/* 
 * Remote Sensing with Google Earth Engine
 * Minimalist Modern Stylesheet
 * Light Gray Theme
 */

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

:root {
    /* Color Palette - Light Grays */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #e8e8e8;
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-muted: #999999;
    --border-color: #d0d0d0;
    --accent-color: #4a90a4;
    --code-bg: #f0f0f0;
    --shadow-light: rgba(0, 0, 0, 0.05);
    --shadow-medium: rgba(0, 0, 0, 0.1);
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.7;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    padding: 20px;
    padding-top: 20px; /* Account for sticky nav */
}

/* ===== STICKY NAVIGATION ===== */
.sticky-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px var(--shadow-medium);
    z-index: 1000;
    opacity: 0;
    transform: translateY(-100%);
    transition: opacity 0.4s ease, transform 0.4s ease;
}

.sticky-nav.visible {
    opacity: 1;
    transform: translateY(0);
}

.sticky-nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 15px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand a {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--accent-color);
    text-decoration: none;
    transition: color 0.2s ease;
}

.nav-brand a:hover {
    color: #3a7a8a;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 30px;
    margin: 0;
    padding: 0;
}

.nav-links li {
    margin: 0;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s ease;
    padding: 5px 0;
    border-bottom: 2px solid transparent;
}

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

/* ===== LAYOUT CONTAINER ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    background-color: var(--bg-primary);
    padding: 40px;
    box-shadow: 0 2px 8px var(--shadow-light);
}

/* ===== HEADER ===== */
header {
    text-align: center;
    padding: 30px 0 40px;
    border-bottom: 2px solid var(--bg-tertiary);
    margin-bottom: 40px;
}

.course-title {
    font-size: 2.5rem;
    font-weight: 300;
    letter-spacing: -0.5px;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.course-subtitle {
    font-size: 1.1rem;
    font-weight: 400;
    color: var(--text-secondary);
    margin-bottom: 5px;
}

.course-description {
    font-size: 0.95rem;
    color: var(--text-muted);
    max-width: 900px;
    margin: 20px auto 0;
    font-style: italic;
    line-height: 1.6;
    text-align: left; /* Override header centering for paragraph text */
}

/* ===== BUTTONS ===== */
.lets-go-button {
    display: inline-block;
    padding: 14px 40px;
    background-color: var(--accent-color);
    color: white;
    font-weight: 600;
    font-size: 1.1rem;
    border-radius: 50px;
    text-decoration: none;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px var(--shadow-medium);
}

.lets-go-button:hover {
    background-color: #3a7a8a;
    transform: translateY(-2px);
    box-shadow: 0 6px 16px var(--shadow-medium);
    text-decoration: none;
}

.lets-go-button:active {
    transform: translateY(0);
}

/* ===== NAVIGATION ===== */
nav {
    background-color: var(--bg-secondary);
    padding: 15px;
    margin-bottom: 30px;
    border-radius: 4px;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 25px;
}

nav a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s ease;
}

nav a:hover {
    color: var(--accent-color);
}

.breadcrumb {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 20px;
}

.breadcrumb a {
    color: var(--accent-color);
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

/* ===== TYPOGRAPHY ===== */
h1 {
    font-size: 2rem;
    font-weight: 300;
    margin-bottom: 25px;
    color: var(--text-primary);
    line-height: 1.3;
}

h2 {
    font-size: 1.6rem;
    font-weight: 400;
    margin-top: 35px;
    margin-bottom: 20px;
    color: var(--text-primary);
    border-bottom: 1px solid var(--bg-tertiary);
    padding-bottom: 10px;
}

h3 {
    font-size: 1.3rem;
    font-weight: 500;
    margin-top: 25px;
    margin-bottom: 15px;
    color: var(--text-primary);
}

h4 {
    font-size: 1.1rem;
    font-weight: 500;
    margin-top: 20px;
    margin-bottom: 12px;
    color: var(--text-secondary);
}

p {
    margin-bottom: 15px;
}

strong {
    font-weight: 600;
    color: var(--text-primary);
}

em {
    font-style: italic;
    color: var(--text-secondary);
}

/* ===== LINKS ===== */
a {
    color: var(--accent-color);
    text-decoration: none;
    transition: all 0.2s ease;
}

a:hover {
    text-decoration: underline;
}

/* ===== LISTS ===== */
ul, ol {
    margin-bottom: 20px;
    padding-left: 30px;
}

li {
    margin-bottom: 10px;
    line-height: 1.7;
}

/* ===== COURSE SCHEDULE TABLE ===== */
.schedule-table {
    width: 100%;
    border-collapse: collapse;
    margin: 30px 0;
    box-shadow: 0 1px 3px var(--shadow-light);
}

.schedule-table thead {
    background-color: var(--bg-tertiary);
}

.schedule-table th {
    padding: 15px 12px;
    text-align: center;
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.schedule-table td {
    padding: 15px 12px;
    text-align: center;
    border: 1px solid var(--border-color);
    vertical-align: top;
}

.schedule-table tbody tr:nth-child(even) {
    background-color: var(--bg-secondary);
}

.schedule-table tbody tr:hover {
    background-color: #f0f0f0;
    transition: background-color 0.2s ease;
}

