.site-footer {
    background-color: #1a1a2e;
    color: #ccc;
    padding: 40px 20px 20px;
    font-size: .95rem;
    margin-top: 60px
}

.footer-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    max-width: 1200px;
    margin: auto;
    gap: 20px
}

.footer-left {
    flex: 1;
    min-width: 250px
}

    .footer-left h4 {
        color: #fff;
        font-size: 1.2rem;
        margin-bottom: 10px
    }

.footer-links ul {
    list-style: none;
    padding: 0
}

.footer-links li {
    margin-bottom: 6px
}

.footer-links a {
    color: #bbb;
    text-decoration: none
}

    .footer-links a:hover {
        color: #fff;
        text-decoration: underline
    }

.footer-social {
    min-width: 200px
}

    .footer-social a {
        display: block;
        color: #bbb;
        text-decoration: none;
        margin-bottom: 6px
    }

        .footer-social a:hover {
            color: #fff;
            text-decoration: underline
        }

.footer-bottom {
    border-top: 1px solid #333;
    text-align: center;
    padding-top: 15px;
    font-size: .85rem;
    color: #999;
    margin-top: 20px
}

@media screen and (max-width:768px) {
    .footer-container {
        flex-direction: column;
        text-align: center
    }

    .footer-social a {
        display: inline-block;
        margin: 0 8px
    }
}

body.light-mode {
    background-color: #fff;
    color: #000;
    --welcome-bg: #f5f9ff
}

body.dark-mode {
    background-color: #1e1e2f;
    color: #f0f0f0;
    --welcome-bg: #2a2a40
}

.welcome-section {
    padding: 30px;
    border-radius: 16px;
    text-align: center;
    transition: background-color .3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: var(--welcome-bg);
    box-shadow: 0 4px 12px rgba(0,0,0,.1);
    gap: 20px
}

body.light-mode .welcome-section {
    background-color: #f5f9ff;
    color: #000;
    box-shadow: 0 4px 8px rgba(0,0,0,.1)
}

body.dark-mode .welcome-section {
    background-color: #2c2c3c;
    color: #fff;
    box-shadow: 0 4px 12px rgba(0,0,0,.6)
}

.welcome-section h1 {
    font-size: 2.8rem;
    font-weight: 700;
    margin-bottom: 10px
}

body.dark-mode .welcome-section h1 {
    color: #fff;
    text-shadow: none
}

.welcome-section p {
    font-size: 1.1rem;
    line-height: 1.6;
    margin-bottom: .75rem
}

body.dark-mode .welcome-section p {
    color: #ddd;
    text-shadow: none
}

body.dark-mode .answer {
    background-color: #2a2a40;
    color: #f5f5f5;
    padding: 10px 14px;
    margin: 8px 0 14px;
    border-radius: 8px;
    font-size: 1rem;
    box-shadow: 0 0 4px rgba(0,0,0,.3)
}

    body.dark-mode .tab-contents, body.dark-mode .question, body.dark-mode .sub-tab-content, body.dark-mode .answer button {
        color: #f0f0f0 !important;
        background-color: #2a2a40;
        border-color: #444
    }

.question {
    font-weight: 700;
    cursor: pointer;
    margin-top: 10px
}

.answer {
    margin-left: 15px;
    margin-bottom: 10px
}

.welcome-text {
    color: inherit
}

.tab-button {
    flex: 1;
    padding: 12px 0;
    border: 0;
    background: linear-gradient(to right,#e0eafc,#cfdef3);
    color: #333;
    font-weight: 500;
    font-size: 14px;
    text-align: center;
    border-radius: 50px;
    box-shadow: 0 2px 4px rgba(0,0,0,.1);
    transition: background .3s,color .3s,transform .2s;
    cursor: pointer
}

    .tab-button:hover {
        background: linear-gradient(to right,#d4fc79,#96e6a1);
        transform: translateY(-1px)
    }

    .tab-button.active {
        background: linear-gradient(to right,#667eea,#764ba2);
        color: #fff;
        box-shadow: 0 4px 6px rgba(0,0,0,.15)
    }

