:root {
    /* Base Font Sizing */
    --font-base: 16px;
    --font-hero: 44px;
    --font-title: 22px;
    
    /* Shape & Space */
    --radius-full: 9999px;
    --radius-xl: 32px;
    --radius-l: 24px;
    --radius-m: 16px;
    --radius-s: 12px;
    
    --header-height: 72px;
}

/* 
 * 테마 변수 통제권 복구 : @media 대신 명시적 클래스(.light-theme, .dark-theme) 사용 
 */
body.light-theme {
    /* 4050 웰스 매니지먼트 느낌의 차분한 딥-네이비 테마 및 라이트 테마 */
    --md-sys-color-primary: #1d4ed8;       /* 토스 스타일 딥 블루 */
    --md-sys-color-primary-container: #eff6ff;
    --md-sys-color-on-primary-container: #1e3a8a;
    
    --md-sys-color-surface: #FFFFFF;
    --md-sys-color-surface-container: #f1f5f9;  /* 아주 부드러운 그레이 */
    --md-sys-color-surface-container-high: #cbd5e1;
    
    --md-sys-color-on-surface: #0f172a;    /* 딥 그레이 블랙, 눈이 편안함 */
    --md-sys-color-on-surface-variant: #475569;
    
    --md-sys-color-outline: #e2e8f0;
    
    --md-sys-color-error: #ef4444;       /* 명확한 레드 */
    --md-sys-color-success: #10b981;     /* 제이드(에메랄드) 그린 */
    --md-sys-color-success-container: #d1fae5;
    
    --md-elevation-1: 0 4px 20px rgba(15, 23, 42, 0.05); /* 프림미엄 소프트 쉐도우 */
    --md-elevation-2: 0 10px 30px rgba(15, 23, 42, 0.08);
}

body.dark-theme {
    /* 고급스러운 딥 네이비(다크) 테마 */
    --md-sys-color-primary: #3b82f6;
    --md-sys-color-primary-container: #1e3a8a;
    --md-sys-color-on-primary-container: #dbeafe;
    
    --md-sys-color-surface: #1e293b;       /* 슬레이트 다크 */
    --md-sys-color-surface-container: #0f172a; /* 솔리드 딥 다크 네이비 */
    --md-sys-color-surface-container-high: #334155;
    
    --md-sys-color-on-surface: #f8fafc;
    --md-sys-color-on-surface-variant: #94a3b8;
    
    --md-sys-color-outline: #475569;
    
    --md-sys-color-error: #fca5a5;
    --md-sys-color-success: #34d399;
    --md-sys-color-success-container: #064e3b;
    
    --md-elevation-1: 0 4px 24px rgba(0, 0, 0, 0.4);
    --md-elevation-2: 0 10px 32px rgba(0, 0, 0, 0.5);
}

body {
    margin: 0;
    font-family: 'Noto Sans KR', 'Inter', 'Google Sans', sans-serif;
    font-size: var(--font-base);
    background-color: var(--md-sys-color-surface-container);
    color: var(--md-sys-color-on-surface);
    transition: background-color 0.4s ease, color 0.4s ease;
    -webkit-font-smoothing: antialiased;
    scroll-behavior: smooth;
}

* { box-sizing: border-box; }

p, span, label { word-break: keep-all; line-height: 1.6; }
.font-bold { font-weight: 700 !important; }
.font-hero { font-size: var(--font-hero) !important; font-weight: 900 !important; letter-spacing: -1px; }

/* Sticky Header */
.app-header {
    background: var(--md-sys-color-surface);
    padding: 0 32px; height: var(--header-height);
    display: flex; justify-content: space-between; align-items: center;
    border-bottom: 1px solid var(--md-sys-color-outline);
    position: sticky; top: 0; z-index: 1000;
    box-shadow: 0 1px 3px rgba(0,0,0,0.02);
}
.logo-wrapper { display: flex; align-items: center; gap: 8px;}
.logo-icon { font-size: 32px; }
.logo-text { color: var(--md-sys-color-on-surface); font-size: 20px; font-weight: 700; margin: 0;}
.version-badge { background: var(--md-sys-color-primary-container); color: var(--md-sys-color-primary); padding: 4px 8px; border-radius: var(--radius-s); font-size: 13px; font-weight: 700; margin-left: 8px;}

