@import url('https://fonts.googleapis.com/css2?family=Bogle:wght@400;700&display=swap');

/* ==========================================================================
   Design System: Tokens
   ========================================================================== */
:root {
    /* Neutral Color Scale */
    --neutral-0: #FFFFFF;
    --neutral-100: #D8C3A5;
    --neutral-200: #F0EDE9;
    --neutral-300: #E6E2DD;
    --neutral-700: #888888;
    --neutral-800: #485063;
    --neutral-900: #282E3C;

    /* Accent Color Scale */
    --accent-100: #EBF4F4;
    --accent-200: #D0E3E2;
    --accent-500: #D8C3A5;
    --accent-600: #888888;
    --accent-700: #3A5957;
    --accent-900: #213332;

    /* Functional Colors */
    --color-background: var(--neutral-900);
    --color-surface: var(--neutral-800);
    --color-text-primary: var(--neutral-100);
    --color-text-secondary: var(--neutral-700);
    --color-text-interactive: var(--accent-500);
    --color-text-interactive-hover: var(--accent-600);
    --color-border: var(--neutral-700);
    --color-focus-ring: var(--accent-500);

    /* Typography */
    --font-sans: 'Bogle', sans-serif;
    --font-size-h1: 2.488rem;
    --font-size-h2: 2.074rem;
    --font-size-h3: 1.728rem;
    --font-size-body: 1rem;
    --font-size-nav: 1.2rem;
    --font-size-caption: 0.833rem;
    --line-height-tight: 1.2;
    --line-height-heading: 1.3;
    --line-height-body: 1.7;
    --line-height-loose: 1.5;

    /* Spacing */
    --space-1: 4px;
    --space-2: 8px;
    --space-3: 12px;
    --space-4: 16px;
    --space-5: 24px;
    --space-6: 32px;
    --space-7: 48px;
    --space-8: 64px;
    --space-9: 96px;

    /* Motion */
    --duration-quick: 150ms;
    --duration-moderate: 300ms;
    --ease-out: cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);

    /* Layout */
    --max-content-width: 1100px;
    --header-height: 72px;
}

/* ==========================================================================
   Global Styles
   ========================================================================== */
*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-background);
    color: var(--color-text-primary);
    margin: 0;
    padding-top: var(--header-height);
    line-height: var(--line-height-body);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

h1,
h2,
h3 {
    color: var(--color-text-primary);
    font-weight: 600;
    line-height: var(--line-height-tight);
    text-wrap: balance;
}

h1 {
    font-size: var(--font-size-h1);
    letter-spacing: -0.02em;
}

h2 {
    font-size: var(--font-size-h2);
    letter-spacing: -0.015em;
}

h3 {
    font-size: var(--font-size-h3);
    letter-spacing: -0.01em;
}

p {
    max-width: 65ch;
}

a {
    color: var(--color-text-interactive);
    text-decoration: none;
    transition: color var(--duration-quick) var(--ease-out);
}

a:hover {
    color: var(--color-text-interactive-hover);
}



/* ==========================================================================
   Layout
   ========================================================================== */
.main-container {
    max-width: var(--max-content-width);
    margin: 0 auto;
    padding: var(--space-8) var(--space-6);
}

.two-column-layout {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: var(--space-9);
    align-items: center;
}

/* ==========================================================================
   Components
   ========================================================================== */

/* Skip Link */
.skip-link {
    position: absolute;
    top: -100px;
    left: 1rem;
    background: var(--color-text-primary);
    color: var(--color-background);
    padding: var(--space-3) var(--space-4);
    z-index: 9999;
    transition: top var(--duration-moderate) var(--ease-in-out);
    border-bottom-left-radius: var(--space-2);
    border-bottom-right-radius: var(--space-2);
}

.skip-link:focus {
    top: 0;
}

/* Header */
.site-header {
    background-color: var(--color-background);
    padding: 0;
    height: var(--header-height);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    display: flex;
    justify-content: center;
    align-items: center;
}

