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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 40px 20px;
}

.header {
    text-align: center;
    margin-bottom: 60px;
    opacity: 0;
    animation: fadeInUp 0.8s ease-out 0.2s forwards;
}

.header h1 {
    font-size: 3rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
}

.header p {
    font-size: 1.1rem;
    color: #7f8c8d;
    font-weight: 300;
}

/* 플랫폼 선택기 */
.platform-selector {
    margin-top: 30px;
    text-align: center;
}

.platform-selector h3 {
    color: #2c3e50;
    font-size: 1.2rem;
    margin-bottom: 20px;
    font-weight: 500;
}

.platform-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
    max-width: 1000px;
    margin: 0 auto;
}

.platform-btn {
    background: white;
    border: 2px solid #e3f2fd;
    border-radius: 15px;
    padding: 15px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    min-height: 120px;
    justify-content: center;
}

.platform-btn:hover {
    border-color: #3aa6ff;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(58, 166, 255, 0.2);
}

.platform-btn.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background: #f8f9fa;
    border-color: #e9ecef;
}

.platform-btn.disabled:hover {
    transform: none;
    box-shadow: none;
    border-color: #e9ecef;
}

.platform-btn.disabled .platform-desc {
    color: #6c757d;
    font-weight: 500;
}

.platform-btn.active {
    border-color: #3aa6ff;
    background: #f0f8ff;
    box-shadow: 0 4px 15px rgba(58, 166, 255, 0.3);
}

.platform-icon {
    font-size: 1.8rem;
}

.platform-name {
    font-size: 0.95rem;
    font-weight: 600;
    color: #2c3e50;
    text-align: center;
}

.platform-desc {
    font-size: 0.8rem;
    color: #7f8c8d;
    text-align: center;
}

.step {
    margin-bottom: 80px;
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease-out;
}

.step.visible {
    opacity: 1;
    transform: translateY(0);
}

.step-card {
    background: white;
    border-radius: 20px;
    padding: 60px 40px 40px 40px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    text-align: center;
    position: relative;
    overflow: visible;
}

.step-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #3aa6ff, #00d4ff);
}

.step-number {
    position: absolute;
    top: -25px;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 50px;
    background: #3aa6ff;
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 1.4rem;
    box-shadow: 0 4px 15px rgba(58, 166, 255, 0.3);
    z-index: 10;
}

.step h2 {
    font-size: 2rem;
    font-weight: 500;
    color: #2c3e50;
    margin-bottom: 15px;
    margin-top: 20px;
}

.step p {
    color: #7f8c8d;
    font-size: 1rem;
    margin-bottom: 30px;
}

/* 업로드 영역 */
.upload-area {
    border: 2px dashed #ddd;
    border-radius: 15px;
    padding: 60px 20px;
    transition: all 0.3s ease;
    cursor: pointer;
    background: #fafbfc;
}

.upload-area:hover {
    border-color: #3aa6ff;
    background: #f8fcff;
    transform: translateY(-2px);
}

.upload-area.dragover {
    border-color: #3aa6ff;
    background: #f0f8ff;
    transform: scale(1.02);
}

.upload-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.upload-icon {
    font-size: 3rem;
    opacity: 0.6;
}

.upload-content p {
    color: #7f8c8d;
    font-size: 1.1rem;
    margin: 0;
}

/* 업로드 팁 */
.upload-tip {
    background: #f8fcff;
    border: 1px solid #e3f2fd;
    border-radius: 12px;
    padding: 20px;
    margin: 20px 0;
    text-align: left;
}

.upload-tip p {
    margin: 8px 0;
    color: #2c3e50;
    font-size: 0.95rem;
    line-height: 1.5;
}

.upload-tip p:first-child {
    margin-top: 0;
    color: #3aa6ff;
    font-size: 1rem;
}

.upload-tip p:nth-child(2) {
    color: #27ae60;
    font-weight: 500;
    font-size: 1rem;
}

