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

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #2d3748;
    background: linear-gradient(135deg, #f6f8fa 0%, #ffffff 100%);
    min-height: 100vh;
}

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

.header {
    text-align: center;
    margin-bottom: 3rem;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #1a1a1a;
}

.subtitle {
    font-size: 1.1rem;
    color: #666;
    max-width: 800px;
    margin: 0 auto;
}

.converter-section {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 16px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    padding: 2.5rem;
    margin-bottom: 3rem;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.8);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.converter-section:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(0, 0, 0, 0.12);
}

.format-selection {
    margin-bottom: 2rem;
}

.format-group {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.format-dropdown {
    padding: 0.75rem 1.5rem;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 1rem;
    background-color: #ffffff;
    cursor: pointer;
    min-width: 120px;
    transition: all 0.2s ease;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%23718096' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.5rem center;
    background-size: 1.2em;
    padding-right: 2.5rem;
}

.format-dropdown:hover, .format-dropdown:focus {
    border-color: #4a5568;
    outline: none;
    box-shadow: 0 0 0 3px rgba(74, 85, 104, 0.1);
}

.to-text {
    font-size: 1rem;
    color: #666;
}

.upload-section {
    text-align: center;
    margin-bottom: 2rem;
}

.thumbnail-preview {
    margin-top: 1rem;
    text-align: center;
}

.thumbnail-preview img {
    max-width: 200px;
    max-height: 200px;
    border-radius: 4px;
    border: 2px solid #e0e0e0;
    object-fit: contain;
}

.btn {
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
    letter-spacing: 0.3px;
    position: relative;
    overflow: hidden;
}

.btn::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: width 0.6s ease, height 0.6s ease;
}

.btn:hover::after {
    width: 300%;
    height: 300%;
}

.btn-red {
    background: linear-gradient(135deg, #f5365c 0%, #dc3545 100%);
    box-shadow: 0 4px 15px rgba(220, 53, 69, 0.2);
}

.btn-red:hover {
    background: linear-gradient(135deg, #dc3545 0%, #c82333 100%);
    box-shadow: 0 6px 20px rgba(220, 53, 69, 0.3);
    transform: translateY(-1px);
}

.upload-button {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.upload-icon {
    font-size: 1.2rem;
}

.options-panel {
    border-top: 1px solid #e0e0e0;
    padding-top: 2rem;
    margin-top: 2rem;
}

.options-title {
    font-size: 1.2rem;
    font-weight: 500;
    margin-bottom: 1.5rem;
    color: #1a1a1a;
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.option-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.option-group label {
    font-size: 0.9rem;
    color: #666;
}

.option-group input[type="number"],
.option-group select {
    padding: 0.75rem;
    border: 1px solid #e0e0e0;
    border-radius: 4px;
    font-size: 1rem;
}

.checkbox-group {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 0.5rem;
}

.checkbox-group input[type="checkbox"] {
    width: 18px;
    height: 18px;
}

.convert-button {
    width: 100%;
}

.preview-section {
    margin-top: 2rem;
    text-align: center;
}

.preview-container {
    margin: 1rem 0;
    max-width: 100%;
    overflow: hidden;
}

.preview-container img {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
}

.btn-green {
    background: linear-gradient(135deg, #2dce89 0%, #28a745 100%);
    box-shadow: 0 4px 15px rgba(40, 167, 69, 0.2);
}

.btn-green:hover {
    background: linear-gradient(135deg, #28a745 0%, #218838 100%);
    box-shadow: 0 6px 20px rgba(40, 167, 69, 0.3);
    transform: translateY(-1px);
}

.how-it-works {
    text-align: center;
    padding: 3rem 0;
}

.how-it-works h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: #1a1a1a;
}

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

.step {
    padding: 1.5rem;
}

.step-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #f5365c 0%, #dc3545 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin: 0 auto 1rem;
    box-shadow: 0 4px 15px rgba(220, 53, 69, 0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.step:hover .step-icon {
    transform: translateY(-2px) scale(1.05);
    box-shadow: 0 6px 20px rgba(220, 53, 69, 0.3);
}

.step h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: #1a1a1a;
}

.step p {
    color: #666;
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

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

    .format-group {
        flex-direction: column;
    }

    .options-grid {
        grid-template-columns: 1fr;
    }

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