/* CSS Variables for easy color management */
:root {
    --primary-color: #007BFF; /* A strong blue */
    --secondary-color: #F8F9FA; /* A very light grey for backgrounds */
    --text-color: #343A40; /* Dark grey for text */
    --light-text-color: #FFFFFF; /* White */
    --border-color: #DEE2E6; /* Light grey for borders */
    --completed-color: #28a745; /* Green for completed courses */
}

/* Base and Typography */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Roboto', sans-serif;
    color: var(--text-color);
    background-color: var(--secondary-color);
    line-height: 1.6;
}

h1, h2 {
    color: var(--primary-color);
}

/* Header and Navigation */
header {
    background-color: var(--light-text-color);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    flex-wrap: wrap; /* Allow wrapping for mobile view */
}

.header-content {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.site-name {
    font-weight: 700;
    font-size: 1.5rem;
}

/* Mobile-first navigation */
nav {
    display: none; /* Hidden by default */
    flex-direction: column;
    width: 100%;
    text-align: center;
    gap: 0.5rem;
    margin-top: 1rem;
}

nav.open {
    display: flex; /* Shown when hamburger is clicked */
}

nav a {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 700;
    padding: 0.5rem 0;
    position: relative;
}

#menu-button {
    display: block; /* Shown on mobile */
    font-size: 2rem;
    background: none;
    border: none;
    cursor: pointer;
}

/* Main Content Layout */
main {
    padding: 1rem;
    max-width: 1200px;
    margin: 0 auto;
}

.page-title {
    text-align: center;
    margin-bottom: 2rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 1rem;
}

.card {
    background-color: var(--light-text-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.about-me-content {
    display: flex;
    flex-direction: column; /* Mobile-first stack */
    align-items: center;
    text-align: center;
    gap: 1.5rem;
}

.student-photo {
    max-width: 150px;
    height: auto;
    border-radius: 50%;
    border: 3px solid var(--border-color);
}

/* Courses Section */
.course-filters {
    margin-bottom: 1.5rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.course-filters button {
    padding: 0.5rem 1rem;
    border: 1px solid var(--primary-color);
    background-color: var(--light-text-color);
    color: var(--primary-color);
    cursor: pointer;
    border-radius: 5px;
    transition: background-color 0.3s, color 0.3s;
}

.course-filters button:hover,
.course-filters button.active {
    background-color: var(--primary-color);
    color: var(--light-text-color);
}

#course-cards-container {
    display: grid;
    grid-template-columns: 1fr; /* Single column for mobile */
    gap: 1rem;
}

.course-card {
    border: 1px solid var(--border-color);
    padding: 1rem;
    border-radius: 5px;
    text-align: center;
    font-weight: 700;
}

.course-card.completed {
    border-left: 5px solid var(--completed-color);
    background-color: #f0fff4;
}

.credits-total {
    margin-top: 1.5rem;
    font-weight: 700;
    text-align: right;
}

/* Footer */
footer {
    background-color: var(--text-color);
    color: var(--light-text-color);
    text-align: center;
    padding: 2rem 1rem;
    margin-top: 2rem;
}

.social-links a {
    color: var(--light-text-color);
    margin: 0 0.5rem;
    text-decoration: none;
}