/* ==========================================================================
   Stuart M. Shieber - Academic Homepage
   Scholarly Warmth Design
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Custom Properties (Design Tokens)
   -------------------------------------------------------------------------- */
:root {
    /* Colors - Harvard-inspired warm palette */
    --color-background: #FDFBF7;
    --color-background-alt: #F5F1EA;
    --color-surface: #FFFFFF;
    --color-text: #2C2C2C;
    --color-text-muted: #5A5A5A;
    --color-text-light: #7A7A7A;
    --color-crimson: #A51C30;
    --color-crimson-dark: #8A1626;
    --color-crimson-light: #C23B4D;
    --color-accent: #1E3A5F;
    --color-border: #E0DCD4;
    --color-border-light: #EBE8E2;
    
    /* Typography */
    --font-heading: 'Crimson Pro', Georgia, 'Times New Roman', serif;
    --font-body: 'Source Sans 3', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', monospace;
    
    /* Font sizes - fluid scale */
    --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
    --text-sm: clamp(0.875rem, 0.8rem + 0.3vw, 1rem);
    --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
    --text-lg: clamp(1.125rem, 1rem + 0.5vw, 1.25rem);
    --text-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
    --text-2xl: clamp(1.5rem, 1.25rem + 1vw, 2rem);
    --text-3xl: clamp(1.875rem, 1.5rem + 1.5vw, 2.5rem);
    --text-4xl: clamp(2.25rem, 1.75rem + 2vw, 3rem);
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Layout */
    --nav-width: 220px;
    --content-max-width: 1200px;
    --page-max-width: none;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    
    /* Shadows */
    --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 20px rgba(0, 0, 0, 0.1);
}

/* --------------------------------------------------------------------------
   Reset & Base
   -------------------------------------------------------------------------- */
*, *::before, *::after {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
    min-height: 100vh;
    width: 100%;
    background-color: var(--color-background);
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-body);
    font-size: var(--text-base);
    line-height: 1.7;
    color: var(--color-text);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-crimson);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover, a:focus {
    color: var(--color-crimson-dark);
    text-decoration: underline;
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
    line-height: 1.3;
    margin-top: 0;
    margin-bottom: var(--space-md);
    color: var(--color-text);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-2xl); margin-top: var(--space-2xl); }
h3 { font-size: var(--text-xl); margin-top: var(--space-xl); }
h4 { font-size: var(--text-lg); }

p {
    margin-top: 0;
    margin-bottom: var(--space-md);
}

strong, b {
    font-weight: 600;
}

blockquote {
    margin: var(--space-lg) 0;
    padding: var(--space-md) var(--space-lg);
    border-left: 4px solid var(--color-crimson);
    background: var(--color-background-alt);
    font-style: italic;
}

blockquote p {
    margin-bottom: 0;
}

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background: var(--color-background-alt);
    padding: 0.15em 0.4em;
    border-radius: 3px;
}

/* --------------------------------------------------------------------------
   Page Layout
   -------------------------------------------------------------------------- */
.page-wrapper {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.page-body {
    display: flex;
    flex: 1;
    max-width: var(--page-max-width);
    margin: 0 auto;
    width: 100%;
    padding: 0 var(--space-lg);
}

/* --------------------------------------------------------------------------
   Site Header
   -------------------------------------------------------------------------- */
.site-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-xl) var(--space-lg);
}

.header-content {
    max-width: var(--page-max-width);
    margin: 0 auto;
}

.site-title {
    font-size: var(--text-3xl);
    font-weight: 600;
    margin: 0 0 var(--space-sm) 0;
}

.site-title a {
    color: var(--color-text);
    text-decoration: none;
}

.site-title a:hover {
    color: var(--color-crimson);
    text-decoration: none;
}

.site-subtitle {
    margin: 0;
}

.site-subtitle p {
    margin: 0;
    font-size: var(--text-sm);
    line-height: 1.5;
}

.site-subtitle a {
    color: var(--color-crimson);
}

.site-subtitle .university {
    font-weight: 600;
    color: var(--color-text);
    margin-top: var(--space-xs);
}

/* --------------------------------------------------------------------------
   Navigation
   -------------------------------------------------------------------------- */
.nav-toggle {
    display: none;
    position: fixed;
    bottom: var(--space-lg);
    right: var(--space-lg);
    z-index: 1000;
    width: 56px;
    height: 56px;
    border: none;
    border-radius: 50%;
    background: var(--color-crimson);
    color: white;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    transition: background var(--transition-fast), transform var(--transition-fast);
}

.nav-toggle:hover {
    background: var(--color-crimson-dark);
    transform: scale(1.05);
}

.nav-toggle-icon,
.nav-toggle-icon::before,
.nav-toggle-icon::after {
    display: block;
    width: 24px;
    height: 2px;
    background: white;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    transition: var(--transition-fast);
}

