/* =========================================
   Variables & Reset
   ========================================= */
:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary: #10b981;
    --danger: #ef4444;
    --bg-light: #f3f4f6;
    --text-dark: #1f2937;
    --text-muted: #6b7280;
    --white: #ffffff;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --radius: 8px;
    --font-main: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-main);
    background-color: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* =========================================
   Layout & Typographie
   ========================================= */
.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 1rem;
    flex: 1;
}

h1, h2, h3 { color: var(--text-dark); margin-bottom: 1rem; }
p { margin-bottom: 1rem; color: var(--text-muted); }

/* =========================================
   Composants (Cards, Buttons, Forms)
   ========================================= */
.card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    animation: fadeIn 0.5s ease-out;
    margin-bottom: 1.5rem;
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.3s ease;
    background-color: var(--primary);
    color: var(--white);
    width: 100%;
}

@media (min-width: 600px) {
    .btn { width: auto; }
}

.btn:hover { background-color: var(--primary-hover); transform: translateY(-2px); }
.btn-secondary { background-color: transparent; border: 2px solid var(--primary); color: var(--primary); }
.btn-secondary:hover { background-color: var(--primary); color: var(--white); }

.form-group { margin-bottom: 1.5rem; }
.form-group label { display: block; font-weight: 600; margin-bottom: 0.5rem; }
.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #d1d5db;
    border-radius: var(--radius);
    font-size: 1rem;
    font-family: var(--font-main);
    transition: border-color 0.3s;
}
.form-control:focus { outline: none; border-color: var(--primary); }

.alert { padding: 1rem; border-radius: var(--radius); margin-bottom: 1rem; display: none; }
.alert.error { background-color: #fee2e2; color: var(--danger); display: block; border-left: 4px solid var(--danger);}
.alert.success { background-color: #d1fae5; color: var(--secondary); display: block; border-left: 4px solid var(--secondary);}

/* =========================================
   Styles spécifiques aux QCM
   ========================================= */
.qcm-question { font-size: 1.125rem; font-weight: 600; margin-bottom: 1rem; }
.qcm-options { list-style: none; }
.qcm-option {
    display: flex;
    align-items: center;
    padding: 0.75rem;
    border: 1px solid #e5e7eb;
    border-radius: var(--radius);
    margin-bottom: 0.5rem;
    cursor: pointer;
    transition: background 0.2s;
}
.qcm-option:hover { background-color: var(--bg-light); }
.qcm-option input[type="radio"] { margin-right: 1rem; transform: scale(1.2); cursor: pointer; }

/* Feedback de correction */
.qcm-option.correct { background-color: #d1fae5; border-color: var(--secondary); }
.qcm-option.incorrect { background-color: #fee2e2; border-color: var(--danger); }
.explanation {
    margin-top: 1rem; padding: 1rem; background-color: #eff6ff;
    border-left: 4px solid var(--primary); border-radius: 0 var(--radius) var(--radius) 0;
    display: none; font-size: 0.9rem;
}

/* Header de navigation */
.navbar {
    background: var(--white);
    padding: 1rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.nav-brand { font-weight: 700; font-size: 1.25rem; color: var(--primary); text-decoration: none; }

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: translateY(0); }
}