:root {
  --primary: #F59E0B;
  --primary-hover: #D97706;
  --primary-text: #0F172A;
  --bg-color: #0F172A;
  --card-bg: #1E293B;
  --card-bg-hover: #334155;
  --text-main: #F8FAFC;
  --text-sub: #94A3B8;
  --border-color: #334155;
  --border-focus: #F59E0B;
  --shadow-sm: 0 4px 14px rgba(0,0,0,0.4);
}

* { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Pretendard", sans-serif; }
html, body { width: 100%; overflow-x: hidden; background-color: var(--bg-color); color: var(--text-main); line-height: 1.5; }
body { padding: 20px 16px; padding-bottom: calc(20px + env(safe-area-inset-bottom)); }
.container { max-width: 800px; margin: 0 auto; width: 100%; position: relative; }

header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 24px; padding-bottom: 14px; border-bottom: 1px solid var(--border-color); }
.logo { font-size: 24px; font-weight: 900; color: var(--primary); text-decoration: none; cursor: pointer; }

.nav-menu { display: flex; gap: 8px; overflow-x: auto; padding-bottom: 12px; margin-bottom: 20px; -webkit-overflow-scrolling: touch; }
.nav-btn { background: var(--card-bg); border: 1px solid var(--border-color); color: var(--text-sub); padding: 8px 14px; border-radius: 8px; font-weight: 700; text-decoration: none; font-size: 14px; white-space: nowrap; }
.nav-btn.active, .nav-btn:hover { background: var(--primary); color: var(--primary-text); border-color: var(--primary); }

.calc-card { background: var(--card-bg); border-radius: 16px; padding: 28px 24px; border: 1px solid var(--border-color); box-shadow: var(--shadow-sm); margin-bottom: 24px; }
.panel-header { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; }
.panel-title { font-size: 20px; font-weight: 800; color: var(--text-main); }
.panel-hint { font-size: 14px; color: var(--text-sub); margin-bottom: 24px; }

.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-group { margin-bottom: 4px; }
.form-group.full { grid-column: span 2; }
.form-group label { display: block; font-size: 14px; font-weight: 700; color: var(--text-sub); margin-bottom: 8px; }
.input-wrapper input, .input-wrapper select { width: 100%; padding: 12px 14px; font-size: 16px; font-weight: 600; color: #fff; border: 1.5px solid var(--border-color); border-radius: 10px; background: #0F172A; outline: none; }
.input-wrapper input:focus, .input-wrapper select:focus { border-color: var(--border-focus); }

.result-box { background: #0F172A; border: 1.5px solid var(--primary); border-radius: 16px; padding: 24px; margin-top: 24px; }
.result-main { text-align: center; padding-bottom: 16px; border-bottom: 1px dashed #334155; margin-bottom: 16px; }
.result-label { font-size: 14px; font-weight: 700; color: var(--primary); margin-bottom: 6px; }
.result-value { font-size: 32px; font-weight: 900; color: #ffffff; }

.result-details { display: flex; flex-direction: column; gap: 10px; font-size: 15px; }
.detail-row { display: flex; justify-content: space-between; color: var(--text-sub); }
.detail-row strong { color: var(--text-main); }

.tip-box { margin-top: 16px; font-size: 13px; color: #CBD5E1; background: #182232; padding: 12px 14px; border-radius: 10px; border: 1px solid var(--border-color); }
.btn-copy { width: 100%; padding: 14px; margin-top: 18px; border: none; background: var(--primary); border-radius: 10px; font-size: 15px; font-weight: 800; cursor: pointer; color: var(--primary-text); }
.footer { text-align: center; color: #64748B; font-size: 13px; margin-top: 32px; }

@media (max-width: 640px) {
  .form-grid { grid-template-columns: 1fr; }
  .form-group.full { grid-column: span 1; }
}