/* ===== BASE ===== */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    max-width: 900px;
    margin: 20px auto;
    padding: 0 20px;
    background-color: #f9f9f9;
}

/* ===== HEADINGS ===== */
h1 {
    color: #2c3e50;
    border-bottom: 2px solid #3498db;
    padding-bottom: 10px;
}

/* ===== BACK LINK ===== */
.back-link {
    display: inline-block;
    margin-bottom: 20px;
    color: #3498db;
    text-decoration: none;
    font-weight: bold;
}
.back-link:hover { text-decoration: underline; }

/* ===== STUDY GROUP (accordion) ===== */
.study-group {
    margin-top: 20px;
    border: 1px solid #d1d8dd;
    border-radius: 8px;
    background-color: #fff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    overflow: hidden;
}
.study-group summary {
    padding: 15px 20px;
    font-weight: bold;
    cursor: pointer;
    outline: none;
    display: flex;
    align-items: center;
    transition: background-color 0.2s;
}
.study-group summary:hover { background-color: #f8f9fa; }
.study-group summary h2 {
    border: none;
    padding: 0;
    margin: 0;
    font-size: 1.5em;
    color: #2c3e50;
}
.study-group summary::-webkit-details-marker { display: none; }
.study-group summary::before {
    content: '▶';
    color: #3498db;
    margin-right: 15px;
    font-size: 0.8em;
    transform-origin: center;
    transition: transform 0.2s ease-in-out;
}
.study-group[open] > summary::before { transform: rotate(90deg); }

/* ===== CURRICULUM LIST ===== */
.curriculum-list {
    list-style: none;
    padding: 0;
    margin: 0;
    border-top: 1px solid #e9ecef;
}
.curriculum-list li {
    display: flex;
    align-items: center;
    padding: 15px 20px;
    color: #34495e;
    transition: background-color 0.2s;
    border-bottom: 1px solid #f0f0f0;
}
.curriculum-list li:last-child { border-bottom: none; }
.curriculum-list li:hover { background-color: #eaf5ff; }
.curriculum-list li a {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: inherit;
    flex-grow: 1;
}
.curriculum-list .title {
    flex-grow: 1;
    text-decoration: none;
    color: inherit;
}
.curriculum-list .step {
    font-weight: bold;
    color: #7f8c8d;
    width: 30px;
    text-align: center;
    margin-right: 15px;
    flex-shrink: 0;
}
.curriculum-list .status {
    width: 80px;
    text-align: right;
    font-weight: bold;
    font-size: 0.9em;
    flex-shrink: 0;
}
.curriculum-list .external-link {
    margin: 0 10px;
    line-height: 1;
    flex-shrink: 0;
}
.curriculum-list .external-link svg {
    width: 14px;
    height: 14px;
    color: #7f8c8d;
    transition: color 0.2s;
}
.curriculum-list .external-link:hover svg { color: #3498db; }

/* ===== STATUS COLORS ===== */
.curriculum-list .done .status { color: #27ae60; }
.curriculum-list .current .status { color: #e67e22; }
.curriculum-list .pending .status { color: #7f8c8d; }
.curriculum-list .current {
    background-color: #fffbe6;
    border-left: 4px solid #f1c40f;
    padding-left: 16px;
}

/* ===== BADGES ===== */
.badge {
    display: inline-block;
    font-size: 0.7em;
    font-weight: bold;
    padding: 2px 7px;
    border-radius: 10px;
    margin-left: 8px;
    vertical-align: middle;
    letter-spacing: 0.03em;
    flex-shrink: 0;
}
.badge-new {
    background-color: #e8f8f0;
    color: #27ae60;
    border: 1px solid #a9dfbf;
}
.badge-updated {
    background-color: #eaf4ff;
    color: #2980b9;
    border: 1px solid #aed6f1;
}

/* ===== MAIN HUB PAGE — large card links ===== */
.study-list {
    list-style: none;
    padding: 0;
    margin-top: 40px;
}
.study-list li a {
    display: block;
    background-color: #fff;
    padding: 25px 30px;
    margin-bottom: 20px;
    border-radius: 8px;
    text-decoration: none;
    color: #2c3e50;
    font-size: 1.5em;
    font-weight: bold;
    border: 1px solid #d1d8dd;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    transition: transform 0.2s ease-in-out, box-shadow 0.2s ease-in-out;
}
.study-list li a:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.1);
}