/* 루트 변수 정의 - 노란색 테마 적용 */
:root {
    /* Primary Colors - 노란색 테마 */
    --primary-yellow: #FFC107;
    --primary-orange: #FF9800;
    --gradient-primary: linear-gradient(135deg, #FFD54F 0%, #FFAB00 100%);
    
    /* 기존 디자인 시스템 색상 (노란색 테마로 조정) */
    --primary-color: #FFC107;
    --primary-dark: #FFA000;
    --primary-light: #FFD54F;
    --primary-lighter: #FFE082;
    --primary-lightest: #FFF9C4;
    
    /* Secondary Colors */
    --secondary-color: #00bcd4;
    --secondary-dark: #00acc1;
    --secondary-light: #26c6da;
    
    /* Semantic Colors */
    --success-color: #4caf50;
    --success-light: #66bb6a;
    --warning-color: #ff9800;
    --warning-light: #ffa726;
    --danger-color: #f44336;
    --danger-light: #ef5350;
    --info-color: #2196f3;
    --info-light: #42a5f5;
    
    /* Background Colors - 밝은 톤 */
    --dark-bg: #FFFEF7;
    --card-bg: #ffffff;
    --card-hover: #FFF9E6;
    --input-bg: #ffffff;
    --modal-bg: rgba(255, 255, 255, 0.98);
    
    /* Text Colors */
    --text-primary: #212121;
    --text-secondary: #616161;
    --text-muted: #9e9e9e;
    --text-disabled: #bdbdbd;
    
    /* Border & Divider */
    --border-color: #e0e0e0;
    --border-light: #f5f5f5;
    --divider-color: rgba(0, 0, 0, 0.08);
    
    /* Enhanced Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.16), 0 2px 4px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
    --shadow-xl: 0 19px 38px rgba(0, 0, 0, 0.30), 0 15px 12px rgba(0, 0, 0, 0.22);
    --shadow-glow: 0 0 20px rgba(255, 193, 7, 0.4);
    
    /* Beautiful Gradients with yellow colors */
    --gradient-primary: linear-gradient(135deg, #FFD54F 0%, #FFAB00 100%);
    --gradient-secondary: linear-gradient(135deg, #00bcd4 0%, #26c6da 100%);
    --gradient-success: linear-gradient(135deg, #4caf50 0%, #66bb6a 100%);
    --gradient-warning: linear-gradient(135deg, #ff9800 0%, #ffa726 100%);
    --gradient-danger: linear-gradient(135deg, #f44336 0%, #ef5350 100%);
    --gradient-light: linear-gradient(180deg, #ffffff 0%, #f8f9fa 100%);
    
    /* Spacing System */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Animation Timing */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    --transition-slower: 500ms ease;
}

/* 리셋 및 기본 스타일 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(180deg, #FFFEF7 0%, #FFF9E6 100%);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    word-break: keep-all;
    word-wrap: break-word;
}

/* 컨테이너 */
.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* 헤더 */
.header {
    background: var(--gradient-primary);
    color: white;
    padding: 2rem 0;
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
    animation: slideDown 0.5s ease;
    text-align: center;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.header-content {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1rem 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.logo:hover {
    transform: scale(1.05);
}

.logo-icon {
    width: 56px;
    height: 56px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    padding: 6px;
    transition: all 0.3s ease;
}

.logo-icon:hover {
    background: rgba(255, 255, 255, 0.25);
    transform: rotate(-5deg) scale(1.05);
}

.logo-icon img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    filter: brightness(0) invert(1);
}

.logo-text h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: white;
}

.logo-text p {
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.9);
    font-weight: 500;
}

/* 네비게이션 메뉴 */
.nav-menu {
    display: flex;
    gap: 0.5rem;
}

.nav-btn {
    padding: 0.5rem 1.25rem;
    background: transparent;
    border: 1px solid transparent;
    color: rgba(255, 255, 255, 0.9);
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border-color: rgba(255, 255, 255, 0.3);
}

/* 히어로 섹션 */
.hero-section {
    padding: 4rem 0;
    text-align: center;
    animation: fadeInUp 0.8s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1rem;
    line-height: 1.2;
    color: var(--text-primary);
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* 검색 컨테이너 */
.search-container {
    position: relative;
    max-width: 600px;
    margin: 2rem auto;
}

