/* ================================================
   Enhan Liu — Academic Personal Website
   style.css
   ================================================ */

/* ---------- Reset & Root Variables ---------- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --maroon:      #8B1A2E;
    --maroon-soft: #b03048;
    --dark:        #1a1a1a;
    --gray:        #5a5a5a;
    --light-gray:  #f7f7f7;
    --border:      #ddd;
    --max-width:   820px;
    --font-main:   system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

/* ---------- Base ---------- */
html { scroll-behavior: smooth; }

body {
    font-family: var(--font-main);
    font-size: 16px;
    line-height: 1.7;
    color: var(--dark);
    background: #fff;
}

a {
    color: var(--maroon);
    text-decoration: none;
}
a:hover { text-decoration: underline; }

code {
    font-family: 'Courier New', monospace;
    font-size: 0.88em;
    background: var(--light-gray);
    padding: 0.1em 0.35em;
    border-radius: 3px;
}

/* ---------- Layout Wrapper ---------- */
.wrapper {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* ---------- Header ---------- */
header {
    padding: 2.8rem 1.5rem 1.4rem;
    max-width: var(--max-width);
    margin: 0 auto;
    border-bottom: 2px solid var(--maroon);
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    color: var(--dark);
}

header .subtitle {
    margin-top: 0.25rem;
    color: var(--gray);
    font-size: 1rem;
    font-style: italic;
}

/* ---------- Navigation ---------- */
nav {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    border-bottom: 1px solid var(--border);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 2.2rem;
    padding: 0.75rem 0;
}

nav a {
    color: var(--gray);
    font-size: 0.97rem;
    letter-spacing: 0.04em;
    transition: color 0.18s;
    text-decoration: none;
}

nav a:hover,
nav a.active {
    color: var(--maroon);
    text-decoration: none;
}

/* ---------- Main Content ---------- */
main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2.2rem 1.5rem 4rem;
}

section {
    margin-bottom: 2.8rem;
}

/* ---------- Section Headings ---------- */
h2 {
    font-size: 0.85rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--maroon);
    border-bottom: 1px solid var(--border);
    padding-bottom: 0.3rem;
    margin-bottom: 1.1rem;
}

/* ---------- About Page ---------- */
#about p + p {
    margin-top: 0.8rem;
}

.contact-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1.2rem;
    margin-top: 0.4rem;
    font-size: 0.97rem;
}

.contact-row a,
.contact-row span {
    color: var(--gray);
}

.contact-row a:hover { color: var(--maroon); text-decoration: underline; }

/* ---------- Research Projects ---------- */
.project {
    margin-bottom: 1.6rem;
}

.project-title {
    font-style: italic;
    font-weight: 600;
    line-height: 1.5;
}

.project-meta {
    color: var(--gray);
    font-size: 0.9rem;
    margin-top: 0.1rem;
}

.project-desc {
    margin-top: 0.4rem;
    font-size: 0.97rem;
}

/* ---------- CV Page ---------- */
.cv-download {
    text-align: right;
    margin-bottom: 2rem;
}

.btn {
    display: inline-block;
    padding: 0.38rem 1.1rem;
    border: 1.5px solid var(--maroon);
    color: var(--maroon);
    font-family: var(--font-main);
    font-size: 0.92rem;
    border-radius: 3px;
    cursor: pointer;
    transition: background 0.18s, color 0.18s;
    text-decoration: none;
}

.btn:hover {
    background: var(--maroon);
    color: #fff;
    text-decoration: none;
}

/* CV Entry */
.cv-entry {
    margin-bottom: 1.4rem;
}

.cv-row {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 0.3rem;
}

.cv-row strong { font-weight: 600; }

.cv-date {
    color: var(--gray);
    font-size: 0.9rem;
    white-space: nowrap;
    flex-shrink: 0;
}

.cv-sub {
    font-style: italic;
    color: var(--gray);
    font-size: 0.95rem;
}

.cv-list {
    margin: 0.35rem 0 0 1.4rem;
    font-size: 0.95rem;
}

.cv-list li {
    margin-bottom: 0.2rem;
}

.cv-skills-grid {
    display: grid;
    grid-template-columns: 9rem 1fr;
    gap: 0.4rem 1rem;
    font-size: 0.97rem;
}

.cv-skills-grid dt {
    font-weight: 600;
    color: var(--gray);
}

/* ---------- Notes Page ---------- */
.notes-intro {
    color: var(--gray);
    font-style: italic;
    margin-bottom: 1.5rem;
    font-size: 0.97rem;
}

.note-entry {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 0.3rem;
    padding: 0.7rem 0;
    border-bottom: 1px solid var(--border);
}

.note-entry:last-child { border-bottom: none; }

.note-title { font-weight: 600; }
.note-title a { color: var(--dark); }
.note-title a:hover { color: var(--maroon); }

.note-tag {
    display: inline-block;
    font-size: 0.8rem;
    background: var(--light-gray);
    color: var(--gray);
    padding: 0.1em 0.5em;
    border-radius: 10px;
    margin-left: 0.5rem;
}

.note-date {
    color: var(--gray);
    font-size: 0.88rem;
    white-space: nowrap;
}

/* ---------- Footer ---------- */
footer {
    text-align: center;
    padding: 1.4rem 1.5rem;
    color: #999;
    font-size: 0.85rem;
    border-top: 1px solid var(--border);
}

footer a { color: #999; }
footer a:hover { color: var(--maroon); }

/* ---------- Responsive ---------- */
@media (max-width: 600px) {
    body { font-size: 16px; }
    header h1 { font-size: 1.9rem; }
    nav ul { gap: 1.4rem; }
    .cv-row { flex-direction: column; gap: 0; }
    .cv-skills-grid { grid-template-columns: 1fr; }
    .note-entry { flex-direction: column; gap: 0.2rem; }
}