:root {
    --primary-color: #4B352A;
    --secondary-color: #EAD8A4;
    --unit-color: #5A827E;
    --accent-color: #A0C878;
    --light-color: #FDFAF6;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --text-color: #4B352A;
    --hover-scale: 1.05;
    --background-color: #FDFAF6;
}

.main-container {
    max-width: 2500px;
    margin: 120px auto 60px auto;
    padding: 30px;
    background-color: var(--background-color);
    border-radius: 20px;
    box-shadow: 0 6px 20px var(--shadow-color);
    position: relative;
    transition: all 0.3s ease;
    margin-bottom: 200px;
}

.selection-container {
    max-width: 800px;
    margin: 50px auto;
    padding: 30px;
    background-color: var(--background-color);
    border-radius: 20px;
    box-shadow: 0 6px 20px var(--shadow-color);
    text-align: center;
    transition: all 0.3s ease;
}

.selection-container h1 {
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: 2.5rem;
}

.mode-selector {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
    gap: 20px;
}

.mode-button{
    padding: 12px 25px;
    border: none;
    border-radius: 20px;
    background-color: var(--light-color);
    color: var(--primary-color);
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1rem;
    box-shadow: 0 4px 8px var(--shadow-color);
}

.mode-button:hover {
    background-color: var(--accent-color);
    transform: scale(var(--hover-scale));
}

.mode-button.active {
    background-color: var(--secondary-color);
    color: var(--background-color);
}

.unit-chapter-selector {
    display: flex;
    flex-direction: column;
    gap: 30px;
    margin-bottom: 30px;
}

.unit-selector, .chapter-selector {
    background-color: var(--light-color);
    padding: 25px;
    border-radius: 20px;
    box-shadow: 0 4px 15px var(--shadow-color);
    transition: all 0.3s ease;
}

.unit-selector h2, .chapter-selector h2 {
    margin-top: 0;
    color: var(--unit-color);
    font-size: 1.5rem;
    margin-bottom: 20px;
}

.unit-buttons, .chapter-buttons, .book-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 15px;
}

.unit-button, .chapter-button, .book-button {
    padding: 12px 25px;
    border: none;
    border-radius: 20px;
    background-color: var(--light-color);
    color: var(--primary-color) !important; 
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1rem;
    box-shadow: 0 4px 8px var(--shadow-color);
}

.unit-button:hover, .chapter-button:hover, .book-button:hover {
    background-color: var(--accent-color);
    transform: scale(var(--hover-scale));
}

.unit-button.active, .chapter-button.active, .book-button.active {
    background-color: var(--unit-color);
    color: var(--background-color);
}

.start-exercise-button {
    padding: 18px 35px;
    border: none;
    border-radius: 20px;
    background-color: var(--secondary-color);
    color: var(--background-color);
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 30px;
    font-size: 1.1rem;
    box-shadow: 0 6px 15px var(--shadow-color);
}

.start-exercise-button:hover {
    background-color: var(--primary-color);
    transform: scale(var(--hover-scale));
}

.exercise-container {
    max-width: 800px;
    margin: 40px auto;
    padding: 30px;
    background-color: var(--background-color);
    border-radius: 20px;
    box-shadow: 0 6px 20px var(--shadow-color);
    display: none;
    transition: all 0.3s ease;
}

.exercise {
    margin-bottom: 30px;
}

.exercise h2 {
    color: var(--unit-color);
    margin-bottom: 20px;
    font-size: 1.8rem;
}

.exercise p {
    font-size: 1.1rem;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.exercise input[type="text"], input {
    width: 100%;
    padding: 15px;
    margin-bottom: 20px;
    border: 2px solid #ddd;
    border-radius: 10px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
    box-sizing: border-box;
}

.exercise input[type="text"]:focus, input:focus {
    border-color: var(--unit-color);
    outline: none;
}

.check-button {
    padding: 12px 25px;
    border: none;
    border-radius: 20px;
    background-color: var(--secondary-color);
    color: var(--background-color);
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1rem;
    box-shadow: 0 4px 8px var(--shadow-color);
}

.check-button:hover {
    background-color: var(--primary-color);
    transform: scale(var(--hover-scale));
}

.feedback-box {
    background: #fff;
    border-radius: 20px;
    box-shadow: 0 4px 16px var(--shadow-color);
    padding: 20px 30px;
    margin-bottom: 25px;
    text-align: left;
}

.motivation-box {
    background: #e6ffe6;
    border-radius: 12px;
    padding: 18px;
    box-shadow: 0 2px 8px #b2f2b2;
    margin-bottom: 25px;
    font-size: 1.2em;
    text-align: center;
}

/* Background Animation */
.bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    z-index: -1;
    opacity: 0.6;
}

.bg2 {
    background: linear-gradient(135deg, #e0eafc 0%, #cfdef3 100%);
    animation: slide 15s infinite;
}

.bg3 {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    animation: slide 20s infinite;
}

@keyframes slide {
    0% {
        transform: translateY(-100%);
    }
    100% {
        transform: translateY(100%);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .main-container {
        margin: 100px 20px 40px;
        padding: 20px;
    }

    .selection-container {
        margin: 30px 20px;
        padding: 20px;
    }

    .unit-buttons, .chapter-buttons {
        gap: 10px;
    }

    .mode-selector {
        flex-direction: column;
        gap: 15px;
    }

    header {
        padding: 10px 20px;
    }

    .linksOben {
        gap: 10px;
    }

    .title {
        font-size: 1.5rem;
    }
}

form input[type="password"] {
    width: 100%;
    padding: 15px;
    border: 2px solid #ddd;
    border-radius: 10px;
    font-size: 1rem;
    box-sizing: border-box;
    background-color: var(--light-color);
    color: var(--primary-color);
    box-shadow: 0 4px 8px var(--shadow-color);
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
    outline: none;
    margin-bottom: 20px;
}

form input[type="password"]:focus {
    border-color: var(--unit-color);
    box-shadow: 0 0 10px var(--unit-color);

}