.search-input {
    width: 100%;
    padding: 1rem 1rem 1rem 3rem;
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    border-radius: 16px;
    color: var(--text-primary);
    font-size: 1rem;
    transition: all 0.3s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(86, 54, 209, 0.1);
}

.search-icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
}

.search-suggestions {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    margin-top: 0.5rem;
    max-height: 300px;
    overflow-y: auto;
    display: none;
    box-shadow: var(--shadow-xl);
}

.search-suggestions.active {
    display: block;
}

.suggestion-item {
    padding: 0.75rem 1rem;
    cursor: pointer;
    transition: background 0.2s ease;
    border-bottom: 1px solid var(--border-color);
}

.suggestion-item:last-child {
    border-bottom: none;
}

.suggestion-item:hover {
    background: var(--card-hover);
}

/* 빠른 시작 버튼 */
.quick-start {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.quick-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    color: var(--text-primary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.quick-btn:hover {
    background: var(--card-hover);
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.quick-icon {
    font-size: 1.25rem;
}

/* 섹션 헤더 */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
}

/* 뷰 토글 */
.view-toggle {
    display: flex;
    gap: 0.25rem;
    background: var(--card-bg);
    border-radius: 8px;
    padding: 0.25rem;
    border: 1px solid var(--border-color);
}

.toggle-btn {
    padding: 0.5rem;
    background: transparent;
    border: none;
    border-radius: 6px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.toggle-btn.active {
    background: var(--gradient-primary);
    color: white;
}

/* 카테고리 그리드 */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.category-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.category-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.category-card:hover::before {
    transform: scaleX(1);
}

.category-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.category-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.category-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.15), rgba(255, 171, 0, 0.15));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.category-info {
    flex: 1;
}

.category-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.category-count {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.category-description {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-top: 0.5rem;
}

.category-arrow {
    color: var(--text-muted);
    transition: transform 0.3s ease;
}

.category-card:hover .category-arrow {
    transform: translateX(4px);
}

/* 계산기 리스트 */
.calculators-list {
    display: none;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    animation: slideDown 0.3s ease;
}

.category-card.expanded .calculators-list {
    display: block;
}

.calculator-item {
    padding: 0.75rem;
    margin: 0.5rem 0;
    background: var(--input-bg);
    border-radius: 8px;
    transition: all 0.2s ease;
    cursor: pointer;
    border: 1px solid transparent;
}

.calculator-item:hover {
    background: var(--card-hover);
    transform: translateX(4px);
    border-color: var(--primary-light);
}

/* 모달 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000;
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
}

.modal-content {
    position: relative;
    background: var(--card-bg);
    border-radius: 20px;
    max-width: 600px;
    width: 90%;
    max-height: 85vh;
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.08), rgba(255, 171, 0, 0.08));
}

.modal-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.modal-close {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    transition: all 0.2s ease;
    font-size: 1.5rem;
}

.modal-close:hover {
    background: var(--card-hover);
    color: var(--danger-color);
}

.modal-body {
    padding: 1.5rem;
    overflow-y: auto;
    max-height: calc(85vh - 80px);
}

/* 입력 그룹 */
.input-group {
    margin-bottom: 1.25rem;
}

.input-label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    font-size: 0.875rem;
    font-weight: 600;
}

.input-field {
    width: 100%;
    padding: 0.875rem 1rem;
    background: var(--input-bg);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    transition: all var(--transition-base);
}

/* 큰 입력 필드 */
.large-input {
    font-size: 17px;
    padding: 14px 45px 14px 18px;
    font-weight: 500;
    text-align: center;
    background: linear-gradient(to bottom, #ffffff, #fffef7);
    border: 2px solid var(--primary-light);
    height: 52px;
    letter-spacing: 0.5px;
}

.large-input:focus {
    border-color: #FFAB00;
    box-shadow: 0 0 0 4px rgba(255, 193, 7, 0.15), 0 4px 12px rgba(255, 193, 7, 0.2);
    transform: scale(1.025);
    background: linear-gradient(135deg, #FFFFFF 0%, #FFFDE7 100%);
}

