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

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-primary: #f9fafb;
    --bg-secondary: #ffffff;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 2rem 1rem;
    color: var(--text-primary);
}

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

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

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.subtitle {
    font-size: 1.125rem;
    opacity: 0.95;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: start;
}

.input-section,
.result-section {
    background: var(--bg-secondary);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow-xl);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.form-group textarea,
.form-group select,
.form-group input[type="number"] {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: all 0.3s ease;
    font-family: inherit;
}

.form-group textarea:focus,
.form-group select:focus,
.form-group input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.file-input-wrapper {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.file-input {
    display: none;
}

.file-label {
    flex: 1;
    display: inline-block;
    padding: 0.75rem 1rem;
    background: var(--bg-primary);
    border: 2px dashed var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
}

.file-label:hover {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.05);
}

.file-label span {
    color: var(--text-secondary);
}

.btn-clear {
    padding: 0.75rem 1rem;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.btn-clear:hover {
    background: #dc2626;
    transform: translateY(-1px);
}

.helper-text {
    display: block;
    margin-top: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-top: 1.5rem;
}

.form-group input[type="color"] {
    width: 100%;
    height: 45px;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.form-group input[type="color"]:hover {
    border-color: var(--primary-color);
}

.btn-generate {
    width: 100%;
    padding: 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 1rem;
}

.btn-generate:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.result-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    position: sticky;
    top: 2rem;
}

.qr-container {
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 300px;
    background: var(--bg-primary);
    border-radius: 0.75rem;
    padding: 2rem;
    position: relative;
}

.placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    color: var(--text-secondary);
}

.placeholder p {
    font-size: 0.875rem;
}

#qrcode {
    display: none;
}

#qrcode canvas {
    border-radius: 0.5rem;
    box-shadow: var(--shadow-md);
}

#qrCanvas {
    display: none;
}

.link-preview {
    width: 100%;
    margin-top: 1.5rem;
    padding: 1rem;
    background: var(--bg-primary);
    border-radius: 0.5rem;
    border-left: 4px solid var(--primary-color);
}

.link-preview strong {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.link-preview a {
    color: var(--primary-color);
    text-decoration: none;
    word-break: break-all;
    font-size: 0.95rem;
}

.link-preview a:hover {
    text-decoration: underline;
}

.action-buttons {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
    width: 100%;
}

.btn-download,
.btn-copy {
    flex: 1;
    padding: 0.875rem;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

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

.btn-download:hover {
    background: #059669;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-copy {
    background: var(--bg-primary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-copy:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    body {
        padding: 1rem;
    }

    header h1 {
        font-size: 2rem;
    }

    .main-content {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

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

    .result-section {
        position: static;
    }

    .action-buttons {
        flex-direction: column;
    }
}

/* 로딩 애니메이션 */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.loading {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

/* 성공 메시지 */
.success-message {
    position: fixed;
    top: 2rem;
    right: 2rem;
    background: var(--success-color);
    color: white;
    padding: 1rem 1.5rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-xl);
    animation: slideIn 0.3s ease;
    z-index: 1000;
    max-width: 90%;
    font-size: 0.95rem;
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}