:root {
    --primary-color: #0056b3;
    --primary-hover: #004494;
    --bg-color: #f8fbff;
    --container-bg: #ffffff;
    --text-color: #333333;
    --text-muted: #666666;
    --box-border: #e1e8f0;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

body.dark-mode {
    --bg-color: #121212;
    --container-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --text-muted: #aaaaaa;
    --box-border: #333333;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, sans-serif; background-color: var(--bg-color); color: var(--text-color); line-height: 1.6; transition: 0.3s; }

/* Header & Nav */
.site-header { background-color: var(--container-bg); box-shadow: 0 2px 10px rgba(0,0,0,0.05); position: sticky; top: 0; z-index: 1000; }
.nav-container { max-width: 1200px; margin: 0 auto; padding: 15px 20px; display: flex; justify-content: space-between; align-items: center; }
.logo { font-size: 22px; font-weight: 800; color: var(--primary-color); }
.nav-menu { display: flex; list-style: none; gap: 20px; }
.nav-menu a { text-decoration: none; color: var(--text-color); font-weight: 500; }
.nav-menu a:hover { color: var(--primary-color); }

.theme-btn { background: none; border: 1px solid var(--text-color); color: var(--text-color); padding: 5px 12px; border-radius: 6px; cursor: pointer; font-size: 13px; }

/* Main Content Layout */
.container { max-width: 1200px; margin: 40px auto; padding: 0 20px; }
.header-box { background-color: var(--primary-color); color: white; padding: 30px; border-radius: 12px; text-align: center; margin-bottom: 30px; }

.main-calculator { display: grid; grid-template-columns: 1.5fr 1fr; gap: 30px; margin-bottom: 40px; }

/* Components */
.box { background-color: var(--container-bg); padding: 30px; border-radius: 12px; border: 1px solid var(--box-border); box-shadow: var(--shadow); }
.section-title-group { display: flex; align-items: center; gap: 10px; margin-bottom: 20px; }
.step-num { background-color: var(--primary-color); color: white; width: 24px; height: 24px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: bold; }
h2 { color: var(--primary-color); font-size: 1.25em; border-bottom: 2px solid var(--bg-color); padding-bottom: 5px; flex-grow: 1; }

.input-group { margin-bottom: 15px; }
.input-group label { display: block; font-weight: bold; margin-bottom: 5px; font-size: 0.95em; }
.input-group input[type="number"] { width: 100%; padding: 10px; border: 1px solid var(--box-border); border-radius: 8px; background-color: var(--bg-color); color: var(--text-color); font-size: 16px; }
.input-help { display: block; font-size: 0.8em; color: var(--text-muted); margin-top: 4px; }
.checkbox-group { display: flex; align-items: center; gap: 10px; cursor: pointer; }

.calc-btn { width: 100%; padding: 18px; background-color: var(--primary-color); color: white; border: none; border-radius: 10px; font-size: 1.2em; font-weight: bold; cursor: pointer; margin-top: 15px; transition: 0.2s; }
.calc-btn:hover { background-color: var(--primary-hover); transform: translateY(-2px); }

/* Results */
.result-list { display: flex; flex-direction: column; gap: 12px; }
.result-item { display: flex; justify-content: space-between; padding: 10px 0; border-bottom: 1px dashed var(--box-border); }
.result-sub-group { background-color: var(--bg-color); padding: 15px; border-radius: 8px; margin: 5px 0; }
.result-item.sub { border-bottom: none; font-size: 0.9em; padding: 5px 0; }
.result-item.highlight { font-weight: bold; color: var(--primary-color); border-bottom: 2px solid var(--primary-color); padding: 15px 0; }
.result-item.final { font-size: 1.5em; font-weight: 800; color: #d32f2f; border-bottom: none; border-top: 3px double var(--text-color); padding-top: 20px; margin-top: 15px; }

/* Info Cards & AdSense Optimization */
.info-content-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; margin-top: 40px; }
.info-card { background-color: var(--container-bg); padding: 25px; border-radius: 12px; border: 1px solid var(--box-border); }
.info-card h3 { color: var(--primary-color); margin-bottom: 15px; }
.info-card ul { margin-left: 20px; margin-top: 10px; }
.tax-tip { background-color: var(--bg-color); padding: 15px; border-radius: 8px; margin-top: 15px; font-size: 0.95em; }

/* Footer Sections */
.footer-sections { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; margin-top: 60px; }
.contact-form input, .contact-form textarea { width: 100%; padding: 12px; margin-bottom: 10px; border-radius: 8px; border: 1px solid var(--box-border); background: var(--bg-color); color: var(--text-color); }
.submit-btn { background: var(--text-color); color: var(--container-bg); padding: 12px 24px; border: none; border-radius: 8px; cursor: pointer; }

.divider { margin: 60px 0; border: 0; border-top: 1px solid var(--box-border); }
.site-footer { text-align: center; padding: 40px; color: var(--text-muted); font-size: 14px; }
.footer-links { margin-top: 15px; display: flex; justify-content: center; gap: 20px; }
.footer-links a { color: var(--text-muted); text-decoration: none; }

@media (max-width: 992px) { .main-calculator, .info-content-grid, .footer-sections { grid-template-columns: 1fr; } }