:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --border-color: #cbd5e1;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    padding: 20px;
    display: flex;
    justify-content: center;
}

.container {
    width: 100%;
    max-width: 800px;
}

header {
    text-align: center;
    margin-bottom: 20px;
}

header h1 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-bottom: 5px;
}

header p {
    color: #64748b;
    font-size: 0.95rem;
}

.card {
    background: var(--card-bg);
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    margin-bottom: 20px;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
}

.form-group input {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
}

.btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 12px 20px;
    border-radius: 6px;
    font-size: 1rem;
    cursor: pointer;
    width: 100%;
    font-weight: 600;
    transition: background 0.2s;
}

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

.btn-sm {
    background-color: #0ea5e9;
    color: white;
    border: none;
    padding: 8px 14px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
}
.btn-sm:hover {
    background-color: #0284c7;
}

.hidden {
    display: none !important;
}

/* Tab Navigasi */
.tab-nav {
    display: flex;
    gap: 5px;
    margin-bottom: 15px;
}

.tab-btn {
    flex: 1;
    padding: 10px;
    background: #e2e8f0;
    border: none;
    cursor: pointer;
    font-weight: 600;
    border-radius: 6px 6px 0 0;
    transition: 0.2s;
}

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

.tab-content {
    display: none;
    background: var(--card-bg);
    padding: 20px;
    border-radius: 0 0 12px 12px;
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
}

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

.interactive-box {
    margin-top: 15px;
    text-align: center;
}

/* Garis Bilangan Pecahan */
.number-line-visual {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #f1f5f9;
    padding: 20px 10px;
    border-radius: 8px;
    margin-bottom: 15px;
    position: relative;
    border-bottom: 4px solid var(--primary-color);
}

.nl-node {
    display: flex;
    flex-direction: column;
    align-items: center;
    font-weight: bold;
    font-size: 0.9rem;
}

.nl-node span {
    width: 12px;
    height: 12px;
    background: #94a3b8;
    border-radius: 50%;
    margin-top: 5px;
    transition: 0.2s;
}

.nl-node.active span {
    background: #ef4444;
    transform: scale(1.4);
}

.controls input[type="range"] {
    width: 100%;
    margin-top: 10px;
}

.info-text {
    margin-top: 15px;
    font-style: italic;
    color: #475569;
}

/* Canvas 3D Kue */
#canvas-container {
    width: 100%;
    height: 250px;
    background: #0f172a;
    border-radius: 8px;
    margin-bottom: 15px;
}

.controls-3d {
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

/* Kuis Styling */
.quiz-item {
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid #e2e8f0;
}

.quiz-item p {
    font-weight: 600;
    margin-bottom: 8px;
}

.options-list label {
    display: block;
    margin-bottom: 6px;
    font-weight: normal;
    cursor: pointer;
}

.warning-note {
    background: #fef3c7;
    color: #92400e;
    padding: 10px;
    border-radius: 6px;
    font-size: 0.9rem;
    margin-bottom: 15px;
}

.sync-status {
    margin-top: 10px;
    font-weight: bold;
    color: #059669;
}