:root {
  --primary-color: #0070ba;
  --text-color: #333;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: 'Segoe UI', system-ui; line-height: 1.6; color: var(--text-color); padding-top: 100px; }

/* 導航欄 */
nav { position: fixed; top: 0; width: 100%; padding: 1.2rem 8%; background: #fff; display: flex; justify-content: space-between; align-items: center; box-shadow: 0 2px 10px rgba(0,0,0,0.05); z-index: 1000; }
.company-name { font-size: 1.9rem; font-weight: 700; color: var(--primary-color); }
.nav-links { display: flex; list-style: none; gap: 20px; align-items: center; }

/* 漢堡圖標 */
.hamburger-btn { background: none; border: none; cursor: pointer; padding: 5px; display: flex; align-items: center; }
.hamburger-icon { width: 24px; height: 18px; display: flex; flex-direction: column; justify-content: space-between; }
.hamburger-icon span { display: block; width: 100%; height: 3px; background: var(--primary-color); border-radius: 3px; }

/* 下拉菜單 */
.nav-menu-container { position: relative; }
.dropdown-content { display: none; position: absolute; top: 45px; left: 0; background: #fff; min-width: 180px; box-shadow: 0 8px 20px rgba(0,0,0,0.1); border-radius: 8px; border: 1px solid #eee; overflow: hidden; }
.dropdown-content.show { display: block; }
.dropdown-content a { color: #555; padding: 12px 20px; text-decoration: none; display: block; }
.dropdown-content a:hover { background: #f8f9fa; color: var(--primary-color); }

/* 語言按鈕 */
.lang-btn { background: none; border: 1px solid #ddd; padding: 4px 12px; border-radius: 4px; cursor: pointer; font-weight: 600; }

/* --- 居中標題樣式 --- */
.center-title {
  text-align: center;
  margin-bottom: 2rem;
  color: var(--primary-color);
  font-size: 2.2rem;
}

/* Venmo 交替佈局樣式 */
.section { padding: 5rem 8%; border-bottom: 1px solid #eee; }
.feature-row { display: flex; align-items: center; gap: 5rem; padding: 3rem 0; }
.feature-row.reverse { flex-direction: row-reverse; }
.feature-image, .feature-text { flex: 1; }
.feature-image img { width: 100%; max-width: 550px; border-radius: 24px; box-shadow: 0 15px 35px rgba(0,0,0,0.1); transition: transform 0.3s ease; }
.feature-image img:hover { transform: translateY(-5px); }
.feature-text h2 { font-size: 2.5rem; margin-bottom: 10px; color: #111; }
.feature-subtitle { font-size: 1.5rem; color: #666; margin-bottom: 20px; font-weight: 400; }
.secondary-btn { text-decoration: none; color: var(--primary-color); font-weight: 700; font-size: 1.1rem; }

/* 計算器樣式 */
.calculator-container { max-width: 600px; margin: 0 auto; background: #fff; padding: 2.5rem; border-radius: 20px; border: 1px solid #eee; }
.sync-section { background: #f0f7ff; padding: 15px; border-radius: 12px; margin-bottom: 20px; }
.stock-tags { display: flex; gap: 10px; margin-top: 10px; flex-wrap: wrap; }
.stock-tag { background: #fff; border: 1px solid var(--primary-color); color: var(--primary-color); padding: 6px 14px; border-radius: 15px; cursor: pointer; font-size: 0.85rem; }

.input-group { margin-bottom: 1.2rem; }
.input-group label { display: block; margin-bottom: 5px; font-weight: 500; }
.input-group input { width: 100%; padding: 12px; border: 1px solid #ddd; border-radius: 8px; }
#calculate-btn { width: 100%; padding: 15px; background: var(--primary-color); color: #fff; border: none; border-radius: 30px; font-size: 1.1rem; cursor: pointer; }
.result-group { margin-top: 20px; border-top: 1px solid #eee; padding-top: 20px; }
.result-item { display: flex; justify-content: space-between; margin-bottom: 10px; font-size: 1.2rem; }
.positive { color: #28a745; font-weight: 700; }
.negative { color: #dc3545; font-weight: 700; }

footer { padding: 4rem 8%; background: #fafafa; text-align: center; }