
    flex: 1;
    min-width: 300px;
}

.section-title {
    font-size: 1.3rem;
    margin-bottom: 20px;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.section-title i {
    color: var(--primary);
}

.drop-area {
    border: 3px dashed var(--primary);
    border-radius: var(--border-radius);
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background-color: var(--light);
    margin-bottom: 20px;
    position: relative;
}

.drop-area:hover, .drop-area.drag-over {
    background-color: rgba(67, 97, 238, 0.05);
    border-color: var(--primary-dark);
}

.drop-area p {
    margin: 10px 0;
    color: var(--gray);
}

.drop-icon {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: 15px;
}

.file-input {
    display: none;
}

.browse-btn {
    display: inline-block;
    background: var(--primary);
    color: white;
    padding: 12px 25px;
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
    margin-top: 15px;
    border: none;
    font-size: 1rem;
}

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

.preview-container {
    margin-top: 30px;
}

.preview-title {
    font-size: 1.1rem;
    margin-bottom: 15px;
    color: var(--dark);
    font-weight: 500;
}

.image-preview {
    width: 100%;
    border-radius: var(--border-radius);
    border: 1px solid var(--light-gray);
    max-height: 300px;
    object-fit: contain;
    background: var(--light);
    display: none;
}

.placeholder {
    width: 100%;
    height: 300px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: var(--light);
    border-radius: var(--border-radius);
    border: 1px dashed var(--light-gray);
    color: var(--gray);
}

.placeholder i {
    font-size: 3rem;
    margin-bottom: 15px;
    color: var(--light-gray);
}

.result-content {
    display: none;
}

.converted-preview {
    width: 100%;
    height: 450px;
    border-radius: var(--border-radius);
    border: 1px solid var(--light-gray);
    background: var(--light);
    overflow: auto;
    padding: 15px;
}

.converted-preview svg {
    width: 100%;
    height: 100%;
}

.download-btn {
    display: block;
    width: 100%;
    background: var(--success);
    color: white;
    padding: 15px;
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
    margin-top: 25px;
    border: none;
    font-size: 1.1rem;
    text-align: center;
    text-decoration: none;
}

.download-btn:hover {
    background: var(--success-dark);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(46, 204, 113, 0.3);
}

.download-btn:disabled {
    background: var(--light-gray);
    cursor: not-allowed;
}

.loading {
    display: none;
    text-align: center;
    margin: 20px 0;
}

.loader {
    border: 5px solid #f3f3f3;
    border-top: 5px solid var(--primary);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto 15px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.error-message {
    color: var(--danger);
    background: #fdeded;
    padding: 10px 15px;
    border-radius: 8px;
    margin: 10px 0;
    display: none;
    font-weight: 500;
}

/* Features Section */
.features {
    background: white;
    border-radius: var(--border-radius);
    padding: 60px 30px;
    box-shadow: var(--box-shadow);
    margin-bottom: 60px;
}

.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-header h2 {
    font-size: 2.2rem;
    margin-bottom: 15px;
    color: var(--dark);
}

.section-header p {
    color: var(--gray);
    max-width: 700px;
    margin: 0 auto;
    font-size: 1.1rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.feature-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 30px;
    text-align: center;
    transition: var(--transition);
    border: 1px solid var(--light-gray);
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 20px;
    width: 80px;
    height: 80px;
    background: rgba(67, 97, 238, 0.1);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
}

.feature-card h3 {
    margin-bottom: 15px;
    color: var(--dark);
    font-size: 1.4rem;
}

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

/* How It Works Section */
.workflow {
    margin-bottom: 60px;
}

.steps {
    display: flex;
    flex-wrap: wrap;
    gap: 30px;
    justify-content: center;
    margin-top: 40px;
}

.step {
    flex: 1;
    min-width: 250px;
    text-align: center;
    padding: 30px 20px;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    transition: var(--transition);
}

.step:hover {
    transform: translateY(-10px);
}

.step-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--primary);
    color: white;
    border-radius: 50%;
    font-size: 1.5rem;
    font-weight: bold;
    margin: 0 auto 20px;
}

