/* =================================== 
   무게 변환기 스타일
   =================================== */

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

:root {
    --primary-color: #4A90E2;
    --secondary-color: #50C878;
    --accent-color: #9B59B6;
    --dark-color: #2C3E50;
    --light-bg: #F8F9FA;
    --white: #FFFFFF;
    --border-color: #E0E0E0;
    --text-color: #333333;
    --text-light: #666666;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --shadow-hover: 0 5px 20px rgba(0,0,0,0.15);
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.header {
    background-color: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}

.logo {
    font-size: 24px;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s;
}

.logo:hover {
    color: var(--secondary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 25px;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s;
}

.nav-menu a.active {
    color: var(--primary-color);
    font-weight: 600;
}

.nav-menu a:hover {
    color: var(--primary-color);
}

/* Main Content */
.main {
    padding: 40px 0;
}

/* Hero Section */
.hero-section {
    text-align: center;
    padding: 60px 0;
}

.hero-section h1 {
    font-size: 48px;
    color: var(--dark-color);
    margin-bottom: 15px;
    font-weight: 700;
}

.subtitle {
    font-size: 20px;
    color: var(--text-light);
    margin-bottom: 50px;
}

/* Converter Box */
.converter-box {
    max-width: 800px;
    margin: 0 auto;
    background-color: var(--white);
    padding: 40px;
    border-radius: 16px;
    box-shadow: var(--shadow);
}

.input-section,
.output-section {
    margin-bottom: 30px;
}

.input-section label,
.output-section label {
    display: block;
    font-size: 16px;
    font-weight: 600;
    color: var(--dark-color);
    margin-bottom: 10px;
}

.input-group,
.output-group {
    display: flex;
    gap: 15px;
}

.input-group input,
.output-group input {
    flex: 1;
    padding: 18px 25px;
    font-size: 20px;
    font-weight: 600;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    transition: border-color 0.3s;
}

.input-group input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.output-group input {
    background-color: var(--light-bg);
    color: var(--primary-color);
}

.unit-select {
    padding: 18px 20px;
    font-size: 16px;
    font-weight: 500;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    background-color: var(--white);
    cursor: pointer;
    transition: border-color 0.3s;
    min-width: 180px;
}

.unit-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Convert Arrow */
.convert-arrow {
    text-align: center;
    margin: 20px 0;
}

.swap-btn {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color), #357ABD);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 24px;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
}

.swap-btn:hover {
    transform: rotate(180deg) scale(1.1);
    box-shadow: 0 6px 20px rgba(74, 144, 226, 0.4);
}

/* Quick Convert Buttons */
.quick-convert {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    margin-top: 30px;
    padding-top: 30px;
    border-top: 2px solid var(--light-bg);
}

.quick-btn {
    flex: 1;
    min-width: 100px;
    padding: 12px 20px;
    background-color: var(--light-bg);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.3s;
}

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

/* Conversion Table Section */
.conversion-table-section {
    padding: 80px 0;
    background-color: var(--white);
}

.conversion-table-section h2 {
    font-size: 36px;
    text-align: center;
    color: var(--dark-color);
    margin-bottom: 40px;
    font-weight: 700;
}

.table-container {
    overflow-x: auto;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.conversion-table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--white);
}

.conversion-table thead {
    background: linear-gradient(135deg, var(--primary-color), #357ABD);
    color: white;
}

.conversion-table th,
.conversion-table td {
    padding: 18px 20px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.conversion-table th {
    font-weight: 600;
    font-size: 16px;
}

.conversion-table td {
    font-size: 15px;
}

.conversion-table tbody tr:hover {
    background-color: var(--light-bg);
}

.conversion-table tbody tr:last-child td {
    border-bottom: none;
}

/* Features Section */
.features-section {
    padding: 80px 0;
}

.features-section h2 {
    font-size: 36px;
    text-align: center;
    color: var(--dark-color);
    margin-bottom: 50px;
    font-weight: 700;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.feature-card {
    background-color: var(--white);
    padding: 40px 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
}

.feature-icon {
    font-size: 56px;
    margin-bottom: 20px;
}

.feature-card h3 {
    font-size: 22px;
    color: var(--dark-color);
    margin-bottom: 15px;
    font-weight: 600;
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.7;
    font-size: 15px;
}

/* Usage Guide */
.usage-guide {
    padding: 80px 0;
    background-color: var(--white);
}

.usage-guide h2 {
    font-size: 36px;
    text-align: center;
    color: var(--dark-color);
    margin-bottom: 50px;
    font-weight: 700;
}

.guide-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    max-width: 1000px;
    margin: 0 auto;
}

.guide-card {
    background-color: var(--light-bg);
    padding: 30px;
    border-radius: 12px;
    text-align: center;
    position: relative;
    transition: transform 0.3s;
}

.guide-card:hover {
    transform: translateY(-5px);
}

.guide-number {
    position: absolute;
    top: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), #357ABD);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 20px;
    box-shadow: 0 4px 10px rgba(74, 144, 226, 0.3);
}