/* Switch Toggle (MD3) */
.switch-label { display: flex; align-items: center; gap: 8px; font-size: 14px; font-weight: 500; cursor: pointer; color: var(--md-sys-color-on-surface-variant); }
.switch { position: relative; display: inline-block; width: 44px; height: 24px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: var(--md-sys-color-outline); transition: .4s; }
.slider:before { position: absolute; content: ""; height: 18px; width: 18px; left: 3px; bottom: 3px; background-color: var(--md-sys-color-surface); transition: .4s; border-radius: 50%; box-shadow: 0 1px 2px rgba(0,0,0,0.2);}
input:checked + .slider { background-color: var(--md-sys-color-primary); }
input:checked + .slider:before { transform: translateX(20px); }
.slider.round { border-radius: 24px; }

/* Layout Grid & SPA Pages */
.dashboard { max-width: 1300px; margin: 0 auto; padding: 24px; position: relative; min-height: 85vh; }

.page-view {
    display: none;
    animation: fadeIn 0.4s ease forwards;
}
.page-view.active {
    display: block;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Big Page Titles */
.page-title-box { padding: 40px 16px; text-align: center; }
.page-main-title { font-size: 32px; font-weight: 800; line-height: 1.35; margin: 0 0 16px 0; letter-spacing: -0.5px; }
.page-sub-title { font-size: 17px; color: var(--md-sys-color-on-surface-variant); margin: 0; font-weight: 500;}

/* Stack Layout for Flow Inputs */
.stack-layout { display: flex; flex-direction: column; gap: 24px; max-width: 800px; margin: 0 auto; }

/* Cards (Neo-premium) */
.md-card {
    background: var(--md-sys-color-surface);
    border-radius: var(--radius-l);
    padding: 32px;
    box-shadow: var(--md-elevation-1);
    transition: transform 0.2s, box-shadow 0.2s;
}
.md-card:hover { box-shadow: var(--md-elevation-2); transform: translateY(-2px); }
.md-card h2 { margin: 0 0 28px 0; font-size: 22px; font-weight: 700; display: flex; align-items: center; gap: 10px; color: var(--md-sys-color-on-surface); letter-spacing: -0.5px;}

/* Inputs */
.form-group { margin-bottom: 32px; display: flex; flex-direction: column; }
.form-header { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 12px; }
.form-header label { font-size: 16px; font-weight: 600; color: var(--md-sys-color-on-surface); }
.form-input-box { display: flex; align-items: center; gap: 10px; }
.form-input-box input[type="number"] {
    width: 130px;
    padding: 10px 16px; border: 2px solid var(--md-sys-color-outline); border-radius: var(--radius-m);
    font-size: 18px; font-weight: 700; outline: none; background: var(--md-sys-color-surface);
    color: var(--md-sys-color-on-surface); text-align: right; transition: border-color 0.2s;
    font-family: inherit;
}
.form-input-box input[type="number"]:focus { border-color: var(--md-sys-color-primary); }
.form-input-box span { font-size: 15px; color: var(--md-sys-color-on-surface-variant); font-weight: 600; }
.highlight-input input[type="number"] { border-color: var(--md-sys-color-primary); color: var(--md-sys-color-primary); box-shadow: 0 0 0 3px var(--md-sys-color-primary-container); }

/* Range Sliders */
input[type="range"] {
    -webkit-appearance: none; appearance: none; width: 100%; background: transparent; margin-top: 12px;
}
input[type="range"]:focus { outline: none; }
input[type="range"]::-webkit-slider-runnable-track {
    width: 100%; height: 8px; cursor: pointer;
    background: var(--md-sys-color-surface-container-high);
    border-radius: var(--radius-full); border: none;
}
input[type="range"]::-webkit-slider-thumb {
    height: 24px; width: 24px; border-radius: 50%;
    background: var(--md-sys-color-primary);
    cursor: pointer; -webkit-appearance: none;
    margin-top: -8px; box-shadow: 0 2px 6px rgba(0,0,0,0.3); border: 2px solid var(--md-sys-color-surface);
}

.guide-text { font-size: 14px; color: var(--md-sys-color-on-surface-variant); margin: 8px 0 16px 0; line-height: 1.5; font-weight: 500; }
.divider { border: 0; height: 1px; background: var(--md-sys-color-outline); margin: 32px 0; }
.flex-between { display: flex; flex-direction: row; justify-content: space-between; align-items: center; margin-bottom: 0; }

