:root {
    --bg-gradient: linear-gradient(180deg, #1f2937, #111827);
    --text-color: #e5e7eb;
    --text-secondary: #9ca3af;
    --card-bg: rgba(31, 41, 55, 0.5);
    --card-border: rgba(255, 255, 255, 0.1);
    --card-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --input-bg: #374151;
    --input-text: #f9fafb;
    --label-color: #d1d5db;
    --accent-color: #6366f1;
    --accent-color-dark: #4f46e5;
    --highlight-color: #fbbf24;
}

body.light-mode {
    --bg-gradient: linear-gradient(180deg, #ffffff, #f9fafb);
    --text-color: #1f2937;
    --text-secondary: #4b5563;
    --card-bg: rgba(255, 255, 255, 0.8);
    --card-border: rgba(0, 0, 0, 0.1);
    --card-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
    --input-bg: #e5e7eb;
    --input-text: #111827;
    --label-color: #374151;
    --accent-color: #818cf8;
    --accent-color-dark: #6366f1;
    --highlight-color: #f59e0b;
}

body {
    margin: 0;
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-gradient);
    color: var(--text-color);
    transition: background 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 48px 20px 120px;
}

h1 {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 16px;
    letter-spacing: -0.05em;
}

.subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 48px;
    line-height: 1.7;
    font-size: 1.1rem;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 24px;
    padding: 32px;
    margin-bottom: 24px;
    box-shadow: var(--card-shadow);
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
}

.row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 24px;
    color: var(--text-color);
}

label {
    display: block;
    margin-bottom: 10px;
    color: var(--label-color);
    font-size: 0.9rem;
    font-weight: 500;
}

select, button {
    width: 100%;
    padding: 14px;
    border-radius: 12px;
    border: none;
    background: var(--input-bg);
    color: var(--input-text);
    font-size: 1rem;
    margin-bottom: 16px;
    transition: all 0.2s ease;
    cursor: pointer;
}

select:focus, button:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

button#analyzeBtn {
    background: var(--accent-color);
    color: white;
    font-weight: 700;
    font-size: 1.1rem;
    margin-top: 16px;
}

button#analyzeBtn:hover {
    background: var(--accent-color-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.hidden { display: none; }

.result {
    line-height: 1.8;
    font-size: 1rem;
}

.section-title {
    margin-top: 28px;
    margin-bottom: 10px;
    font-weight: 700;
    color: var(--label-color);
    font-size: 1.1rem;
    border-left: 3px solid var(--accent-color);
    padding-left: 12px;
}

.highlight {
    color: var(--highlight-color);
    font-weight: 700;
}

.site-header {
    padding: 16px 0;
    border-bottom: 1px solid var(--card-border);
    position: sticky;
    top: 0;
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    z-index: 10;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
    margin: 0 auto;
}

.site-header nav a {
    margin-right: 24px;
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.2s ease;
}
.site-header nav a:hover {
    color: var(--text-color);
}

.content-page {
    padding-top: 40px;
}
.content-page h1, .content-page h2 {
    text-align: left;
}
.content-page p {
    line-height: 1.8;
    color: var(--text-secondary);
}

#theme-toggle {
    width: auto;
    height: auto;
    padding: 8px 16px;
    border-radius: 30px;
    background: var(--input-bg);
    color: var(--input-text);
    cursor: pointer;
    border: 1px solid transparent;
    margin-bottom: 0;
    font-weight: 600;
}
#theme-toggle:hover {
    border-color: var(--card-border);
}

ul {
  line-height: 1.8;
  padding-left: 20px;
}