/* ==========================================================================
   Academic Personal Website Stylesheet
   Author: Hyunwook (Dennis) Lee
   Website: hyunwooklee.org
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Variables (Easy to customize colors and fonts)
   -------------------------------------------------------------------------- */
:root {
    /* Colors */
    --color-primary: #1a1a2e;        /* Dark navy for headers */
    --color-secondary: #16213e;       /* Secondary dark color */
    --color-accent: #0f4c75;          /* Accent blue for links */
    --color-accent-hover: #1b6ca8;    /* Hover state for links */
    --color-text: #333333;            /* Main body text */
    --color-text-light: #666666;      /* Secondary text */
    --color-background: #ffffff;      /* Main background */
    --color-background-alt: #f8f9fa;  /* Alternate background */
    --color-border: #e0e0e0;          /* Border color */

    /* Typography */
    --font-heading: 'Georgia', 'Times New Roman', serif;
    --font-body: 'Helvetica Neue', Arial, sans-serif;

    /* Spacing */
    --container-max-width: 950px;
    --nav-height: 60px;
    --section-padding: 3rem;
}

/* --------------------------------------------------------------------------
   Reset and Base Styles
   -------------------------------------------------------------------------- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-background);
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
    color: var(--color-primary);
    line-height: 1.3;
    margin-bottom: 1rem;
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 1.75rem;
    border-bottom: 2px solid var(--color-border);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
}

h3 {
    font-size: 1.25rem;
    color: var(--color-secondary);
}

p {
    margin-bottom: 1rem;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: var(--color-accent-hover);
    text-decoration: underline;
}

ul, ol {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

li {
    margin-bottom: 0.5rem;
}

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

.main-content {
    padding-top: calc(var(--nav-height) + 2rem);
    padding-bottom: var(--section-padding);
    min-height: calc(100vh - var(--nav-height) - 100px);
}

section {
    margin-bottom: var(--section-padding);
}

/* --------------------------------------------------------------------------
   Navigation
   -------------------------------------------------------------------------- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.nav-brand {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-primary);
    text-decoration: none;
}

.nav-brand:hover {
    color: var(--color-accent);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 2rem;
}

.nav-menu a {
    font-size: 0.95rem;
    color: var(--color-text);
    text-decoration: none;
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
    transition: all 0.2s ease;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--color-accent);
    border-bottom-color: var(--color-accent);
    text-decoration: none;
}

/* Mobile Navigation Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 28px;
    height: 20px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
}

.nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background-color: var(--color-primary);
    transition: all 0.3s ease;
}

/* --------------------------------------------------------------------------
   Home Page Styles
   -------------------------------------------------------------------------- */
.hero {
    display: flex;
    align-items: flex-start;
    gap: 3rem;
    margin-bottom: 2rem;
}

.hero-image {
    flex-shrink: 0;
}

.headshot {
    width: 200px;
    height: 250px;
    object-fit: cover;
    border-radius: 4px;
    border: 1px solid var(--color-border);
}

.hero-content {
    flex: 1;
}

.hero-title {
    margin-bottom: 0.25rem;
}

.hero-subtitle {
    font-size: 1.1rem;
    color: var(--color-text-light);
    margin-bottom: 1.5rem;
    font-style: italic;
}

.quick-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    margin-top: 1.5rem;
}

.btn {
    display: inline-block;
    padding: 0.6rem 1.25rem;
    border: 1px solid var(--color-accent);
    color: var(--color-accent);
    font-size: 0.9rem;
    text-decoration: none;
    transition: all 0.2s ease;
}

.btn:hover {
    background-color: var(--color-accent);
    color: white;
    text-decoration: none;
}

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

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

/* --------------------------------------------------------------------------
   CV / About Page Styles
   -------------------------------------------------------------------------- */
.cv-section {
    margin-bottom: 2.5rem;
}

.cv-section h3 {
    margin-bottom: 1rem;
    padding-bottom: 0.25rem;
}

.education-item,
.experience-item {
    margin-bottom: 1.5rem;
    padding-left: 1rem;
    border-left: 3px solid var(--color-border);
}

.institution,
.organization {
    font-weight: 600;
    color: var(--color-primary);
}

.degree,
.role {
    font-style: italic;
    color: var(--color-text-light);
}

.date {
    font-size: 0.9rem;
    color: var(--color-text-light);
}

.skills-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.skill-category h4 {
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--color-secondary);
}

.download-cv {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--color-border);
}

/* --------------------------------------------------------------------------
   Research Page Styles
   -------------------------------------------------------------------------- */
.research-item {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background-color: var(--color-background-alt);
    border-left: 4px solid var(--color-accent);
}

.research-item.featured {
    border-left-color: var(--color-primary);
    background-color: #f0f4f8;
}