.welcome-banner-image img {
    width: 120px;
    height: auto;
    border-radius: 10px;
    margin-bottom: 10px
}

.welcome-banner-text h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: inherit
}

.welcome-banner-text .welcome-text {
    font-size: 1.1rem;
    line-height: 1.5;
    color: inherit;
    margin: .3rem 0
}

.keywords {
    margin-top: 15px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px
}

    .keywords span {
        font-size: .9rem;
        font-weight: 700;
        background-color: #007bff;
        color: #fff;
        padding: 6px 12px;
        border-radius: 16px;
        box-shadow: 0 2px 6px rgba(0,123,255,.4);
        transition: background-color .3s
    }

body.dark-mode .keywords span {
    background-color: #ff6f61;
    box-shadow: 0 2px 6px rgba(255,111,97,.4)
}

.mode-toggle {
    margin-bottom: 10px;
    justify-content: flex-start;
    display: flex;
    align-items: flex-start
}

.mode-btn {
    flex: 1;
    padding: 12px 0;
    border: 0;
    background: linear-gradient(to right,#e0eafc,#cfdef3);
    color: #333;
    font-weight: 600;
    font-size: 16px;
    text-align: center;
    border-radius: 50px;
    box-shadow: 0 2px 4px rgba(0,0,0,.1);
    transition: background .3s,color .3s,transform .2s;
    cursor: pointer
}

    .mode-btn.active {
        background: linear-gradient(to right,#667eea,#764ba2);
        color: #fff;
        box-shadow: 0 4px 6px rgba(0,0,0,.15)
    }

    .mode-btn:hover {
        background: linear-gradient(to right,#d4fc79,#96e6a1);
        transform: translateY(-1px)
    }

.page-title {
    font-size: 2rem;
    font-weight: 700;
    color: #4a4a4a;
    margin-bottom: 1.5rem;
    text-align: center
}

#topic-sections {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    padding: 1rem
}

.topic-section {
    background: #fff;
    padding: 1.2rem 1.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 10px rgba(0,0,0,.07);
    border-left: 6px solid #5c6bc0;
    transition: transform .2s
}

    .topic-section:hover {
        transform: translateY(-2px)
    }

    .topic-section h3 {
        font-size: 1.4rem;
        margin-bottom: .8rem;
        color: #3f51b5
    }

    .topic-section p, .topic-section ul, .topic-section li {
        font-size: 1rem;
        color: #333;
        line-height: 1.6
    }

    .topic-section ul {
        list-style: disc;
        margin-left: 1.2rem
    }

pre code {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 1rem;
    display: block;
    border-radius: 10px;
    overflow-x: auto;
    font-size: .9rem
}

.pdf-download-btn {
    background: linear-gradient(to right,#00c6ff,#0072ff);
    color: #fff;
    padding: 12px 20px;
    border: 0;
    border-radius: 50px;
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0,0,0,.2);
    transition: background .3s ease
}

    .pdf-download-btn:hover {
        background: linear-gradient(to right,#0072ff,#00c6ff)
    }

@media(max-width:768px) {
    .topic-section h3 {
        font-size: 1.2rem
    }

    .topic-section p, .topic-section ul, .topic-section li {
        font-size: .95rem
    }

    pre code {
        font-size: .8rem
    }

    .pdf-download-btn {
        font-size: .9rem;
        padding: 10px 16px
    }
}

body {
    background: linear-gradient(to bottom right,#f1f4f9,#dff1ff);
    font-family: 'Segoe UI',sans-serif
}

.mcq-question ul {
    list-style: none;
    padding-left: 0
}

.mcq-question li {
    padding: 10px;
    margin-bottom: 5px;
    background-color: #f4f4f4;
    border-radius: 8px;
    cursor: pointer;
    transition: .3s;
    border: 1px solid #ccc
}

    .mcq-question li:hover {
        background-color: #e2e2ff
    }

    .mcq-question li.correct {
        background-color: #c8f7c5;
        border-color: #008000;
        font-weight: 700
    }