.step h3 {
    margin-bottom: 15px;
    color: var(--dark);
}

.step p {
    color: var(--gray);
}

/* FAQ Section */
.faq {
    margin-bottom: 60px;
}

.faq-container {
    max-width: 800px;
    margin: 40px auto 0;
}

.faq-item {
    margin-bottom: 15px;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    overflow: hidden;
}

.faq-question {
    padding: 20px;
    background: white;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-question i {
    transition: var(--transition);
}

.faq-answer {
    padding: 0 20px;
    max-height: 0;
    overflow: hidden;
    transition: var(--transition);
    background: var(--light);
}

.faq-item.active .faq-answer {
    padding: 20px;
    max-height: 500px;
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

/* Footer */
footer {
    background: var(--dark);
    color: white;
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-column h3 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
}

.footer-column h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 2px;
    background: var(--primary);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a {
    color: #adb5bd;
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: white;
    padding-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid #343a40;
    color: #adb5bd;
    font-size: 0.9rem;
}

.social-links {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

.social-links a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: #343a40;
    color: white;
    transition: var(--transition);
}

.social-links a:hover {
    background: var(--primary);
    transform: translateY(-3px);
}

/* Responsive Design */
@media (max-width: 992px) {
    .hero {
        flex-direction: column;
        text-align: center;
    }
    
    .hero-content {
        display: flex;
        flex-direction: column;
        align-items: center;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .nav-links {
        display: none;
    }
}

@media (max-width: 768px) {
    .tool-content {
        flex-direction: column;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        gap: 10px;
    }
    
    .btn {
        width: 100%;
    }
    
    .steps {
        flex-direction: column;
    }
}

@media (max-width: 576px) {
    .navbar {
        flex-direction: column;
        gap: 15px;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .section-header h2 {
        font-size: 1.8rem;
    }
}

/* PowerPoint Guide Section */
.powerpoint-guide {
    margin-bottom: 60px;
}

.guide-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 25px;
    margin-top: 40px;
}

.guide-step {
    background: white;
    border-radius: var(--border-radius);
    padding: 25px 20px;
    text-align: center;
    box-shadow: var(--box-shadow);
    transition: var(--transition);
}

.guide-step:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
}

.guide-icon {
    width: 70px;
    height: 70px;
    background: rgba(67, 97, 238, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    color: var(--primary);
    font-size: 1.8rem;
}

.guide-step h3 {
    margin-bottom: 12px;
    font-size: 1.2rem;
    color: var(--dark);
}

.guide-step p {
    color: var(--gray);
    font-size: 0.95rem;
    line-height: 1.6;
}

.pro-tips {
    background: rgba(114, 9, 183, 0.05);
    border-left: 4px solid var(--accent);
    padding: 20px 25px;
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    margin-top: 40px;
}

.pro-tips h3 {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 15px;
    color: var(--accent);
}

.pro-tips ul {
    list-style-type: none;
    padding-left: 20px;
}

.pro-tips li {
    position: relative;
    padding-left: 25px;
    margin-bottom: 12px;
    line-height: 1.6;
    color: var(--dark);
}

.pro-tips li:before {
    content: "•";
    color: var(--accent);
    font-size: 1.4rem;
    position: absolute;
    left: 0;
    top: -3px;
}

@media (max-width: 768px) {
    .guide-steps {
        grid-template-columns: 1fr;
    }
    
    .pro-tips {
        padding: 15px;
    }
}

::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-track {
  background: var(--light-gray);
  border-radius: var(--border-radius);
  box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.05);
}

::-webkit-scrollbar-thumb {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: var(--border-radius);
  border: 2px solid var(--light);
  transition: var(--transition);
}

::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(135deg, var(--primary-dark), var(--accent));
  cursor: grab;
}

/* Firefox scrollbar */
* {
  scrollbar-width: thin;
  scrollbar-color: var(--primary) var(--light-gray);
}