/* Custom Radio */
.account-radios { background: var(--md-sys-color-surface-container); border-radius: var(--radius-m); padding: 16px; }
.custom-radio { display: flex; align-items: center; gap: 12px; font-size: 15px; font-weight: 600; cursor: pointer; color: var(--md-sys-color-on-surface-variant); padding: 12px 8px; transition: background 0.2s; border-radius: var(--radius-s); }
.custom-radio:hover { background: var(--md-sys-color-surface); }
.custom-radio input[type="radio"] { accent-color: var(--md-sys-color-primary); width: 20px; height: 20px; cursor: pointer; }

/* Mega Action Bar (SPA Transition Button) */
.bottom-action-bar {
    position: fixed; bottom: 0; left: 0; right: 0;
    padding: 24px; background: linear-gradient(to top, var(--md-sys-color-surface) 60%, transparent);
    display: flex; justify-content: center; z-index: 900;
}
.btn-mega-primary {
    background: var(--md-sys-color-primary); color: #fff;
    border: none; border-radius: var(--radius-full);
    padding: 20px 48px; font-size: 20px; font-weight: 800; cursor: pointer;
    box-shadow: 0 8px 24px rgba(29, 78, 216, 0.4);
    display: flex; align-items: center; gap: 12px; transition: transform 0.2s, box-shadow 0.2s;
    font-family: inherit; width: 100%; max-width: 800px; justify-content: center; letter-spacing: -0.5px;
}
.btn-mega-primary:hover { box-shadow: 0 12px 32px rgba(29, 78, 216, 0.5); transform: translateY(-4px); }

/* Results Nav Bar */
.page-top-nav { margin-bottom: 24px; }
.btn-back {
    background: transparent; border: none; color: var(--md-sys-color-primary); font-size: 16px; font-weight: 700;
    display: inline-flex; align-items: center; gap: 8px; cursor: pointer; padding: 12px 0; font-family: inherit;
}
.btn-back:hover { opacity: 0.8; }

.btn-share-alt {
    background: var(--md-sys-color-primary-container); color: var(--md-sys-color-primary);
    border: none; border-radius: var(--radius-m); padding: 10px 20px; font-size: 15px; font-weight: 700;
    display: flex; align-items: center; gap: 8px; cursor: pointer; transition: 0.2s; font-family: inherit;
}
.btn-share-alt:hover { background: var(--md-sys-color-primary); color: #fff; }

/* Premium Share Card (Capture Target) */
.share-card-container {
    position: absolute; left: -9999px; top: -9999px;
    width: 600px; height: 600px; padding: 40px;
    background: linear-gradient(135deg, #1e3a8a 0%, #1d4ed8 100%);
    color: #fff; font-family: 'Noto Sans KR', sans-serif;
}
.share-card-inner {
    height: 100%; border: 2px solid rgba(255,255,255,0.2); border-radius: 40px;
    padding: 60px 40px; display: flex; flex-direction: column; justify-content: space-between;
    background: rgba(255,255,255,0.05); backdrop-filter: blur(20px);
}
.share-card-header { display: flex; align-items: center; gap: 16px; }
.share-logo-icon { font-size: 48px; color: #60a5fa; }
.share-logo-text { font-size: 28px; font-weight: 900; }
.share-version { font-size: 14px; opacity: 0.7; font-weight: 500; }

.share-card-main { text-align: center; }
.share-metric { margin-bottom: 40px; }
.share-label { display: block; font-size: 18px; font-weight: 600; color: #93c5fd; margin-bottom: 12px; }
.share-age { font-size: 72px; font-weight: 900; line-height: 1; }
.share-gap { font-size: 34px; font-weight: 800; padding: 16px 32px; border-radius: 99px; display: inline-block; }
.gap-success { background: #10b981; color: #fff; }
.gap-error { background: #ef4444; color: #fff; }

.share-card-footer { border-top: 1px solid rgba(255,255,255,0.2); padding-top: 30px; text-align: center;}
.share-tagline { font-size: 16px; font-weight: 700; margin-bottom: 8px; color: #bfdbfe; }
.share-url { font-size: 20px; font-weight: 900; color: #fff; }

/* Responsive adjustments */
@media (max-width: 600px) {
    .btn-share-alt { font-size: 13px; padding: 8px 12px; }
    .btn-share-alt span { font-size: 20px; }
}