.nav-toggle-icon {
    top: 50%;
    transform: translate(-50%, -50%);
}

.nav-toggle-icon::before,
.nav-toggle-icon::after {
    content: '';
}

.nav-toggle-icon::before {
    top: -8px;
}

.nav-toggle-icon::after {
    top: 8px;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon {
    background: transparent;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon::before {
    top: 0;
    transform: translateX(-50%) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon::after {
    top: 0;
    transform: translateX(-50%) rotate(-45deg);
}

.site-nav {
    flex-shrink: 0;
    width: var(--nav-width);
    padding: var(--space-xl) var(--space-lg) var(--space-xl) 0;
    position: sticky;
    top: 0;
    align-self: flex-start;
    max-height: 100vh;
    overflow-y: auto;
}

.nav-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-list li {
    margin-bottom: var(--space-xs);
}

.nav-list a {
    display: block;
    padding: var(--space-sm) var(--space-md);
    color: var(--color-text);
    border-radius: 6px;
    font-size: var(--text-sm);
    transition: background var(--transition-fast), color var(--transition-fast);
}

.nav-list a:hover,
.nav-list a:focus {
    background: var(--color-background-alt);
    color: var(--color-crimson);
    text-decoration: none;
}

.nav-list a.active {
    background: var(--color-crimson);
    color: white;
    font-weight: 600;
}

.nav-list a.active:hover {
    background: var(--color-crimson-dark);
    color: white;
}

.nav-list a.external::after {
    content: ' \2197';
    opacity: 0.6;
}

/* --------------------------------------------------------------------------
   Main Content
   -------------------------------------------------------------------------- */
.main-content {
    flex: 1;
    min-width: 0;
    max-width: var(--content-max-width);
    padding: var(--space-xl) 0 var(--space-3xl) var(--space-xl);
    border-left: 1px solid var(--color-border-light);
}

.page-title {
    font-size: var(--text-2xl);
    color: var(--color-crimson);
    margin-top: 0;
    margin-bottom: var(--space-xl);
    padding-bottom: var(--space-md);
    border-bottom: 2px solid var(--color-border);
}

/* --------------------------------------------------------------------------
   Lists
   -------------------------------------------------------------------------- */
ul, ol {
    margin: 0 0 var(--space-lg) 0;
    padding-left: var(--space-xl);
}

li {
    margin-bottom: var(--space-sm);
}

/* Definition lists */
dl {
    margin: 0 0 var(--space-lg) 0;
}

dt {
    font-weight: 600;
    color: var(--color-text);
    margin-top: var(--space-md);
}

dt:first-child {
    margin-top: 0;
}

dd {
    margin-left: 0;
    margin-bottom: var(--space-sm);
    padding-left: var(--space-lg);
    color: var(--color-text-muted);
}

/* Horizontal definition list */
.dl-horizontal {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: var(--space-sm) var(--space-lg);
}

.dl-horizontal dt {
    margin: 0;
    text-align: right;
    color: var(--color-text-muted);
    font-weight: normal;
}

.dl-horizontal dd {
    margin: 0;
    padding: 0;
    color: var(--color-text);
}

/* --------------------------------------------------------------------------
   Academic Tree (Students page)
   -------------------------------------------------------------------------- */
ul.tree {
    list-style: none;
    padding-left: 0;
    margin: 0;
    font-size: var(--text-sm);
    line-height: 1.4;
}

ul.tree ul {
    list-style: none;
    padding-left: 0.9em;
    margin: 0 0 0 0.6em;
}

ul.tree li {
    position: relative;
    padding: 0;
    margin: 0;
}

/* Horizontal connector to each nested item */
ul.tree ul li::before {
    content: '';
    position: absolute;
    left: -0.9em;
    top: 0;
    width: 0.7em;
    height: 0.6em;
    border-left: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

/* Vertical line connecting to next sibling */
ul.tree ul li:not(:last-child)::after {
    content: '';
    position: absolute;
    left: -0.9em;
    top: 0.6em;
    height: calc(100% - 0.6em + 1px);
    border-left: 1px solid var(--color-border);
}

ul.tree li > div {
    display: inline;
}

ul.tree > li > div {
    font-weight: 600;
}

/* --------------------------------------------------------------------------
   Publications (Biblio pages)
   -------------------------------------------------------------------------- */
.publications-note {
    background: var(--color-surface);
    padding: var(--space-lg);
    border-radius: 8px;
    border: 1px solid var(--color-border);
    margin-bottom: var(--space-xl);
    font-size: var(--text-sm);
}