    .mcq-question li.wrong {
        background-color: #f8d7da;
        border-color: #f00
    }

    .mcq-question li.disabled {
        opacity: .6;
        pointer-events: none
    }

.modal-content {
    background: linear-gradient(to right,#f8f9fa,#fff);
    padding: 30px 25px;
    width: 90%;
    max-width: 460px;
    border-radius: 16px;
    text-align: center;
    box-shadow: 0 8px 20px rgba(0,0,0,.2);
    animation: fadeIn .4s ease-in-out;
    color: #212529
}

    .modal-content h3, .modal-content p, .modal-content label {
        color: #212529
    }

    .modal-content input, .modal-content textarea {
        width: 100%;
        padding: 10px 12px;
        margin: 8px 0;
        font-size: 14px;
        border: 1px solid #ccc;
        border-radius: 8px;
        outline: 0;
        transition: border-color .3s
    }

        .modal-content input:focus, .modal-content textarea:focus {
            border-color: #4a90e2
        }

    .modal-content button {
        background-color: #007bff;
        color: #fff;
        border: 0;
        padding: 10px 20px;
        font-size: 14px;
        border-radius: 8px;
        margin-top: 10px;
        cursor: pointer;
        transition: background .3s ease
    }

        .modal-content button:hover {
            background-color: #0056b3
        }

ul {
    list-style: none;
    padding-left: 0
}

    ul li {
        margin: 8px 0
    }

        ul li a {
            text-decoration: underline;
            color: #007bff
        }

.hidden {
    display: none
}

body.dark-mode .modal-content {
    background: linear-gradient(to right,#1f1f1f,#2b2b2b);
    color: #f1f1f1
}

    body.dark-mode .modal-content h3, body.dark-mode .modal-content p, body.dark-mode .modal-content label {
        color: #f1f1f1
    }

    body.dark-mode .modal-content input, body.dark-mode .modal-content textarea {
        background-color: #333;
        color: #eee;
        border: 1px solid #555
    }

        body.dark-mode .modal-content input:focus, body.dark-mode .modal-content textarea:focus {
            border-color: #80bdff
        }

body.dark-mode ul li a {
    color: #66b3ff
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(.9)
    }

    to {
        opacity: 1;
        transform: scale(1)
    }
}

.tabs-container {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
    gap: 10px
}

nav a {
    padding: .5rem 1rem;
    color: #333;
    font-weight: 500;
    text-decoration: none
}

    nav a:hover, nav a.active {
        border-bottom: 2px solid #007bff;
        color: #007bff
    }

.tabs-containers > button:not(:last-child) {
    border-right: 1.5px solid rgba(255,255,255,.3);
    border-left: 1.5px solid rgba(255, 255, 255, .3);
    padding-right: 1rem;
    margin-right: 1rem
}

.breadcrumb-custom a {
    transition: color .2s ease
}

    .breadcrumb-custom a:hover {
        color: #2563eb;
        text-decoration: underline
    }

.breadcrumb-custom span {
    margin: 0 4px;
    font-weight: 500
}

@media(max-width:768px) {
    .breadcrumb-custom {
        justify-content: center !important;
        text-align: center;
        flex-direction: row
    }
}

.nested-tabs, .sub-tab-content {
    margin-left: 0;
    margin-top: 10px
}

.nested-tabs {
    display: flex;
    gap: 10px
}

.question {
    background-color: #f0f8ff;
    padding: 10px;
    margin-top: 10px;
    cursor: pointer;
    font-weight: 700;
    border-radius: 4px
}

.answer {
    display: none;
    padding: 10px;
    border-left: 3px solid #007bff;
    background-color: #fafafa;
    margin-bottom: 10px;
    border-radius: 4px
}

.tabs-containers {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
    gap: 10px
}