/* 입력 래퍼 */
.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
    transition: transform 0.2s ease;
}

.input-wrapper:hover {
    transform: translateX(2px);
}

.input-suffix {
    position: absolute;
    right: 15px;
    color: #FF8F00;
    font-size: 15px;
    font-weight: 600;
    pointer-events: none;
    background: linear-gradient(135deg, #FFD54F 0%, #FFAB00 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.input-field:hover {
    border-color: var(--primary-light);
    background: var(--card-hover);
}

.input-field:focus {
    outline: none;
    border-color: var(--primary-color);
    background: var(--input-bg);
    box-shadow: 0 0 0 4px rgba(255, 193, 7, 0.15);
}

.input-field:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.input-field::placeholder {
    color: var(--text-muted);
}

select.input-field {
    cursor: pointer;
}

/* 버튼 */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
}

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

.btn-secondary {
    background: var(--card-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--card-hover);
    border-color: var(--primary-color);
}

.calculate-btn {
    width: 100%;
    max-width: 400px;
    padding: 1rem 1.5rem;
    background: var(--gradient-primary);
    border: none;
    border-radius: var(--radius-lg);
    color: white;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
    margin: var(--spacing-lg) auto 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

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

.calculate-btn:hover::before {
    width: 300px;
    height: 300px;
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow), var(--shadow-xl);
}

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

/* 결과 섹션 - 개선된 디자인 */
.result-section {
    margin-top: 2rem;
    padding: 2rem;
    background: linear-gradient(135deg, rgba(255, 249, 230, 0.5), rgba(255, 245, 225, 0.5));
    border: 1px solid rgba(255, 193, 7, 0.2);
    border-radius: var(--radius-xl);
    display: none;
    animation: slideUp 0.4s ease;
    position: relative;
    overflow: hidden;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.result-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--gradient-primary);
}

.result-section.active {
    display: block;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.result-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid rgba(255, 193, 7, 0.2);
}

.result-icon {
    width: 28px;
    height: 28px;
    background: linear-gradient(135deg, #FFD54F 0%, #FFAB00 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1rem;
    font-weight: bold;
    box-shadow: 0 2px 4px rgba(255, 193, 7, 0.2);
}

.result-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: #424242;
    letter-spacing: 0.3px;
}

.result-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(2, 1fr);
    align-items: start;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.875rem 1rem;
    background: #FFFFFF;
    border-radius: 8px;
    border: 1px solid #F5F5F5;
    transition: all 0.2s ease;
    min-height: 52px;
}

.result-item:hover {
    background: #FFFEF7;
    border-color: rgba(255, 193, 7, 0.2);
}

.result-label {
    font-size: 0.9rem;
    color: #666666;
    word-break: keep-all;
    font-weight: 500;
    letter-spacing: 0.3px;
}

.result-value {
    font-size: 1.35rem;
    font-weight: 700;
    color: #E65100;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    letter-spacing: -0.5px;
}

/* 도움말 및 설명 시스템 */
.calculator-description {
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background: linear-gradient(135deg, rgba(33, 150, 243, 0.05), rgba(0, 188, 212, 0.05));
    border-left: 3px solid var(--info-color);
    border-radius: var(--radius-md);
}

.calculator-description p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin: 0;
}

.calculator-description .formula {
    display: inline-block;
    padding: 0.125rem 0.375rem;
    background: rgba(33, 150, 243, 0.1);
    border-radius: var(--radius-sm);
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9rem;
    color: var(--info-color);
    margin: 0 0.25rem;
}

/* 도구 팁 */
.tooltip {
    position: relative;
    display: inline-block;
    cursor: help;
}

.tooltip-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    background: var(--gradient-primary);
    color: white;
    border-radius: 50%;
    font-size: 0.75rem;
    margin-left: 0.25rem;
}

.tooltip-content {
    visibility: hidden;
    width: 250px;
    background: var(--text-primary);
    color: white;
    text-align: left;
    border-radius: var(--radius-md);
    padding: var(--spacing-sm);
    position: absolute;
    z-index: 10;
    bottom: 125%;
    left: 50%;
    margin-left: -125px;
    opacity: 0;
    transition: opacity var(--transition-base);
    box-shadow: var(--shadow-lg);
    font-size: 0.875rem;
    line-height: 1.4;
}