/* Style bibtex2html output */
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: var(--space-lg);
}

table tr {
    border-bottom: none;
}

table td {
    padding: var(--space-xs) 0;
    vertical-align: top;
}

table td.bibtexnumber {
    width: 30px;
    color: var(--color-text-light);
    font-size: var(--text-sm);
    padding-right: var(--space-md);
}

table td.bibtexitem {
    line-height: 1.6;
}

table td.bibtexitem em {
    color: var(--color-accent);
}

/* --------------------------------------------------------------------------
   Images
   -------------------------------------------------------------------------- */
.profile-image {
    float: right;
    margin: 0 0 var(--space-lg) var(--space-xl);
    max-width: 280px;
    border-radius: 8px;
    box-shadow: var(--shadow-md);
}

.image-card {
    background: var(--color-surface);
    padding: var(--space-md);
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.site-footer {
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    padding: var(--space-lg);
    margin-top: auto;
}

.footer-content {
    max-width: var(--page-max-width);
    margin: 0 auto;
    text-align: center;
    font-size: var(--text-sm);
    color: var(--color-text-muted);
}

.footer-content p {
    margin: var(--space-xs) 0;
}

.footer-contact a {
    color: var(--color-text-muted);
}

.footer-contact a:hover {
    color: var(--color-crimson);
}

/* --------------------------------------------------------------------------
   Modal (for copyright notice)
   -------------------------------------------------------------------------- */
.modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
}

.modal-overlay.active {
    display: flex;
}

.modal-content {
    background: var(--color-surface);
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
}

.modal-header {
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h3 {
    margin: 0;
    font-size: var(--text-lg);
}

.modal-close {
    background: none;
    border: none;
    font-size: var(--text-xl);
    cursor: pointer;
    color: var(--color-text-muted);
    padding: var(--space-sm);
    line-height: 1;
}

.modal-close:hover {
    color: var(--color-crimson);
}

.modal-body {
    padding: var(--space-lg);
}

.modal-footer {
    padding: var(--space-md) var(--space-lg);
    border-top: 1px solid var(--color-border);
    text-align: right;
}

/* --------------------------------------------------------------------------
   Buttons
   -------------------------------------------------------------------------- */
.btn {
    display: inline-block;
    padding: var(--space-sm) var(--space-lg);
    font-family: var(--font-body);
    font-size: var(--text-sm);
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: background var(--transition-fast), transform var(--transition-fast);
}

.btn:hover {
    text-decoration: none;
    transform: translateY(-1px);
}

.btn-primary {
    background: var(--color-crimson);
    color: white;
}

.btn-primary:hover {
    background: var(--color-crimson-dark);
    color: white;
}

.btn-secondary {
    background: var(--color-background-alt);
    color: var(--color-text);
}

.btn-secondary:hover {
    background: var(--color-border);
}

/* --------------------------------------------------------------------------
   Utilities
   -------------------------------------------------------------------------- */
.clearfix::after {
    content: '';
    display: table;
    clear: both;
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.text-muted {
    color: var(--color-text-muted);
}

.text-small {
    font-size: var(--text-sm);
}

/* --------------------------------------------------------------------------
   Responsive Design
   -------------------------------------------------------------------------- */
@media (max-width: 900px) {
    .page-body {
        flex-direction: column;
        padding: 0 var(--space-md);
    }
    
    .nav-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }
    
    .site-nav {
        position: fixed;
        bottom: calc(56px + var(--space-lg) + var(--space-md));
        right: var(--space-lg);
        width: auto;
        min-width: 200px;
        max-width: calc(100vw - var(--space-lg) * 2);
        padding: var(--space-md);
        background: var(--color-surface);
        border-radius: 12px;
        box-shadow: var(--shadow-lg);
        z-index: 999;
        opacity: 0;
        visibility: hidden;
        transform: translateY(10px);
        transition: opacity var(--transition-base), visibility var(--transition-base), transform var(--transition-base);
    }
    
    .site-nav.nav-open {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }
    
    .main-content {
        padding: var(--space-lg) 0 var(--space-2xl) 0;
        border-left: none;
    }
    
    .profile-image {
        float: none;
        margin: 0 auto var(--space-lg) auto;
        max-width: 200px;
    }
    
    .dl-horizontal {
        grid-template-columns: 1fr;
    }
    
    .dl-horizontal dt {
        text-align: left;
        margin-top: var(--space-md);
    }
    
    .dl-horizontal dt:first-child {
        margin-top: 0;
    }
}

@media (max-width: 600px) {
    .site-header {
        padding: var(--space-lg) var(--space-md);
    }
    
    .site-title {
        font-size: var(--text-2xl);
    }
    
    .site-subtitle p {
        font-size: var(--text-xs);
    }
}

/* --------------------------------------------------------------------------
   Print Styles
   -------------------------------------------------------------------------- */
@media print {
    .nav-toggle,
    .site-nav {
        display: none;
    }
    
    .main-content {
        border: none;
        padding: 0;
        max-width: none;
    }
    
    a {
        color: inherit;
        text-decoration: underline;
    }
    
    .site-footer {
        border-top: 1px solid #ccc;
    }
}