/* ========================================
   RESET AND BASE STYLES
   ======================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --base-font-size: 18px;
    --bg-color: #F8F5F0;
    --text-color: #1A1A1A;
    --text-secondary: #4A4A4A;
    --accent-color: #2C5F7F;
    --accent-hover: #1E4357;
    --border-color: #D4CFC5;
    --max-width: 780px;
}

html {
    font-size: var(--base-font-size);
}

/* Note: Using rem units so font sizes scale with the base size toggle */

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

/* ========================================
   LAYOUT
   ======================================== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    flex-wrap: wrap;
}

main {
    min-height: calc(100vh - 200px);
    padding: 40px 0;
}

/* ========================================
   HEADER AND NAVIGATION
   ======================================== */
.site-header {
    background-color: var(--bg-color);
    border-bottom: 2px solid var(--border-color);
    padding: 20px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.site-title {
    font-size: 1.33rem; /* 24px at 18px base */
    font-weight: 600;
    color: var(--accent-color);
    text-decoration: none;
    white-space: nowrap;
}

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

.main-nav {
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
}

.main-nav a {
    color: var(--text-color);
    text-decoration: none;
    font-size: 1rem; /* 18px at 18px base */
    padding: 8px 0;
    border-bottom: 2px solid transparent;
    transition: border-color 0.2s;
}

.main-nav a:hover,
.main-nav a:focus {
    border-bottom-color: var(--accent-color);
}

.font-toggle {
    background-color: var(--accent-color);
    color: #FFFFFF;
    border: none;
    padding: 10px 16px;
    font-size: 16px;
    font-weight: 600;
    border-radius: 4px;
    cursor: pointer;
    min-height: 44px;
    min-width: 44px;
}

.font-toggle:hover {
    background-color: var(--accent-hover);
}

/* ========================================
   TYPOGRAPHY
   ======================================== */
h1 {
    font-size: 2.67rem; /* 48px at 18px base */
    font-weight: 600;
    margin-bottom: 16px;
    line-height: 1.2;
}

h2 {
    font-size: 1.78rem; /* 32px at 18px base */
    font-weight: 600;
    margin: 48px 0 24px;
    line-height: 1.3;
}

h3 {
    font-size: 1.33rem; /* 24px at 18px base */
    font-weight: 600;
    margin: 32px 0 16px;
    line-height: 1.4;
}

p {
    font-size: 1.11rem; /* 20px at 18px base */
    margin-bottom: 20px;
    line-height: 1.7;
}

ul, ol {
    margin: 20px 0 20px 32px;
    font-size: 1.11rem; /* 20px at 18px base */
}

li {
    margin-bottom: 12px;
    line-height: 1.6;
}

.subtitle {
    font-size: 1.33rem; /* 24px at 18px base */
    font-weight: 400;
    color: var(--text-secondary);
    font-style: italic;
}

/* ========================================
   BUTTONS AND LINKS
   ======================================== */
.btn {
    display: inline-block;
    padding: 16px 32px;
    font-size: 1.11rem; /* 20px at 18px base */
    font-weight: 500;
    text-decoration: none;
    border-radius: 6px;
    min-height: 44px;
    text-align: center;
    transition: all 0.2s;
    cursor: pointer;
    border: none;
}

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

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

.btn-secondary {
    background-color: transparent;
    color: var(--accent-color);
    border: 2px solid var(--accent-color);
}

.btn-secondary:hover {
    background-color: var(--accent-color);
    color: #FFFFFF;
}

/* ========================================
   HERO SECTION
   ======================================== */
.hero {
    text-align: center;
    padding: 60px 0;
}

.hero h1 {
    font-size: 3.11rem; /* 56px at 18px base */
    margin-bottom: 24px;
}

.hero p {
    font-size: 1.33rem; /* 24px at 18px base */
    margin-bottom: 48px;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ========================================
   CONTENT SECTIONS
   ======================================== */
.section {
    margin: 48px 0;
}

.section-intro {
    font-size: 1.22rem; /* 22px at 18px base */
    color: var(--text-secondary);
    margin-bottom: 32px;
}

/* ========================================
   EXPEDITION CARDS
   ======================================== */
.expedition-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin: 32px 0;
}

.expedition-card {
    background: #FFFFFF;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 32px;
    transition: border-color 0.2s;
}

.expedition-card:hover {
    border-color: var(--accent-color);
}

.expedition-card h3 {
    margin-top: 0;
    color: var(--accent-color);
}

.expedition-card a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 500;
}

.expedition-card a:hover {
    text-decoration: underline;
}

/* ========================================
   LAB NOTEBOOK ENTRIES
   ======================================== */
.lab-entry {
    background: #FFFFFF;
    border-left: 4px solid var(--accent-color);
    padding: 32px;
    margin: 32px 0;
}

.lab-entry-date {
    font-size: 0.89rem; /* 16px at 18px base */
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 8px;
}

.lab-entry h2 {
    margin-top: 0;
    font-size: 1.56rem; /* 28px at 18px base */
}

.lab-entry-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin: 16px 0;
}

.tag {
    background-color: var(--border-color);
    color: var(--text-color);
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.78rem; /* 14px at 18px base */
}

/* ========================================
   TECHNICAL APPENDIX (Collapsible)
   ======================================== */
.appendix {
    background: #FFFFFF;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    margin: 32px 0;
}

.appendix-toggle {
    width: 100%;
    padding: 20px;
    background: transparent;
    border: none;
    font-size: 1.11rem; /* 20px at 18px base */
    font-weight: 600;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.appendix-toggle:hover {
    background-color: var(--bg-color);
}

.appendix-content {
    padding: 0 20px 20px;
    display: none;
}

.appendix-content.active {
    display: block;
}

/* ========================================
   PAPER BLOCKS (for history page)
   ======================================== */
.paper-block {
    background: #FFFFFF;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 32px;
    margin: 32px 0;
}

