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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #e3f2fd 0%, #f3e5f5 100%);
    min-height: 100vh;
    color: #333;
}

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

/* Header */
header {
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    padding: 15px 0;
    margin-bottom: 40px;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 20px;
    font-weight: 600;
}

.logo-icon {
    width: 35px;
    height: 35px;
    background: #2196F3;
    color: white;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

nav {
    display: flex;
    gap: 30px;
}

.nav-link {
    text-decoration: none;
    color: #666;
    font-weight: 500;
    font-size: 14px;
    padding: 8px 0;
    border-bottom: 2px solid transparent;
    transition: all 0.3s;
}

.nav-link.active {
    color: #2196F3;
    border-bottom-color: #2196F3;
}

.nav-link:hover {
    color: #2196F3;
}

.btn-login {
    background: white;
    border: 2px solid #2196F3;
    color: #2196F3;
    padding: 8px 25px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-login:hover {
    background: #2196F3;
    color: white;
}

/* Main Content */
h1 {
    text-align: center;
    font-size: 42px;
    margin-bottom: 40px;
    color: #1a1a1a;
    font-weight: 700;
}

/* Tabs */
.tabs {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.tab {
    background: white;
    border: none;
    padding: 12px 25px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 15px;
    transition: all 0.3s;
    color: #666;
    font-weight: 500;
}

.tab.active {
    background: #e3f2fd;
    color: #2196F3;
    font-weight: 600;
}

.tab:hover {
    background: #e3f2fd;
    color: #2196F3;
}

/* Upload Section */
.upload-section {
    margin-bottom: 50px;
}

.upload-box {
    background: white;
    border: 3px dashed #ccc;
    border-radius: 15px;
    padding: 60px 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    position: relative;
}

.upload-box:hover {
    border-color: #2196F3;
    background: #f8fbff;
}

.upload-box.dragover {
    border-color: #2196F3;
    background: #e3f2fd;
}

.upload-icon {
    font-size: 60px;
    margin-bottom: 15px;
}

.upload-box h3 {
    font-size: 22px;
    margin-bottom: 8px;
    color: #333;
}

.upload-box p {
    color: #999;
    font-size: 15px;
}

#fileInput {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
}

.file-info {
    margin-top: 20px;
    color: #2196F3;
    font-weight: 600;
}

/* Converter Grid */
.converter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 50px;
}

.converter-card {
    background: white;
    border-radius: 15px;
    padding: 35px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    position: relative;
    overflow: hidden;
}

.converter-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(33, 150, 243, 0.1), rgba(33, 150, 243, 0));
    opacity: 0;
    transition: opacity 0.3s;
}

.converter-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(33, 150, 243, 0.2);
}

.converter-card:hover::before {
    opacity: 1;
}

.converter-card.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.card-icon {
    font-size: 45px;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 60px;
}

.converter-card h3 {
    font-size: 16px;
    color: #333;
    font-weight: 600;
}

/* Processing Area */
.processing-area {
    background: white;
    border-radius: 15px;
    padding: 40px;
    text-align: center;
    margin: 30px 0;
}

.processing-area h2 {
    margin-bottom: 25px;
    color: #333;
}

.progress-bar {
    width: 100%;
    height: 30px;
    background: #f0f0f0;
    border-radius: 15px;
    overflow: hidden;
    margin-bottom: 15px;
}

.progress {
    height: 100%;
    background: linear-gradient(90deg, #2196F3, #64B5F6);
    width: 0%;
    transition: width 0.3s;
    border-radius: 15px;
}

#statusText {
    color: #666;
    font-size: 15px;
}

/* Result Area */
.result-area {
    background: white;
    border-radius: 15px;
    padding: 40px;
    text-align: center;
}

.result-area h2 {
    color: #4CAF50;
    margin-bottom: 25px;
}

.btn-download, .btn-new {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    margin: 10px;
    transition: all 0.3s;
}

.btn-download {
    background: #2196F3;
    color: white;
}

.btn-download:hover {
    background: #1976D2;
    transform: scale(1.05);
}

.btn-new {
    background: #f5f5f5;
    color: #333;
}

.btn-new:hover {
    background: #e0e0e0;
}

/* Responsive */
@media (max-width: 768px) {
    h1 {
        font-size: 28px;
    }
    
    nav {
        display: none;
    }
    
    .converter-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
        gap: 15px;
    }
    
    .converter-card {
        padding: 25px 15px;
    }
    
    .card-icon {
        font-size: 35px;
        height: 50px;
    }
}