* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Arial', sans-serif;
}

body {
    background-color: #f0f8ff;
    color: #333;
}

#game-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

#header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding: 10px;
    background-color: #4a90e2;
    color: white;
    border-radius: 8px;
}

#header h1 {
    font-size: 24px;
}

#game-area {
    display: flex;
    height: 500px;
    margin-bottom: 20px;
    border-radius: 8px;
    overflow: hidden;
}

#physics-world, #fbd-display {
    flex: 1;
    height: 100%;
    background-color: white;
    border: 1px solid #ddd;
}

#physics-world {
    border-right: none;
    border-top-left-radius: 8px;
    border-bottom-left-radius: 8px;
    position: relative;
}

#fbd-display {
    border-top-right-radius: 8px;
    border-bottom-right-radius: 8px;
    position: relative;
}

#control-panel {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin-bottom: 20px;
    padding: 15px;
    background-color: #e9ecef;
    border-radius: 8px;
}

#force-tools {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 10px;
}

#angle-controls {
    display: flex;
    flex-direction: column;
    gap: 20px;
    justify-content: center;
    margin-bottom: 10px;
}

.angle-control-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 5px;
}

.angle-control-group label {
    font-size: 14px;
    font-weight: bold;
}

.angle-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
    justify-content: center;
    max-width: 600px;
}

.angle-btn {
    padding: 5px;
    min-width: 40px;
    background-color: #e0e0e0;
    color: #333;
    border: 1px solid #ccc;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 12px;
}

.angle-btn:hover {
    background-color: #d0d0d0;
}

.angle-btn.active {
    background-color: #4a90e2;
    color: white;
    border-color: #3a7bc8;
}

.force-tool {
    display: flex;
    flex-direction: column;
    align-items: center;
    cursor: pointer;
    padding: 10px;
    border-radius: 5px;
    transition: background-color 0.2s;
}

.force-tool:hover {
    background-color: #d0d0d0;
}

.force-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    margin-bottom: 5px;
    display: flex;
    justify-content: center;
    align-items: center;
    color: white;
    font-weight: bold;
}

.gravity-icon {
    background-color: #3498db;
}

.normal-icon {
    background-color: #2ecc71;
}

.friction-icon {
    background-color: #e74c3c;
}

.applied-icon {
    background-color: #9b59b6;
}

.force-label {
    font-size: 12px;
    text-align: center;
}

.force-note {
    font-size: 10px;
    text-align: center;
    color: #666;
    font-style: italic;
}

#object-tools {
    display: flex;
    gap: 10px;
    justify-content: center;
}

button {
    padding: 8px 15px;
    background-color: #4a90e2;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #3a7bc8;
}

#challenge-panel {
    padding: 15px;
    background-color: #e9ecef;
    border-radius: 8px;
}

#force-status {
    margin-top: 15px;
    padding-top: 10px;
    border-top: 1px solid #ccc;
}

#force-status h4 {
    margin-bottom: 10px;
}

#force-status-list {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.force-status-item {
    display: flex;
    align-items: center;
    gap: 10px;
}

.status-indicator {
    width: 15px;
    height: 15px;
    border-radius: 50%;
}

.status-correct {
    background-color: #2ecc71;
}

.status-incorrect {
    background-color: #e74c3c;
}

.status-missing {
    background-color: #95a5a6;
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 100;
    justify-content: center;
    align-items: center;
}

.modal-content {
    background-color: white;
    padding: 20px;
    border-radius: 8px;
    max-width: 500px;
    text-align: center;
}

.modal-content h2 {
    margin-bottom: 15px;
}

.modal-content p {
    margin-bottom: 15px;
}

.force-vector {
    position: absolute;
    pointer-events: none;
}

.force-arrow {
    position: absolute;
    height: 4px;
    transform-origin: left center;
    background-color: currentColor;
}

.force-arrow::after {
    content: '';
    position: absolute;
    right: -8px;
    top: -6px;
    border-left: 10px solid currentColor;
    border-top: 8px solid transparent;
    border-bottom: 8px solid transparent;
}

/* Special styling for gravity arrow to ensure it points downward */
.force-vector .force-arrow[style*="rotate(270deg)"] {
    background-color: #3498db !important;
}

.gravity-line {
    position: absolute;
    width: 4px;
    height: 80px;
    background-color: #3498db;
    top: 0;
    left: -2px; /* Center the line */
}

.gravity-arrowhead {
    position: absolute;
    width: 0;
    height: 0;
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    border-top: 10px solid #3498db;
    top: 80px;
    left: -8px;
}

.gravity-line.correct-angle {
    box-shadow: 0 0 5px 1px rgba(46, 204, 113, 0.7);
}

.force-arrow.incorrect-angle {
    background-image: linear-gradient(to right, currentColor 50%, transparent 50%);
    background-size: 10px 4px;
    background-repeat: repeat-x;
    opacity: 0.7;
}

.force-arrow.correct-angle {
    box-shadow: 0 0 5px 1px rgba(46, 204, 113, 0.7);
}

.force-arrow.incorrect-angle::after {
    opacity: 0.7;
}

.force-label-text {
    position: absolute;
    font-size: 14px;
    font-weight: bold;
    color: currentColor;
    transform: translate(-50%, -50%);
    background-color: rgba(255, 255, 255, 0.7);
    padding: 2px 5px;
    border-radius: 3px;
}

.object {
    position: absolute;
    background-color: #f39c12;
    border: 2px solid #e67e22;
}

.surface {
    position: absolute;
    background-color: #95a5a6;
}
.angle-indicators {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 5;
}

.angle-marker {
    position: absolute;
    width: 6px;
    height: 6px;
    background-color: rgba(0, 0, 0, 0.5);
    border-radius: 50%;
    transform: translate(-50%, -50%);
}

.angle-label {
    position: absolute;
    font-size: 10px;
    color: rgba(0, 0, 0, 0.7);
    transform: translate(-50%, -50%);
    white-space: nowrap;
}

.reference-lines {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.reference-line {
    position: absolute;
    background-color: rgba(0, 0, 0, 0.1);
}

.reference-line.horizontal {
    width: 100%;
    height: 1px;
    top: 50%;
    left: 0;
}

.reference-line.vertical {
    width: 1px;
    height: 100%;
    top: 0;
    left: 50%;
}
/* Incline angle indicator styles */
.incline-angle-indicator {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 5;
}

.incline-angle-arc {
    position: absolute;
    border: 2px solid rgba(0, 0, 0, 0.5);
    border-right: none;
    border-bottom: none;
    border-radius: 100% 0 0 0;
    clip-path: polygon(0% 0%, 100% 0%, 0% 100%);
    z-index: 4;
    transform: rotate(180deg);
}

.incline-angle-label {
    position: absolute;
    font-size: 14px;
    font-weight: bold;
    color: rgba(0, 0, 0, 0.7);
    transform: translate(-50%, -50%);
    background-color: rgba(255, 255, 255, 0.7);
    padding: 2px 5px;
    border-radius: 3px;
    z-index: 6;
}

.incline-reference-line {
    position: absolute;
    background-color: rgba(0, 0, 0, 0.3);
    height: 2px;
    transform-origin: left center;
    z-index: 5;
}

.incline-reference-line.inclined {
    background-color: rgba(255, 0, 0, 0.5);
    height: 2px;
    z-index: 5;
}