/* ========== GROUND CALC - Shared CSS ========== */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR:wght@300;400;500;600;700;800;900&display=swap');

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

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #dbeafe;
    --accent: #f59e0b;
    --accent-dark: #d97706;
    --accent-light: #fef3c7;
    --success: #10b981;
    --success-light: #d1fae5;
    --danger: #ef4444;
    --bg: #f0f4f8;
    --bg-card: #ffffff;
    --text: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border: #e2e8f0;
    --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.1), 0 6px 10px rgba(0,0,0,0.08);
    --radius: 12px;
    --radius-lg: 16px;
}

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* ========== HEADER ========== */
.gc-header {
    background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 100%);
    color: #fff;
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 10px rgba(0,0,0,0.15);
}

.gc-header-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 16px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.gc-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: #fff;
}

.gc-logo-icon {
    font-size: 28px;
}

.gc-logo-text {
    font-size: 20px;
    font-weight: 800;
    letter-spacing: -0.5px;
}

.gc-logo-sub {
    font-size: 11px;
    font-weight: 400;
    opacity: 0.8;
    display: block;
    letter-spacing: 0.5px;
}

.gc-back-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: #fff;
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    padding: 8px 16px;
    border-radius: 8px;
    background: rgba(255,255,255,0.15);
    transition: background 0.2s;
}

.gc-back-btn:hover {
    background: rgba(255,255,255,0.25);
}

/* ========== MAIN CONTAINER ========== */
.gc-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 24px 20px 40px;
}

/* ========== MAIN PAGE - HERO ========== */
.gc-hero {
    text-align: center;
    padding: 40px 20px 20px;
}

.gc-hero-title {
    font-size: 32px;
    font-weight: 900;
    color: var(--text);
    margin-bottom: 8px;
    letter-spacing: -1px;
}

.gc-hero-desc {
    font-size: 16px;
    color: var(--text-secondary);
    max-width: 500px;
    margin: 0 auto;
}

/* ========== CALCULATOR GRID ========== */
.gc-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
    padding: 20px 0;
}

.gc-card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 28px 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    text-decoration: none;
    color: inherit;
    transition: all 0.25s ease;
    display: flex;
    flex-direction: column;
    gap: 12px;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.gc-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    opacity: 0;
    transition: opacity 0.25s;
}

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

.gc-card:hover::before {
    opacity: 1;
}

.gc-card-icon {
    font-size: 40px;
    line-height: 1;
}

.gc-card-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--text);
    letter-spacing: -0.3px;
}

.gc-card-desc {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.5;
}

.gc-card-arrow {
    margin-top: auto;
    color: var(--primary);
    font-size: 14px;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 4px;
    opacity: 0;
    transform: translateX(-8px);
    transition: all 0.25s;
}

.gc-card:hover .gc-card-arrow {
    opacity: 1;
    transform: translateX(0);
}

/* ========== CALCULATOR PAGE ========== */
.gc-calc-wrap {
    max-width: 700px;
    margin: 0 auto;
}

.gc-calc-title {
    font-size: 24px;
    font-weight: 800;
    margin-bottom: 4px;
    letter-spacing: -0.5px;
}

.gc-calc-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 24px;
}

/* ========== FORM ELEMENTS ========== */
.gc-form-section {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    margin-bottom: 20px;
}

.gc-form-section-title {
    font-size: 16px;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--bg);
    display: flex;
    align-items: center;
    gap: 8px;
}

.gc-form-group {
    margin-bottom: 16px;
}

.gc-form-group:last-child {
    margin-bottom: 0;
}

.gc-form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.gc-label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.gc-input {
    width: 100%;
    padding: 12px 14px;
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 16px;
    font-family: inherit;
    color: var(--text);
    background: var(--bg);
    transition: border-color 0.2s, box-shadow 0.2s;
    -webkit-appearance: none;
}

.gc-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
    background: #fff;
}

.gc-input::placeholder {
    color: var(--text-light);
}

.gc-select {
    width: 100%;
    padding: 12px 14px;
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 16px;
    font-family: inherit;
    color: var(--text);
    background: var(--bg);
    cursor: pointer;
    -webkit-appearance: none;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2364748b' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    padding-right: 36px;
}

.gc-select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.gc-input-group {
    display: flex;
    align-items: stretch;
}

.gc-input-group .gc-input {
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
    border-right: none;
}

.gc-input-unit {
    display: flex;
    align-items: center;
    padding: 0 14px;
    background: var(--border);
    border: 2px solid var(--border);
    border-left: none;
    border-radius: 0 10px 10px 0;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
    white-space: nowrap;
}

/* ========== BUTTONS ========== */
.gc-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 28px;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 700;
    font-family: inherit;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
}

.gc-btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: #fff;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.gc-btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(37, 99, 235, 0.4);
}