.guide-card h3 {
    font-size: 20px;
    color: var(--dark-color);
    margin: 20px 0 12px;
    font-weight: 600;
}

.guide-card p {
    color: var(--text-light);
    line-height: 1.7;
}

/* FAQ Section */
.faq-section {
    padding: 80px 0;
}

.faq-section h2 {
    font-size: 36px;
    text-align: center;
    color: var(--dark-color);
    margin-bottom: 50px;
    font-weight: 700;
}

.faq-list {
    max-width: 900px;
    margin: 0 auto;
    background-color: var(--white);
    padding: 40px;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.faq-item {
    margin-bottom: 30px;
    padding-bottom: 30px;
    border-bottom: 1px solid var(--border-color);
}

.faq-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.faq-item h3 {
    font-size: 18px;
    color: var(--dark-color);
    margin-bottom: 12px;
    font-weight: 600;
}

.faq-item p {
    color: var(--text-light);
    line-height: 1.8;
    font-size: 15px;
}

/* Footer */
.footer {
    background-color: var(--dark-color);
    color: var(--white);
    text-align: center;
    padding: 25px 0;
    margin-top: 40px;
}

/* Responsive */
@media (max-width: 768px) {
    .nav {
        flex-direction: column;
        gap: 15px;
    }

    .nav-menu {
        flex-wrap: wrap;
        justify-content: center;
        gap: 15px;
    }

    .hero-section h1 {
        font-size: 32px;
    }

    .subtitle {
        font-size: 16px;
    }

    .converter-box {
        padding: 25px;
    }

    .input-group,
    .output-group {
        flex-direction: column;
    }

    .unit-select {
        width: 100%;
    }

    .quick-convert {
        flex-direction: column;
    }

    .quick-btn {
        width: 100%;
    }

    .conversion-table {
        font-size: 14px;
    }

    .conversion-table th,
    .conversion-table td {
        padding: 12px 10px;
    }

    .features-grid,
    .guide-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-section {
        padding: 40px 0;
    }

    .hero-section h1 {
        font-size: 28px;
    }

    .input-group input,
    .output-group input {
        font-size: 16px;
        padding: 15px 20px;
    }

    .features-section,
    .usage-guide,
    .conversion-table-section,
    .faq-section {
        padding: 50px 0;
    }
}

/* SEO Content Section */
.info-section {
    margin-top: 4rem;
    padding: 3rem;
    background: #f8f9fa;
    border-radius: 15px;
}

.info-section h2 {
    font-size: 1.5rem;
    color: #333;
    margin-top: 2rem;
    margin-bottom: 1rem;
}

.info-section h2:first-of-type {
    margin-top: 0;
}

.info-section p {
    line-height: 1.8;
    color: #555;
    margin-bottom: 1.5rem;
}

.info-section ul {
    list-style: none;
    padding-left: 0;
}

.info-section ul li {
    padding: 0.8rem 0;
    padding-left: 1.5rem;
    position: relative;
    line-height: 1.6;
    color: #555;
}

.info-section ul li:before {
    content: "";
    position: absolute;
    left: 0;
    color: #007bff;
    font-weight: bold;
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.footer {
    margin-top: 4rem;
    padding: 2rem 0;
    background: #f8f9fa;
    text-align: center;
    color: #666;
}
/* 무게 변환기 추가 UI 개선 */
.converter-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 3rem;
    border-radius: 20px;
    box-shadow: 0 10px 40px rgba(102, 126, 234, 0.3);
    margin-top: 2rem;
}

.input-group {
    margin-bottom: 2rem;
}

.input-label {
    display: block;
    color: white;
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
}

.input-field {
    width: 100%;
    padding: 1rem 1.5rem;
    font-size: 1.3rem;
    border: none;
    border-radius: 12px;
    background: white;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.3s;
}

.input-field:focus {
    outline: none;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.15);
}

.select-group {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 1.5rem;
    align-items: end;
    margin-bottom: 2rem;
}

.select-wrapper {
    display: flex;
    flex-direction: column;
}

.select-label {
    color: white;
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
}

.select-field {
    padding: 1rem 1.5rem;
    font-size: 1.1rem;
    border: none;
    border-radius: 12px;
    background: white;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

.select-field:focus {
    outline: none;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.15);
}

.arrow-icon {
    color: white;
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-bottom: 0.5rem;
}

.result-card {
    background: rgba(255, 255, 255, 0.95);
    padding: 2.5rem;
    border-radius: 16px;
    text-align: center;
    box-shadow: 0 8px 30px rgba(0,0,0,0.15);
}

.result-label {
    font-size: 1rem;
    color: #666;
    font-weight: 600;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.result-value {
    font-size: 3rem;
    font-weight: 700;
    color: #667eea;
    margin-bottom: 0.5rem;
}

.result-unit {
    font-size: 1.5rem;
    color: #764ba2;
    font-weight: 600;
}

@media (max-width: 768px) {
    .select-group {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .arrow-icon {
        transform: rotate(90deg);
        padding: 1rem 0;
    }
    
    .result-value {
        font-size: 2.5rem;
    }
}