:root {
    --primary-color: #4361ee;
    --primary-hover: #3a56d4;
    --secondary-color: #6c757d;
    --secondary-hover: #5a6268;
    --success-color: #2ecc71;
    --success-hover: #27ae60;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-muted: #6c757d;
    --border-color: #e9ecef;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    --border-radius: 12px;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* HEADER */
.app-header {
    background-color: var(--card-bg);
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo-container {
    max-width: 1000px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    padding: 0 20px;
    gap: 20px;
}

.logo {
    height: 50px;
    width: auto;
    object-fit: contain;
}

.app-header h1 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
}

/* MAIN CONTAINER */
.app-container {
    max-width: 800px;
    margin: 40px auto;
    padding: 0 20px;
}

/* VIEWS */
.view {
    display: none;
    animation: fadeIn 0.4s ease-in-out;
}

.view.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* CARDS */
.card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 40px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

.card h2 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: var(--text-color);
}

.subtitle, .question-text {
    color: var(--text-muted);
    margin-bottom: 25px;
}

/* FORMS */
.input-group {
    margin-bottom: 20px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    font-size: 0.95rem;
}

.input-group input, textarea {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-family: 'Inter', sans-serif;
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

textarea {
    font-family: monospace;
    resize: vertical;
    min-height: 150px;
    background-color: #fdfdfd;
}

.input-group input:focus, textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.15);
}

/* BUTTONS */
.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.1s;
    font-family: 'Inter', sans-serif;
}

.btn:active {
    transform: scale(0.98);
}

.btn:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
    background-color: var(--primary-hover);
}

.btn-secondary {
    background-color: var(--secondary-color);
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--secondary-hover);
}

.btn-success {
    background-color: var(--success-color);
    color: white;
}

.btn-success:hover:not(:disabled) {
    background-color: var(--success-hover);
}

.btn-block {
    width: 100%;
}

.actions {
    display: flex;
    justify-content: flex-end;
    gap: 15px;
    margin-top: 25px;
}

/* EXAM HEADER & PROGRESS */
.exam-header {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.student-info-display {
    font-weight: 600;
    color: var(--primary-color);
}

.progress-container {
    flex-grow: 1;
    max-width: 300px;
    height: 10px;
    background-color: var(--border-color);
    border-radius: 5px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background-color: var(--primary-color);
    width: 25%;
    transition: width 0.4s ease;
}

/* EXAM STEPS */
.exam-step {
    display: none;
}
.exam-step.active {
    display: block;
}

/* QCM */
.qcm-question {
    margin-bottom: 20px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}
.qcm-question:last-of-type {
    border-bottom: none;
}
.qcm-question p {
    font-weight: 500;
    margin-bottom: 10px;
}
.qcm-question label {
    display: block;
    margin-bottom: 8px;
    cursor: pointer;
    padding: 8px 12px;
    border-radius: 6px;
    transition: background 0.2s;
}
.qcm-question label:hover {
    background: #f1f3f5;
}
.qcm-question input[type="radio"] {
    margin-right: 10px;
}

/* LOADER */
#submit-loader {
    text-align: center;
    margin-top: 20px;
}
.spinner {
    border: 4px solid rgba(0,0,0,0.1);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border-left-color: var(--primary-color);
    animation: spin 1s linear infinite;
    margin: 0 auto 10px;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* SUCCESS CARD */
.success-card {
    text-align: center;
    padding: 60px 40px;
}
.success-icon {
    font-size: 4rem;
    color: var(--success-color);
    margin-bottom: 20px;
}
.score-display {
    margin: 30px 0;
    padding: 20px;
    background: #f1f8f5;
    border: 1px solid #c3e6cb;
    border-radius: 8px;
    color: #155724;
    font-size: 1.2rem;
}
.success-note {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* RESPONSIVE */
@media (max-width: 600px) {
    .card {
        padding: 20px;
    }
    .exam-header {
        flex-direction: column;
        align-items: flex-start;
    }
    .progress-container {
        max-width: 100%;
        width: 100%;
    }
}