.site-header::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 10%;
    width: 80%;
    height: 1px;
    background-color: var(--neutral-700);
}

.header-content {
    width: 80%;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--neutral-100);
}

.nav-brand:hover {
    color: var(--neutral-100);
}

.nav-links {
    margin-left: auto;
}

.nav-links a {
    font-size: var(--font-size-nav);
    color: var(--neutral-100);
    padding: var(--space-2) var(--space-4);
    border-radius: var(--space-2);
    transition: background-color var(--duration-quick) ease, color var(--duration-quick) ease;
    outline: 2px solid transparent;
    outline-offset: 4px;
    font-weight: 700;
}

.nav-links a:hover {
    background-color: var(--neutral-800);
    color: var(--color-text-primary);
}

.nav-links a:focus-visible {
    outline-color: var(--color-focus-ring);
}

.nav-links a.active {
    background-color: var(--neutral-900);
    color: var(--neutral-100);
    font-weight: 500;
}

/* Hero */
.about {
    font-size: 1.125rem;
    line-height: 1.8;
    color: var(--color-text-primary);
}

#profile {
    width: 100%;
    max-width: 320px;
    height: auto;
    aspect-ratio: 1 / 1;
    object-fit: cover;
    border-radius: var(--space-3);
    border: 1px solid var(--color-border);
}

/* Card */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--space-6);
}

.card {
    background-color: var(--neutral-800);
    border: 1px solid var(--neutral-700);
    border-radius: var(--space-3);
    transition: transform var(--duration-moderate) var(--ease-out), box-shadow var(--duration-moderate) var(--ease-out);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: 100%;
    outline: 2px solid transparent;
    outline-offset: 4px;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px hsla(228, 14%, 10%, 0.08);
}

.card:focus-within {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px hsla(228, 14%, 10%, 0.08);
    outline-color: var(--color-focus-ring);
}

.card-content {
    padding: var(--space-5);
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.card-title {
    font-size: var(--font-size-h3);
    color: var(--color-text-primary);
    margin: 0 0 var(--space-2) 0;
}

.card-excerpt {
    color: var(--color-text-secondary);
    flex-grow: 1;
    margin-bottom: var(--space-4);
}

.card-link {
    font-weight: 500;
    text-decoration: none;
}

.card-link::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
}

/* Paper List */
.paper-list {
    list-style: none;
    padding: 0;
}

.paper-item {
    margin-bottom: var(--space-2);
}

.paper-link {
    display: block;
    padding: var(--space-4);
    border-radius: var(--space-2);
    transition: background-color var(--duration-quick) ease;
    position: relative;
}

.paper-link:hover {
    background-color: var(--neutral-800);
}

.paper-title {
    display: block;
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--color-text-primary);
}

.paper-authors,
.paper-venue {
    display: block;
    font-size: var(--font-size-caption);
    color: var(--color-text-secondary);
}

.paper-authors {
    margin: var(--space-1) 0;
}

/* Footer */
.site-footer {
    background-color: var(--color-background);
    color: var(--neutral-100);
    text-align: center;
    padding: var(--space-7) var(--space-6);
    margin-top: var(--space-8);
    font-size: var(--font-size-caption);
    position: relative;
}

.site-footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 10%;
    width: 80%;
    height: 1px;
    background-color: var(--neutral-700);
}

.social-links {
    display: flex;
    justify-content: center;
    gap: var(--space-5);
    margin-bottom: var(--space-4);
}

.social-links a {
    color: var(--color-text-secondary);
}

.social-links a:hover {
    color: var(--color-text-primary);
}

.social-icon {
    width: 24px;
    height: 24px;
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */
@media (max-width: 768px) {
    :root {
        --header-height: 60px;
    }

    .main-container {
        padding: var(--space-7) var(--space-5);
    }

    .site-header {
        padding: 0 var(--space-5);
    }

    .two-column-layout {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }

    #profile {
        margin-top: var(--space-5);
        max-width: 240px;
        justify-self: center;
    }

    .about {
        font-size: 1rem;
    }
}