:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --text-primary: #1f2937;
    --text-secondary: #4b5563;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-card: #ffffff;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --transition: 0.2s ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --primary-color: #3b82f6;
        --primary-dark: #2563eb;
        --secondary-color: #34d399;
        --text-primary: #f9fafb;
        --text-secondary: #d1d5db;
        --bg-primary: #111827;
        --bg-secondary: #1f2937;
        --bg-card: #374151;
        --border-color: #4b5563;
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
        --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.7;
    color: var(--text-primary);
    background: var(--bg-primary);
    transition: background-color var(--transition), color var(--transition);
}

main {
    max-width: 75rem;
    margin: 0 auto;
    padding: clamp(1rem, 3vw, 2rem);
}

header {
    text-align: center;
    padding: clamp(2rem, 5vw, 4rem) clamp(1rem, 3vw, 2rem) clamp(1rem, 2vw, 2rem);
    margin-bottom: clamp(2rem, 4vw, 3rem);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}
header p {
    color: #fff;
}

h1 {
    font-size: clamp(1.75rem, 4vw, 3rem);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1rem;
    letter-spacing: -0.025em;
}

header p {
    font-size: clamp(1rem, 2vw, 1.25rem);
    opacity: 0.95;
    max-width: 50rem;
    margin: 0 auto;
    line-height: 1.6;
}

nav {
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: var(--radius-md);
    margin-bottom: 2rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

nav h2 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

nav ol {
    list-style: none;
    display: grid;
    gap: 0.5rem;
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius-sm);
    display: block;
    transition: all var(--transition);
    font-size: 0.9375rem;
}

nav a:hover,
nav a:focus {
    background: var(--bg-secondary);
    color: var(--primary-color);
    transform: translateX(0.25rem);
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

section {
    margin-bottom: clamp(3rem, 6vw, 5rem);
    scroll-margin-top: 2rem;
}

h2 {
    font-size: clamp(1.5rem, 3vw, 2.25rem);
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    position: relative;
    padding-bottom: 0.75rem;
}

h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 4rem;
    height: 0.25rem;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
}

h3 {
    font-size: clamp(1.25rem, 2.5vw, 1.75rem);
    font-weight: 600;
    margin: 2rem 0 1rem;
    color: var(--text-primary);
}

p {
    margin-bottom: 1.25rem;
    font-size: clamp(1rem, 1.5vw, 1.0625rem);
    line-height: 1.8;
    color: var(--text-secondary);
}

article {
    background: var(--bg-card);
    padding: clamp(1.5rem, 3vw, 2.5rem);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
    transition: transform var(--transition), box-shadow var(--transition);
}

article:hover {
    transform: translateY(-0.25rem);
    box-shadow: var(--shadow-lg);
}

ul, ol {
    margin: 1.5rem 0;
    padding-left: 1.5rem;
}

li {
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

mark {
    background: linear-gradient(120deg, var(--accent-color) 0%, var(--accent-color) 100%);
    background-repeat: no-repeat;
    background-size: 100% 40%;
    background-position: 0 85%;
    padding: 0 0.25rem;
    color: var(--text-primary);
    font-weight: 600;
}

aside {
    background: linear-gradient(135deg, var(--secondary-color) 0%, #059669 100%);
    color: white;
    padding: 2rem;
    border-radius: var(--radius-lg);
    margin: 2rem 0;
    box-shadow: var(--shadow-lg);
}

aside h3 {
    color: white;
    margin-top: 0;
}

aside p {
    color: rgba(255, 255, 255, 0.95);
}

details {
    background: var(--bg-secondary);
    padding: 1.25rem;
    border-radius: var(--radius-md);
    margin: 1rem 0;
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: all var(--transition);
}

details:hover {
    box-shadow: var(--shadow-md);
}

details[open] {
    box-shadow: var(--shadow-md);
}

summary {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.0625rem;
    list-style: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

summary::-webkit-details-marker {
    display: none;
}

summary::before {
    content: '▶';
    display: inline-block;
    transition: transform var(--transition);
    font-size: 0.875rem;
}

details[open] summary::before {
    transform: rotate(90deg);
}

details p {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

blockquote {
    border-left: 4px solid var(--primary-color);
    padding: 1.5rem;
    margin: 2rem 0;
    background: var(--bg-secondary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    font-style: italic;
}

.intro-section {
    font-size: clamp(1.0625rem, 1.75vw, 1.125rem);
    line-height: 1.8;
    color: var(--text-secondary);
}

.highlight-box {
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.05) 0%, rgba(16, 185, 129, 0.05) 100%);
    border-left: 4px solid var(--primary-color);
    padding: 1.5rem;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    margin: 2rem 0;
}

.criteria-grid {
    display: grid;
    gap: 1.5rem;
    margin: 2rem 0;
}

.criteria-card {
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: var(--radius-md);
    border: 2px solid var(--border-color);
    transition: all var(--transition);
}

.criteria-card:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
    transform: translateX(0.25rem);
}

.criteria-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    font-weight: 700;
    font-size: 1.125rem;
    margin-bottom: 1rem;
}

.faq-section {
    margin-top: 3rem;
}

footer {
    text-align: center;
    padding: 3rem 1rem;
    margin-top: 4rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

footer p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

footer time {
    font-weight: 600;
    color: var(--primary-color);
}

a {
    color: var(--primary-color);
    text-decoration: underline;
    text-decoration-color: transparent;
    transition: all var(--transition);
}

a:hover,
a:focus {
    text-decoration-color: var(--primary-color);
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

@media (min-width: 48rem) {
    nav ol {
        grid-template-columns: repeat(2, 1fr);
    }

    .criteria-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 64rem) {
    nav ol {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media print {
    nav {
        display: none;
    }

    * {
        color: black !important;
        background: white !important;
    }
}

:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

::selection {
    background: var(--primary-color);
    color: white;
}