.tooltip:hover .tooltip-content {
    visibility: visible;
    opacity: 1;
}

/* 입력 필드 그룹 개선 */
.input-row {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.input-with-icon {
    position: relative;
}

.input-icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    pointer-events: none;
}

.input-with-icon .input-field {
    padding-left: 2.5rem;
}

/* 라디오 버튼 및 체크박스 스타일 */
.radio-group,
.checkbox-group {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.radio-option,
.checkbox-option {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--input-bg);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-base);
}

.radio-option:hover,
.checkbox-option:hover {
    border-color: var(--primary-light);
    background: var(--card-hover);
}

.radio-option.selected,
.checkbox-option.selected {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.1), rgba(255, 171, 0, 0.1));
}

.radio-option input,
.checkbox-option input {
    margin: 0;
    cursor: pointer;
}

/* 에러 메시지 스타일 */
.error-message {
    display: none;
    padding: var(--spacing-md);
    background: linear-gradient(135deg, rgba(244, 67, 54, 0.1), rgba(239, 83, 80, 0.1));
    border: 1px solid var(--danger-color);
    border-radius: var(--radius-md);
    color: var(--danger-color);
    font-size: 0.9rem;
    margin-top: var(--spacing-md);
    animation: shake 0.5s ease;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

.error-message.active {
    display: block;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

/* 로딩 애니메이션 */
.loading-spinner {
    display: none;
    width: 40px;
    height: 40px;
    margin: var(--spacing-xl) auto;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.loading-spinner.active {
    display: block;
}

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

/* 테이블 스타일 */
.data-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: var(--spacing-md);
}

.data-table th,
.data-table td {
    padding: var(--spacing-sm) var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.data-table th {
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.08), rgba(255, 171, 0, 0.08));
    color: var(--text-primary);
    font-weight: 600;
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.data-table td {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.data-table tr:hover td {
    background: var(--card-hover);
}

/* 차트 컨테이너 */
.chart-container {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-lg);
    background: var(--input-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.chart-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

/* 액션 버튼 그룹 */
.action-buttons {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
    flex-wrap: wrap;
}

.action-btn {
    flex: 1;
    min-width: 120px;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-base);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.action-btn:hover {
    background: var(--card-hover);
    border-color: var(--primary-light);
    color: var(--text-primary);
}

.action-btn.primary {
    background: var(--gradient-primary);
    border-color: transparent;
    color: white;
}

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

/* 토스트 알림 */
.result-toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--card-bg);
    border: 1px solid var(--success-color);
    border-radius: 12px;
    padding: 1rem 1.5rem;
    box-shadow: var(--shadow-xl);
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
}

.result-toast.active {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast-content {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.toast-icon {
    font-size: 1.25rem;
}

.toast-message {
    font-size: 0.9rem;
    color: var(--text-primary);
}

/* 로딩 오버레이 */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 2000;
}

.loading-overlay.active {
    display: flex;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

/* 푸터 */
.footer {
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.05), rgba(255, 171, 0, 0.05));
    border-top: 1px solid var(--border-color);
    margin-top: 4rem;
    padding: 2rem 0;
    text-align: center;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.footer-section h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.footer-section p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    transition: color 0.2s ease;
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-bottom p {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .categories-grid {
        grid-template-columns: 1fr;
    }
    
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-menu {
        width: 100%;
        justify-content: center;
    }
    
    .quick-start {
        flex-direction: column;
    }
    
    .quick-btn {
        width: 100%;
    }
    
    .modal-content {
        width: 95%;
        max-height: 90vh;
    }
}

/* 유틸리티 클래스 */
.text-center {
    text-align: center;
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }
.gap-4 { gap: 2rem; }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }

.hidden { display: none !important; }
.visible { display: block !important; }

/* 메인 컨텐츠 */
.main-content {
    padding: 2rem 0;
    min-height: calc(100vh - 200px);
}

/* 초기 환영 화면 */
.welcome-screen {
    padding: 3rem 0;
    animation: fadeInUp 0.6s ease;
}

.welcome-content {
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.welcome-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.welcome-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    word-break: keep-all;
}