.schedule-table td p {
    margin-bottom: 8px;
}

.schedule-table td p:last-child {
    margin-bottom: 0;
}

.schedule-table a {
    display: inline-block;
    padding: 4px 0;
}

/* Week column */
.schedule-table td:first-child {
    font-weight: 600;
    color: var(--text-secondary);
    font-style: italic;
}

/* ===== LAB CONTENT ===== */
.lab-content {
    max-width: 900px;
    margin: 0 auto;
}

.lab-header {
    background-color: var(--bg-secondary);
    padding: 25px;
    border-radius: 4px;
    margin-bottom: 30px;
}

.lab-objective {
    background-color: #fff9e6;
    border-left: 4px solid var(--accent-color);
    padding: 15px 20px;
    margin: 20px 0;
    font-style: italic;
}

.lab-steps ol {
    counter-reset: step-counter;
    list-style: none;
    padding-left: 0;
}

.lab-steps li {
    counter-increment: step-counter;
    margin-bottom: 25px;
    padding-left: 40px;
    position: relative;
}

.lab-steps li::before {
    content: counter(step-counter);
    position: absolute;
    left: 0;
    top: 0;
    background-color: var(--accent-color);
    color: white;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.9rem;
}

/* ===== CODE BLOCKS ===== */
pre, code {
    font-family: 'Courier New', Consolas, Monaco, monospace;
    font-size: 0.9rem;
}

pre {
    background-color: var(--code-bg);
    padding: 15px 20px;
    border-radius: 4px;
    border-left: 3px solid var(--accent-color);
    overflow-x: auto;
    margin: 15px 0;
    line-height: 1.5;
}

code {
    background-color: var(--code-bg);
    padding: 2px 6px;
    border-radius: 3px;
    color: var(--text-primary);
}

pre code {
    background-color: transparent;
    padding: 0;
}

/* ===== IMAGES ===== */
img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 20px auto;
    border-radius: 4px;
    box-shadow: 0 2px 8px var(--shadow-light);
}

figure {
    margin: 25px 0;
    text-align: center;
}

figcaption {
    font-size: 0.9rem;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 10px;
}

/* ===== VIDEO EMBEDS ===== */
.video-container {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 aspect ratio */
    height: 0;
    overflow: hidden;
    margin: 25px 0;
    border-radius: 4px;
    box-shadow: 0 2px 8px var(--shadow-medium);
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

/* ===== SUBMISSION BOX ===== */
.submission-box {
    background-color: #e8f4f8;
    border: 2px solid var(--accent-color);
    border-radius: 4px;
    padding: 20px;
    margin: 30px 0;
}

.submission-box h3 {
    margin-top: 0;
    color: var(--accent-color);
}

.submission-box p {
    margin-bottom: 10px;
}

.submission-box .email-link {
    font-weight: 600;
    font-size: 1.05rem;
}

/* ===== CARDS (for module pages) ===== */
.card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 1px 3px var(--shadow-light);
    transition: box-shadow 0.3s ease;
}

.card:hover {
    box-shadow: 0 3px 10px var(--shadow-medium);
}

.card h3 {
    margin-top: 0;
}

/* ===== MODULE GRID ===== */
.module-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin: 30px 0;
}

/* ===== FOOTER ===== */
footer {
    text-align: center;
    padding: 30px 20px;
    margin-top: 50px;
    border-top: 1px solid var(--bg-tertiary);
    color: var(--text-muted);
    font-size: 0.9rem;
}

footer p {
    margin-bottom: 8px;
}

/* ===== ALERTS & NOTES ===== */
.note {
    background-color: #f0f8ff;
    border-left: 4px solid #4a90a4;
    padding: 15px 20px;
    margin: 20px 0;
    border-radius: 4px;
}

.warning {
    background-color: #fff3cd;
    border-left: 4px solid #ffb84d;
    padding: 15px 20px;
    margin: 20px 0;
    border-radius: 4px;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 768px) {
    body {
        padding: 10px;
        padding-top: 10px;
    }
    
    .container {
        padding: 20px;
    }
    
    .sticky-nav-container {
        padding: 12px 20px;
        flex-direction: column;
        gap: 10px;
    }
    
    .nav-links {
        flex-wrap: wrap;
        gap: 15px;
        justify-content: center;
    }
    
    .nav-links a {
        font-size: 0.9rem;
    }
    
    .course-title {
        font-size: 1.8rem;
    }
    
    h1 {
        font-size: 1.6rem;
    }
    
    h2 {
        font-size: 1.4rem;
    }
    
    .schedule-table {
        font-size: 0.85rem;
    }
    
    .schedule-table th,
    .schedule-table td {
        padding: 10px 8px;
    }
    
    nav ul {
        flex-direction: column;
        gap: 12px;
    }
    
    .lab-steps li {
        padding-left: 35px;
    }
    
    .module-grid {
        grid-template-columns: 1fr;
    }
}

@media print {
    body {
        background-color: white;
        padding: 0;
    }
    
    .container {
        box-shadow: none;
        padding: 20px;
    }
    
    nav {
        display: none;
    }
    
    .schedule-table {
        page-break-inside: avoid;
    }
}