.paper-header {
    margin-bottom: 24px;
}

.paper-title {
    font-size: 1.33rem; /* 24px at 18px base */
    font-weight: 600;
    color: var(--accent-color);
    margin-bottom: 8px;
}

.paper-link {
    color: var(--accent-color);
    text-decoration: none;
    font-size: 1rem; /* 18px at 18px base */
}

.paper-link:hover {
    text-decoration: underline;
}

.paper-meta {
    font-size: 0.89rem; /* 16px at 18px base */
    color: var(--text-secondary);
    margin-top: 8px;
}

.explanation-levels {
    margin-top: 24px;
}

.explanation-block {
    border-top: 1px solid var(--border-color);
}

.explanation-toggle {
    width: 100%;
    padding: 16px 0;
    background: transparent;
    border: none;
    font-size: 1rem; /* 18px at 18px base */
    font-weight: 500;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-color);
    transition: color 0.2s;
}

.explanation-toggle:hover {
    color: var(--accent-color);
}

.explanation-toggle .icon {
    font-size: 1.22rem; /* 22px at 18px base */
    transition: transform 0.2s;
    color: var(--accent-color);
}

.explanation-toggle.active .icon {
    transform: rotate(180deg);
}

.explanation-content {
    padding: 0 0 16px 0;
    display: none;
    font-size: 1rem; /* 18px at 18px base */
    line-height: 1.7;
}

.explanation-content.active {
    display: block;
}

.explanation-content p {
    font-size: 1rem; /* 18px at 18px base */
    margin-bottom: 16px;
}

/* ========================================
   EXPLORER PANEL (Home Page)
   ======================================== */
.explorer-panel {
    background: #FFFFFF;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 32px;
    margin: 48px 0;
}

.explorer-panel h2 {
    margin-top: 0;
    color: var(--accent-color);
}

.explorer-group {
    margin: 32px 0;
}

.explorer-group:last-child {
    margin-bottom: 0;
}

.explorer-group h3 {
    font-size: 1.22rem; /* 22px at 18px base */
    margin-top: 0;
    margin-bottom: 16px;
    color: var(--text-color);
}

.explorer-group ul {
    margin: 0;
    padding: 0;
    list-style: none;
}

.explorer-group li {
    margin-bottom: 12px;
    padding-left: 20px;
    position: relative;
}

.explorer-group li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--accent-color);
}

.explorer-group li.empty-message {
    color: var(--text-secondary);
    font-style: italic;
}

.explorer-group li.empty-message::before {
    content: "✓";
}

.explorer-group a {
    color: var(--accent-color);
    text-decoration: none;
    font-size: 1.11rem; /* 20px at 18px base */
}

.explorer-group a:hover {
    text-decoration: underline;
}

/* ========================================
   CONTEXT BOX (Concept Pages)
   ======================================== */
.context-box {
    background: #FFF9E6;
    border-left: 4px solid var(--accent-color);
    padding: 20px;
    margin: 32px 0;
    font-size: 1.11rem; /* 20px at 18px base */
    line-height: 1.7;
    color: var(--text-color);
}

/* ========================================
   BADGES (Site Map & Content Lists)
   ======================================== */
.badge {
    display: inline-block;
    font-size: 0.72rem; /* 13px at 18px base */
    font-weight: 600;
    padding: 3px 8px;
    border-radius: 4px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-left: 8px;
}

.badge-unvisited {
    background-color: #E8F4F8;
    color: var(--accent-color);
}

.badge-new {
    background-color: #FFF4E6;
    color: #C87A2F;
}

/* ========================================
   SITE MAP PAGE
   ======================================== */
.map-list {
    margin: 24px 0 48px;
    padding: 0;
    list-style: none;
}

.map-list li {
    margin-bottom: 16px;
    padding-left: 24px;
    position: relative;
}

.map-list li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--accent-color);
    font-weight: bold;
}

.map-list a {
    color: var(--accent-color);
    text-decoration: none;
    font-size: 1.11rem; /* 20px at 18px base */
}

.map-list a:hover {
    text-decoration: underline;
}

/* ========================================
   FOOTER
   ======================================== */
.site-footer {
    text-align: center;
    padding: 40px 20px;
    margin-top: 80px;
    border-top: 2px solid var(--border-color);
    color: var(--text-secondary);
    font-style: italic;
}

/* ========================================
   RESPONSIVE BREAKPOINTS
   ======================================== */

/* iPad portrait and smaller */
@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        align-items: flex-start;
    }

    .main-nav {
        order: 3;
        width: 100%;
        flex-direction: column;
        gap: 12px;
    }

    .font-toggle {
        order: 2;
    }

    .hero h1 {
        font-size: 2.22rem; /* 40px at 18px base */
    }

    .hero p {
        font-size: 1.22rem; /* 22px at 18px base */
    }

    h1 {
        font-size: 2rem; /* 36px at 18px base */
    }

    h2 {
        font-size: 1.56rem; /* 28px at 18px base */
    }

    .expedition-grid {
        grid-template-columns: 1fr;
    }
}

/* Mobile */
@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.78rem; /* 32px at 18px base */
    }

    .hero p {
        font-size: 1.11rem; /* 20px at 18px base */
    }

    h1 {
        font-size: 1.56rem; /* 28px at 18px base */
    }

    h2 {
        font-size: 1.33rem; /* 24px at 18px base */
    }

    h3 {
        font-size: 1.11rem; /* 20px at 18px base */
    }

    p, ul, ol {
        font-size: 1rem; /* 18px at 18px base */
    }

    .btn {
        width: 100%;
    }

    .hero-buttons {
        flex-direction: column;
    }
}