/* 계산기 선택 카드 */
.calculator-selection {
    display: flex;
    justify-content: center;
    align-items: stretch;
    gap: 2rem;
    margin-top: 2rem;
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
    min-height: 500px;
}

.calculator-option {
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    border-radius: 20px;
    padding: 2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    flex: 1;
    max-width: 400px;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    justify-content: space-between;
}

.calculator-option::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.calculator-option:hover::before {
    transform: scaleX(1);
}

.calculator-option:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-light);
}

.option-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 1.5rem;
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.15), rgba(255, 171, 0, 0.15));
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    padding: 15px;
    position: relative;
    overflow: hidden;
}

.option-icon img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    filter: hue-rotate(0deg) saturate(1.2);
    transition: all 0.3s ease;
}

.calculator-option:hover .option-icon img {
    transform: scale(1.1);
    filter: hue-rotate(10deg) saturate(1.5);
}

.option-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.option-description {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 1.5rem;
    word-break: keep-all;
    flex-grow: 1;
    display: flex;
    align-items: center;
}

.option-features {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    justify-content: center;
    width: 100%;
    min-height: 40px;
    align-items: center;
}

.feature-tag {
    padding: 0.25rem 0.75rem;
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.1), rgba(255, 171, 0, 0.1));
    border: 1px solid var(--primary-light);
    border-radius: 20px;
    font-size: 0.875rem;
    color: var(--primary-color);
    white-space: nowrap;
}

.option-button {
    width: 100%;
    padding: 0.875rem 1.5rem;
    background: var(--gradient-primary);
    border: none;
    border-radius: 12px;
    color: white;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-top: auto;
}

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

/* 계산기 영역 */
.calculator-area {
    animation: fadeIn 0.5s ease;
}

.calculator-area.hidden {
    display: none;
}

/* 계산기 선택기 */
.calculator-selector {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
    position: relative;
}

.back-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 1rem;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    position: absolute;
    left: 0;
}

.back-btn:hover {
    background: var(--card-hover);
    border-color: var(--primary-light);
    color: var(--text-primary);
}

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

.selector-btn {
    padding: 0.625rem 1.5rem;
    background: transparent;
    border: 2px solid transparent;
    border-radius: 10px;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
}

.selector-btn::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 3px;
    background: var(--gradient-primary);
    transition: width 0.3s ease;
}

.selector-btn:hover {
    color: var(--primary-color);
}

.selector-btn.active {
    color: var(--primary-color);
    background: linear-gradient(135deg, rgba(255, 213, 79, 0.1), rgba(255, 171, 0, 0.1));
    border-color: var(--primary-light);
}

.selector-btn.active::after {
    width: 80%;
}

/* 계산기 카드 개선 */
.calculator-card {
    background: var(--card-bg);
    border-radius: 20px;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    animation: fadeIn 0.5s ease;
    max-width: 900px;
    margin: 0 auto;
}

.card-header {
    text-align: center;
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 2px solid var(--border-light);
    position: relative;
}

.card-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.card-description {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.6;
    word-break: keep-all;
}

/* 정보 박스 */
.info-box {
    background: linear-gradient(135deg, rgba(33, 150, 243, 0.05), rgba(0, 188, 212, 0.05));
    border-left: 3px solid var(--info-color);
    border-radius: 10px;
    padding: 1rem;
    margin-bottom: 1.5rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* 도움말 버튼 */
.help-btn {
    position: absolute;
    top: 0;
    right: 0;
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, #FFF9E6 0%, #FFECB3 100%);
    border: 2px solid #FFD54F;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    color: #FF6F00;
    font-weight: bold;
    font-size: 18px;
    box-shadow: 0 2px 4px rgba(255, 193, 7, 0.2);
    font-style: normal;
}

.help-btn:hover {
    background: linear-gradient(135deg, #FFECB3 0%, #FFD54F 100%);
    border-color: #FFAB00;
    color: #E65100;
    transform: scale(1.15);
    box-shadow: 0 4px 8px rgba(255, 193, 7, 0.3);
}