.upload-tip p:nth-child(3) {
    color: #3aa6ff;
    font-weight: 500;
    font-size: 1rem;
}

/* 파일 정보 */
.file-info {
    background: #f8f9fa;
    border: 1px solid #e9ecef;
    border-radius: 10px;
    padding: 15px;
    margin-bottom: 20px;
    text-align: left;
    font-size: 0.9rem;
}

.file-info p {
    margin: 5px 0;
    color: #2c3e50;
}

.file-info p:first-child {
    margin-top: 0;
    color: #3aa6ff;
    font-weight: 500;
}

.upload-tip p:last-child {
    margin-bottom: 0;
}

/* 미리보기 영역 */
.preview-area {
    margin-top: 30px;
    padding: 30px;
    background: #f8fcff;
    border-radius: 15px;
    border: 1px solid #e3f2fd;
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.preview-area h3 {
    color: #2c3e50;
    margin: 0;
    font-size: 1.3rem;
}

.btn-delete {
    background: #e74c3c;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 8px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-delete:hover {
    background: #c0392b;
    transform: translateY(-1px);
}

.preview-container {
    margin-bottom: 25px;
}

.preview-container img {
    max-width: 300px;
    max-height: 300px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}


/* 리사이즈 섹션 */
.resize-section {
    margin-top: 30px;
    padding: 25px;
    background: #f0f8ff;
    border-radius: 15px;
    border: 1px solid #e3f2fd;
}

.resize-section h3 {
    color: #2c3e50;
    margin-bottom: 10px;
    font-size: 1.2rem;
}

.resize-section p {
    color: #7f8c8d;
    font-size: 0.95rem;
    margin-bottom: 20px;
}

.resize-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
    align-items: start;
}

.resize-item {
    background: white;
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.resize-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.resize-item img {
    border-radius: 6px;
    border: 1px solid #e3f2fd;
    image-rendering: pixelated; /* 픽셀 아트 스타일 렌더링 */
    image-rendering: -moz-crisp-edges;
    image-rendering: crisp-edges;
}

.resize-item .size-label {
    font-size: 0.85rem;
    color: #3aa6ff;
    font-weight: 500;
    margin: 0;
}

.resize-item .size-info {
    font-size: 0.75rem;
    color: #7f8c8d;
    margin: 2px 0 0 0;
}

.resize-item .size-usage {
    font-size: 0.7rem;
    color: #95a5a6;
    margin: 2px 0 0 0;
    font-style: italic;
}

.btn-small {
    padding: 8px 16px;
    font-size: 0.8rem;
    margin-top: 8px;
}

/* 변환 영역 */
.conversion-area {
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3aa6ff;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.download-area {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.converted-icons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 15px;
    margin: 20px 0;
    max-width: 600px;
    width: 100%;
}

.converted-icon-item {
    background: white;
    border-radius: 10px;
    padding: 15px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    position: relative;
}

.converted-icon-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.converted-icon-item img {
    border-radius: 6px;
    border: 1px solid #e3f2fd;
    image-rendering: pixelated;
    image-rendering: -moz-crisp-edges;
    image-rendering: crisp-edges;
}

.converted-icon-item .size-label {
    font-size: 0.8rem;
    color: #3aa6ff;
    font-weight: 500;
    margin: 0;
}

.converted-icon-item .size-info {
    font-size: 0.7rem;
    color: #7f8c8d;
    margin: 0;
}

.icon-checkbox {
    position: absolute;
    top: 8px;
    right: 8px;
    z-index: 10;
}

.icon-check {
    width: 18px;
    height: 18px;
    accent-color: #3aa6ff;
    cursor: pointer;
}

.download-actions {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin-top: 20px;
    align-items: center;
}

.btn-highlight {
    background: linear-gradient(135deg, #ff6b6b, #ff8e53);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
    position: relative;
    overflow: hidden;
}

.btn-highlight:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 107, 107, 0.4);
    background: linear-gradient(135deg, #ff5252, #ff7043);
}