/* Dashboard Metrics */
.metrics-panel { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin-bottom: 32px; }
.metric-card {
    background: var(--md-sys-color-surface);
    border-radius: var(--radius-l);
    padding: 32px 24px;
    box-shadow: var(--md-elevation-1);
    display: flex; flex-direction: column; align-items: center; text-align: center;
}
.metric-card.primary-gradient { 
    background: linear-gradient(135deg, var(--md-sys-color-primary) 0%, #3b82f6 100%);
    color: #fff; border: none; 
}
.metric-card.primary-gradient .metric-title { opacity: 0.9; color: #fff; }
.metric-card.primary-gradient .metric-sub { opacity: 0.9; color: #fff; }
.metric-title { font-size: 15px; font-weight: 600; margin-bottom: 12px; color: var(--md-sys-color-on-surface-variant);}
.metric-value { font-size: 38px; font-weight: 800; line-height: 1.2; letter-spacing: -1px; margin-bottom: 8px; color: var(--md-sys-color-on-surface);}
.metric-sub { font-size: 14px; font-weight: 600; color: var(--md-sys-color-on-surface-variant);}

/* Big Mac Card */
.mac-card { text-align: center; }
.mac-content { display: flex; justify-content: space-around; align-items: center; margin-top: 24px;}
.mac-box { display: flex; flex-direction: column; align-items: center; gap: 12px;}
.mac-title { font-size: 16px; color: var(--md-sys-color-on-surface-variant); font-weight: 600;}
.mac-value { font-size: 34px; font-weight: 800; color: var(--md-sys-color-primary); background: var(--md-sys-color-primary-container); padding: 12px 32px; border-radius: var(--radius-full); }
.mac-arrow { font-size: 40px; color: var(--md-sys-color-outline); }
.centered-title { justify-content: center; }

/* Colors */
.text-primary { color: var(--md-sys-color-primary); }
.text-error { color: var(--md-sys-color-error); }
.text-success { color: var(--md-sys-color-success); }

/* Banner */
.accel-banner {
    background: var(--md-sys-color-success-container);
    color: var(--md-sys-color-success);
    padding: 24px; font-size: 18px; font-weight: 800;
    border-radius: var(--radius-l); margin-bottom: 32px;
    display: flex; align-items: center; justify-content: center; gap: 16px;
    box-shadow: var(--md-elevation-1); letter-spacing: -0.5px;
}
.banner-icon { font-size: 32px; }
.hidden { display: none !important; }

/* Chart Containers */
.chart-container { min-height: 480px; }
.sub-chart { min-height: 380px; }

/* SEO Content */
.seo-content {
    margin: 64px auto 40px auto; padding: 48px; max-width: 900px;
    background: var(--md-sys-color-surface); border-radius: var(--radius-xl);
    box-shadow: var(--md-elevation-1);
}
.seo-content h2 { margin-top: 0; margin-bottom: 32px; font-size: 26px; border-bottom: 2px solid var(--md-sys-color-outline); padding-bottom: 16px; color: var(--md-sys-color-primary); font-weight: 800;}
.seo-content h3 { color: var(--md-sys-color-on-surface); margin-top: 40px; font-size: 20px; font-weight: 700; margin-bottom: 16px; }
.seo-content p { line-height: 1.8; color: var(--md-sys-color-on-surface-variant); font-size: 16px; margin-bottom: 24px; word-break: keep-all; }

/* Footer */
.app-footer {
    background: var(--md-sys-color-surface); border-top: 1px solid var(--md-sys-color-outline);
    padding: 40px 32px; margin-top: 60px; text-align: center;
}
.footer-nav { margin-bottom: 24px; }
.footer-nav a { color: var(--md-sys-color-on-surface); text-decoration: none; margin: 0 20px; font-size: 15px; font-weight: 600; transition: color 0.2s; }
.footer-nav a:hover { color: var(--md-sys-color-primary); }
.footer-copy { color: var(--md-sys-color-on-surface-variant); font-size: 14px; line-height: 1.6; }

@media (max-width: 900px) {
    .metrics-panel { grid-template-columns: 1fr; }
    .mac-content { flex-direction: column; gap: 32px; }
    .mac-arrow { transform: rotate(90deg); }
    .btn-mega-primary { font-size: 18px; padding: 16px 24px; }
    .page-main-title { font-size: 26px; }
    .page-title-box { padding: 24px 16px; }
}