/* 도움말 컨텐츠 */
.help-content {
    display: none;
    background: linear-gradient(135deg, rgba(255, 249, 230, 0.9) 0%, rgba(255, 245, 225, 0.9) 100%);
    border: 2px solid rgba(255, 193, 7, 0.3);
    border-radius: 16px;
    padding: 25px;
    margin-bottom: 2rem;
    margin-top: 20px;
    box-shadow: inset 0 2px 8px rgba(255, 193, 7, 0.1);
    animation: slideDownHelp 0.4s ease;
}

.help-content.active {
    display: block;
}

@keyframes slideDownHelp {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.help-section {
    margin-bottom: 1.5rem;
}

.help-section:last-child {
    margin-bottom: 0;
}

.help-section h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
}

.help-section p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    word-break: keep-all;
}

.formula-box {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.9) 0%, rgba(255, 253, 231, 0.9) 100%);
    border: 2px solid rgba(255, 193, 7, 0.3);
    border-radius: 12px;
    padding: 18px;
    margin: 15px 0;
    box-shadow: 0 2px 6px rgba(255, 193, 7, 0.1);
    position: relative;
    overflow: hidden;
}

.formula-box::before {
    content: '📐';
    position: absolute;
    top: 10px;
    right: 10px;
    font-size: 20px;
    opacity: 0.5;
}

.formula-box p {
    margin: 0.5rem 0;
    font-family: 'JetBrains Mono', 'Monaco', 'Courier New', monospace;
    font-size: 15px;
}

.formula-note {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 0.75rem;
    line-height: 1.8;
}

.help-list {
    margin: 0;
    padding-left: 1.5rem;
}

.help-list li {
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}


.info-box p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin: 0;
    word-break: keep-all;
}

.info-box .formula {
    display: inline-block;
    padding: 0.125rem 0.375rem;
    background: rgba(33, 150, 243, 0.1);
    border-radius: 4px;
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9rem;
    color: var(--info-color);
    margin: 0 0.25rem;
}

/* 입력 섹션 개선 */
.input-section {
    margin-bottom: 2rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.section-subtitle {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-light);
    text-align: center;
}

.label-hint {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 400;
    margin-top: 0.25rem;
    word-break: keep-all;
}


/* 숫자 선택기 */
.number-selector {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.number-btn {
    width: 36px;
    height: 36px;
    background: var(--gradient-primary);
    border: none;
    border-radius: 8px;
    color: white;
    font-size: 1.25rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.number-btn:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-md);
}

.number-btn:active {
    transform: scale(0.95);
}

.number-selector .input-field {
    width: 80px;
    text-align: center;
    font-weight: 600;
}

/* input number 타입의 기본 스피너 제거 */
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"] {
    -moz-appearance: textfield;
}

/* 로딩 필드 그리드 */
.loading-fields-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

/* 결과 아이템 하이라이트 */
.result-item.highlight {
    background: transparent;
    border: none;
    padding: 0;
}

.result-item.highlight:hover {
    transform: none;
    box-shadow: none;
}


/* 유의성/수렴타당도 중앙 디스플레이 */
.significance-display {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 2.5rem auto;
    padding: 1.5rem;
    width: 100%;
    text-align: center;
}

.significance-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: #E65100;
    text-align: center;
    display: inline-block;
    line-height: 1.4;
    padding: 1rem 2rem;
    background: rgba(255, 249, 230, 0.3);
    border-radius: 12px;
    letter-spacing: -0.3px;
    transition: all 0.3s ease;
}

.significance-value:hover {
    background: rgba(255, 249, 230, 0.5);
    transform: translateY(-2px);
}


/* 반응형 개선 */
@media (max-width: 768px) {
    .calculator-selection {
        flex-direction: column;
        align-items: center;
    }
    
    .calculator-option {
        max-width: 100%;
        width: 100%;
    }
    
    .input-row {
        grid-template-columns: 1fr;
    }
    
    .calculator-option {
        padding: 1.5rem;
    }
    
    .option-icon {
        width: 60px;
        height: 60px;
    }
    
    .selector-tabs {
        flex-direction: column;
        width: 100%;
    }
    
    .selector-btn {
        width: 100%;
    }
    
    .calculator-selector {
        flex-direction: column;
        align-items: stretch;
    }
    
    .back-btn {
        width: 100%;
        justify-content: center;
    }
    
    .loading-fields-grid {
        grid-template-columns: 1fr;
    }
}