.btn-highlight:active {
    transform: translateY(0);
}

.btn-highlight::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn-highlight:hover::before {
    left: 100%;
}

.success-icon {
    font-size: 3rem;
}

.download-area h3 {
    color: #27ae60;
    font-size: 1.5rem;
    margin: 0;
}

/* 병합 영역 */
.merge-area {
    text-align: left;
}

.ico-list {
    min-height: 150px;
    border: 2px dashed #ddd;
    border-radius: 15px;
    padding: 30px;
    margin-bottom: 30px;
    background: #fafbfc;
}

.empty-message {
    text-align: center;
    color: #7f8c8d;
    font-style: italic;
    margin: 0;
}

.ico-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 15px;
    background: white;
    border-radius: 10px;
    margin-bottom: 10px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    animation: slideIn 0.3s ease-out;
}

.ico-item:last-child {
    margin-bottom: 0;
}

.merged-icon-item {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 20px;
    background: linear-gradient(135deg, #f8fcff, #e3f2fd);
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    margin-bottom: 20px;
    border: 2px solid #3aa6ff;
}

.icon-preview {
    flex-shrink: 0;
}

.icon-info {
    flex: 1;
}

.icon-info h4 {
    margin: 0 0 5px 0;
    color: #2c3e50;
    font-size: 1.1rem;
}

.icon-info p {
    margin: 0;
    color: #7f8c8d;
    font-size: 0.9rem;
}

.platform-info {
    color: #3aa6ff !important;
    font-weight: 600;
    margin-top: 5px !important;
}

.merge-area {
    margin-top: 20px;
}

.ico-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

.ico-icon {
    width: 32px;
    height: 32px;
    background: #3aa6ff;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.2rem;
}

.ico-details h4 {
    color: #2c3e50;
    font-size: 1rem;
    margin: 0 0 5px 0;
}

.ico-details p {
    color: #7f8c8d;
    font-size: 0.9rem;
    margin: 0;
}

.remove-btn {
    background: #e74c3c;
    color: white;
    border: none;
    border-radius: 6px;
    padding: 8px 12px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s ease;
}

.remove-btn:hover {
    background: #c0392b;
    transform: scale(1.05);
}

/* 버튼 스타일 */
.btn {
    padding: 15px 30px;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
    font-family: inherit;
}

.btn-primary {
    background: #3aa6ff;
    color: white;
    box-shadow: 0 4px 15px rgba(58, 166, 255, 0.3);
}

.btn-primary:hover {
    background: #2980b9;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(58, 166, 255, 0.4);
}

.btn-secondary {
    background: #ecf0f1;
    color: #2c3e50;
    border: 1px solid #bdc3c7;
}

.btn-secondary:hover {
    background: #d5dbdb;
    transform: translateY(-1px);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
}

/* 애니메이션 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.9);
    border-top: 1px solid #e3f2fd;
    margin-top: 60px;
    padding: 30px 0;
    text-align: center;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}

.footer-content p {
    margin: 5px 0;
    color: #7f8c8d;
    font-size: 0.9rem;
}

.footer-content a {
    color: #3aa6ff;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-content a:hover {
    color: #2980b9;
    text-decoration: underline;
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .container {
        padding: 20px 15px;
    }
    
    .header h1 {
        font-size: 2.5rem;
    }
    
    .platform-buttons {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    
    .platform-btn {
        padding: 12px;
        min-height: 100px;
    }
    
    .platform-icon {
        font-size: 1.5rem;
    }
    
    .platform-name {
        font-size: 0.9rem;
    }
    
    .platform-desc {
        font-size: 0.75rem;
    }
    
    .step-card {
        padding: 30px 20px;
    }
    
    .step h2 {
        font-size: 1.5rem;
    }
    
    .upload-area {
        padding: 40px 15px;
    }
    
    .btn {
        padding: 12px 24px;
        font-size: 0.95rem;
    }
}