.research-item h3 {
    margin-bottom: 0.5rem;
}

.research-status {
    display: inline-block;
    font-size: 0.8rem;
    padding: 0.2rem 0.6rem;
    background-color: var(--color-accent);
    color: white;
    border-radius: 3px;
    margin-bottom: 0.75rem;
}

.research-status.working-paper {
    background-color: #e67e22;
}

.research-status.in-progress {
    background-color: #27ae60;
}

.research-status.published {
    background-color: var(--color-primary);
}

/* --------------------------------------------------------------------------
   Experience Page Styles
   -------------------------------------------------------------------------- */
.experience-section {
    margin-bottom: 2.5rem;
}

.experience-item {
    margin-bottom: 2rem;
}

.experience-item h3 {
    margin-bottom: 0.25rem;
}

.experience-item .organization {
    display: block;
    margin-bottom: 0.25rem;
}

.experience-item .date {
    display: block;
    margin-bottom: 0.75rem;
}

.experience-item ul {
    margin-top: 0.5rem;
}

/* --------------------------------------------------------------------------
   Contact Page Styles
   -------------------------------------------------------------------------- */
.contact-info {
    margin-bottom: 2rem;
}

.contact-item {
    display: flex;
    align-items: center;
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

.contact-item strong {
    min-width: 100px;
    color: var(--color-secondary);
}

.contact-form {
    max-width: 500px;
    margin-top: 2rem;
    padding: 2rem;
    background-color: var(--color-background-alt);
    border: 1px solid var(--color-border);
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--color-border);
    font-family: var(--font-body);
    font-size: 1rem;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-accent);
}

.form-group textarea {
    min-height: 150px;
    resize: vertical;
}

/* --------------------------------------------------------------------------
   Blog Page Styles
   -------------------------------------------------------------------------- */
.blog-list {
    margin-top: 1rem;
}

.blog-post {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background-color: var(--color-background-alt);
    border-left: 4px solid var(--color-accent);
    transition: border-color 0.2s ease;
}

.blog-post:hover {
    border-left-color: var(--color-accent-hover);
}

.blog-date {
    display: block;
    font-size: 0.85rem;
    color: var(--color-text-light);
    margin-bottom: 0.5rem;
}

.blog-title {
    font-size: 1.35rem;
    margin-bottom: 0.75rem;
    border-bottom: none;
    padding-bottom: 0;
    color: var(--color-primary);
}

.blog-title a {
    color: inherit;
    text-decoration: none;
}

.blog-title a:hover {
    color: var(--color-accent);
}

.blog-excerpt {
    margin-bottom: 1rem;
    line-height: 1.6;
}

.blog-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.blog-tag {
    display: inline-block;
    font-size: 0.75rem;
    padding: 0.2rem 0.6rem;
    background-color: var(--color-border);
    color: var(--color-text-light);
    border-radius: 3px;
}

.blog-read-more {
    display: inline-block;
    margin-top: 0.75rem;
    font-size: 0.9rem;
    font-weight: 500;
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.footer {
    padding: 1.5rem 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
    font-size: 0.9rem;
    color: var(--color-text-light);
}

.footer p {
    margin-bottom: 0.25rem;
}

/* --------------------------------------------------------------------------
   Responsive Design
   -------------------------------------------------------------------------- */
@media (max-width: 900px) {
    :root {
        --section-padding: 2rem;
    }

    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    /* Mobile Navigation */
    .nav-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        flex-direction: column;
        background-color: var(--color-background);
        border-bottom: 1px solid var(--color-border);
        padding: 1rem 1.5rem;
        gap: 0;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all 0.3s ease;
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-menu li {
        margin: 0;
    }

    .nav-menu a {
        display: block;
        padding: 0.75rem 0;
        border-bottom: none;
    }

    /* Mobile toggle animation */
    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    /* Hero Section Mobile */
    .hero {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .hero-image {
        margin-bottom: 1rem;
    }

    .headshot {
        width: 180px;
        height: 225px;
    }

    .quick-links {
        justify-content: center;
    }

    /* Skills Grid Mobile */
    .skills-list {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.75rem;
    }

    .container {
        padding: 0 1rem;
    }

    .headshot {
        width: 150px;
        height: 190px;
    }

    .btn {
        width: 100%;
        text-align: center;
    }

    .quick-links {
        flex-direction: column;
    }
}

/* --------------------------------------------------------------------------
   Utility Classes
   -------------------------------------------------------------------------- */
.text-center {
    text-align: center;
}

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

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }

/* --------------------------------------------------------------------------
   Print Styles (for CV printing)
   -------------------------------------------------------------------------- */
@media print {
    .navbar,
    .nav-toggle,
    .footer {
        display: none;
    }

    .main-content {
        padding-top: 0;
    }

    body {
        font-size: 12pt;
    }

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

    .research-item,
    .contact-form {
        background-color: white;
        border: 1px solid var(--color-border);
    }
}