* {
    box-sizing: border-box;
}

:root {
    --primary-color: #3498db;
    --primary-hover: #2980b9;
    --bg-color: #f5f6fa;
    --toolbar-bg: #ffffff;
    --border-color: #dcdde1;
    --text-color: #2f3640;
    --success-color: #27ae60;
    --accent-color: #e67e22;
}

body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
}

header {
    background-color: var(--toolbar-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 10px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
}

header h1 {
    margin: 0;
    font-size: 1.2rem;
    font-weight: 600;
}

#exercise-nav {
    display: flex;
    align-items: center;
    gap: 15px;
}

#exercise-nav button {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    cursor: pointer;
    padding: 5px 10px;
    transition: background 0.2s;
}

#exercise-nav button:hover {
    background-color: var(--bg-color);
}

main {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 10px;
    gap: 10px;
    position: relative;
    min-height: 0;
}

#toolbar {
    background-color: var(--toolbar-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px;
    display: flex;
    gap: 8px;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
}

.tool-btn {
    width: 40px;
    height: 40px;
    background: none;
    border: 1px solid transparent;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    color: var(--text-color);
}

.tool-btn svg {
    width: 24px;
    height: 24px;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
}

.tool-btn:hover {
    background-color: var(--bg-color);
    border-color: var(--border-color);
}

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

.spacer {
    flex: 1;
}

#reset-btn,
#check-btn,
#help-btn {
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    border: none;
    transition: background 0.2s;
}

#reset-btn {
    background-color: #e74c3c;
    color: white;
}

#reset-btn:hover {
    background-color: #c0392b;
}

#check-btn {
    background-color: var(--primary-color);
    color: white;
}

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

#help-btn {
    background-color: #f1c40f;
    color: #2c3e50;
}

#help-btn:hover {
    background-color: #f39c12;
}

#canvas-container {
    flex: 1;
    position: relative;
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    cursor: crosshair;
    min-height: 0;
}

#geometry-canvas {
    width: 100%;
    height: 100%;
}

#instructions {
    position: absolute;
    top: 15px;
    right: 15px;
    background: rgba(255, 255, 255, 0.9);
    padding: 10px 15px;
    border-radius: 4px;
    border-left: 4px solid var(--primary-color);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    max-width: 300px;
    pointer-events: none;
}

#feedback {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--success-color);
    color: white;
    padding: 20px 40px;
    border-radius: 50px;
    font-size: 2rem;
    font-weight: bold;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.2);
    animation: popIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    z-index: 100;
}

#tool-instructions {
    position: absolute;
    top: 15px;
    /* Déplacé en haut */
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--accent-color);
    /* Orange pour bien le voir */
    color: white;
    /* Texte blanc pour le contraste */
    padding: 10px 20px;
    border-radius: 4px;
    font-size: 0.95rem;
    font-weight: 600;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    pointer-events: none;
    transition: opacity 0.2s ease;
    z-index: 100;
    /* Bien au-dessus de tout */
    display: block;
    max-width: 80%;
    text-align: center;
}

/* Modal Styles */
.modal {
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: #fff;
    padding: 20px;
    border-radius: 8px;
    width: 80%;
    max-width: 500px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
    position: relative;
    max-height: 80vh;
    overflow-y: auto;
}

.close-btn {
    position: absolute;
    top: 10px;
    right: 15px;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
    color: #aaa;
}

.close-btn:hover {
    color: #000;
}

#help-body ul {
    padding-left: 20px;
}

#help-body li {
    margin-bottom: 10px;
}

.hidden {
    display: none !important;
}

@keyframes popIn {
    0% {
        transform: translate(-50%, -50%) scale(0.5);
        opacity: 0;
    }

    100% {
        transform: translate(-50%, -50%) scale(1);
        opacity: 1;
    }
}

footer {
    background-color: var(--toolbar-bg);
    border-top: 1px solid var(--border-color);
    padding: 5px 20px;
    text-align: center;
    font-size: 0.8rem;
    color: #7f8c8d;
}

footer p {
    margin: 5px 0;
}