:root {
    --primary-color: #4a90e2;
    --secondary-color: #f5f6fa;
    --text-color: #2c3e50;
    --border-color: #dcdde1;
    --success-color: #2ecc71;
    --error-color: #e74c3c;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: #f0f2f5;
}

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

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

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.upload-section {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.file-input-group {
    margin-bottom: 1.5rem;
}

.file-input-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

input[type="file"] {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 5px;
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1rem;
    border-radius: 5px;
    cursor: pointer;
    width: 100%;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #357abd;
}

.hidden {
    display: none;
}

#loading {
    text-align: center;
    margin-top: 1rem;
}

.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

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

.result-item {
    background: white;
    padding: 1.5rem;
    border-radius: 10px;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.diff-images {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
}

.diff-image-card {
    border: 1px solid var(--border-color);
    border-radius: 5px;
    overflow: hidden;
}

.diff-image-card img {
    width: 100%;
    height: auto;
    display: block;
    cursor: pointer;
}

.diff-image-card p {
    padding: 0.5rem;
    text-align: center;
    background: var(--secondary-color);
    font-size: 0.9rem;
}

/* 모달 스타일 (이미지 확대 보기용) */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.9);
}

.modal-content {
    margin: auto;
    display: block;
    max-width: 90%;
    max-height: 90vh;
    position: relative;
    top: 50%;
    transform: translateY(-50%);
}

.close {
    position: absolute;
    top: 15px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
}