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

.gc-btn-reset {
    background: var(--bg);
    color: var(--text-secondary);
    border: 2px solid var(--border);
    margin-top: 8px;
}

.gc-btn-reset:hover {
    background: var(--border);
    color: var(--text);
}

.gc-btn-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.gc-btn-row .gc-btn {
    margin-top: 0;
}

/* ========== RESULTS ========== */
.gc-result {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow);
    border: 2px solid var(--success);
    margin-top: 20px;
    display: none;
}

.gc-result.show {
    display: block;
    animation: slideUp 0.3s ease;
}

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

.gc-result-title {
    font-size: 14px;
    font-weight: 700;
    color: var(--success);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.gc-result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--bg);
}

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

.gc-result-label {
    font-size: 14px;
    color: var(--text-secondary);
    font-weight: 500;
}

.gc-result-value {
    font-size: 20px;
    font-weight: 800;
    color: var(--primary);
}

.gc-result-value small {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
    margin-left: 4px;
}

.gc-result-highlight {
    background: var(--primary-light);
    border-radius: 10px;
    padding: 16px;
    margin-top: 12px;
    text-align: center;
}

.gc-result-highlight .gc-result-label {
    font-size: 13px;
    margin-bottom: 4px;
}

.gc-result-highlight .gc-result-value {
    font-size: 28px;
    color: var(--primary-dark);
}

/* ========== FORMULA INFO ========== */
.gc-formula {
    background: var(--accent-light);
    border-radius: var(--radius);
    padding: 16px 20px;
    margin-top: 20px;
    border-left: 4px solid var(--accent);
}

.gc-formula-title {
    font-size: 13px;
    font-weight: 700;
    color: var(--accent-dark);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.gc-formula p {
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.7;
}

.gc-formula code {
    background: rgba(245, 158, 11, 0.15);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 12px;
    font-weight: 600;
    color: var(--accent-dark);
}

/* ========== FOOTER ========== */
.gc-footer {
    text-align: center;
    padding: 30px 20px;
    color: var(--text-light);
    font-size: 13px;
    border-top: 1px solid var(--border);
    margin-top: 40px;
}

/* ========== TAB SELECTOR ========== */
.gc-tabs {
    display: flex;
    gap: 4px;
    background: var(--bg);
    padding: 4px;
    border-radius: 10px;
    margin-bottom: 20px;
}

.gc-tab {
    flex: 1;
    padding: 10px 16px;
    border: none;
    background: transparent;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    font-family: inherit;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
}

.gc-tab.active {
    background: var(--bg-card);
    color: var(--primary);
    box-shadow: var(--shadow);
}

.gc-tab:hover:not(.active) {
    color: var(--text);
}

.gc-tab-content {
    display: none;
}

.gc-tab-content.active {
    display: block;
}

/* ========== HELPER TABLE ========== */
.gc-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13px;
    margin-top: 12px;
}

.gc-table th {
    background: var(--bg);
    padding: 10px 12px;
    text-align: left;
    font-weight: 700;
    color: var(--text-secondary);
    border-bottom: 2px solid var(--border);
}

.gc-table td {
    padding: 10px 12px;
    border-bottom: 1px solid var(--bg);
    color: var(--text);
}

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

/* ========== RESPONSIVE ========== */
@media (max-width: 768px) {
    .gc-header-inner {
        padding: 12px 16px;
    }

    .gc-logo-text {
        font-size: 17px;
    }

    .gc-hero {
        padding: 24px 16px 12px;
    }

    .gc-hero-title {
        font-size: 24px;
    }

    .gc-hero-desc {
        font-size: 14px;
    }

    .gc-grid {
        grid-template-columns: 1fr 1fr;
        gap: 12px;
    }

    .gc-card {
        padding: 20px 16px;
    }

    .gc-card-icon {
        font-size: 32px;
    }

    .gc-card-title {
        font-size: 15px;
    }

    .gc-card-desc {
        font-size: 12px;
        display: none;
    }

    .gc-card-arrow {
        display: none;
    }

    .gc-container {
        padding: 16px 12px 30px;
    }

    .gc-form-section {
        padding: 18px 16px;
    }

    .gc-form-row {
        grid-template-columns: 1fr;
    }

    .gc-calc-title {
        font-size: 20px;
    }

    .gc-result-value {
        font-size: 18px;
    }

    .gc-result-highlight .gc-result-value {
        font-size: 24px;
    }

    .gc-btn-row {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .gc-grid {
        grid-template-columns: 1fr 1fr;
        gap: 10px;
    }

    .gc-card {
        padding: 16px 12px;
        gap: 8px;
    }

    .gc-card-icon {
        font-size: 28px;
    }

    .gc-card-title {
        font-size: 13px;
    }
}