.tab-buttons, .tab-button {
    flex: 1;
    padding: 12px 0;
    border: 0;
    background: linear-gradient(to right,#e0eafc,#cfdef3);
/*    color: #333;
*/    text-align: center;
    border-radius: 50px;
    box-shadow: 0 2px 4px rgba(0,0,0,.1);
    transition: background .3s,color .3s,transform .2s;
    cursor: pointer
}

.tab-buttons {
    font-weight: 600;
    font-size: 16px
}

    .tab-buttons:hover, .tab-button:hover {
        background: linear-gradient(to right,#d4fc79,#96e6a1);
        transform: translateY(-1px)
    }

    .tab-buttons.active, .tab-button.active {
        background: linear-gradient(to right,#667eea,#764ba2);
        color: #fff;
        box-shadow: 0 4px 6px rgba(0,0,0,.15)
    }

.tab-button {
    font-weight: 500;
    font-size: 14px
}

.top-tab {
    border-radius: 10px;
    background: linear-gradient(to right,#6a11cb,#2575fc);
    color: #fff;
    padding: 10px;
    margin: 0 10px;
    font-weight: 700;
    box-shadow: 0 4px 12px rgba(0,0,0,.1);
    transition: all .3s ease
}

    .top-tab:hover, .top-tab.active {
        background: linear-gradient(to right,#533ce1,#1f75e8);
        transform: scale(1.05)
    }

.mode-toggle-container {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-left: auto;
    font-weight: 500;
    font-size: .95rem
}

.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 24px
}

    .switch input {
        opacity: 0;
        width: 0;
        height: 0
    }

.slider {
    position: absolute;
    cursor: pointer;
    background-color: #ccc;
    border-radius: 34px;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    transition: .4s
}

    .slider:before {
        content: "";
        position: absolute;
        height: 18px;
        width: 18px;
        left: 3px;
        bottom: 3px;
        background-color: #fff;
        border-radius: 50%;
        transition: .4s
    }

input:checked + .slider {
    background-color: #6c5ce7
}

    input:checked + .slider:before {
        transform: translateX(26px)
    }

.mode-description {
    margin: 0;
    font-size: 16px;
    color: #333;
    max-width: 700px
}

body.light-mode {
    background: linear-gradient(to bottom right,#f1f4f9,#dff1ff);
    color: #1a1a1a
}

body.dark-mode {
    background: #1e1e2f;
    color: #f0f0f0
}

    body.dark-mode .topic-section {
        background-color: #2b2c3a;
        border-left-color: #9c27b0
    }

        body.dark-mode .topic-section h3 {
            color: #f06292
        }

    body.dark-mode .pdf-download-btn {
        background: linear-gradient(to right,#4caf50,#388e3c)
    }

        body.dark-mode .pdf-download-btn:hover {
            background: linear-gradient(to right,#66bb6a,#43a047)
        }

    body.dark-mode pre code {
        background-color: #121212;
        color: #b0f0ff
    }

    body.dark-mode h1, body.dark-mode h2, body.dark-mode h3, body.dark-mode h4, body.dark-mode h5, body.dark-mode h6 {
        color: #fff
    }

    body.dark-mode p, body.dark-mode li, body.dark-mode strong, body.dark-mode span {
        color: #e0e0e0;
        text-shadow: 0 1px 2px rgba(0,0,0,.5)
    }

    body.dark-mode .mode-btn {
        background: #2c2c3c;
        color: #e0e0e0
    }

        body.dark-mode .mode-btn.active {
            background: linear-gradient(to right,#3f51b5,#9c27b0);
            color: #fff
        }

    body.dark-mode .topic-section {
        background: #2b2c3a;
        border-left-color: #7e57c2
    }

    body.dark-mode .mcq-question {
        background-color: #2a2a40;
        color: #f5f5f5;
        padding: 14px;
        margin: 12px 0;
        border-radius: 10px;
        box-shadow: 0 0 6px rgba(0,0,0,.3)
    }

        body.dark-mode .mcq-question ul {
            list-style: none;
            padding-left: 0
        }

        body.dark-mode .mcq-question li {
            background-color: #3a3a50;
            color: #f0f0f0;
            margin: 8px 0;
            padding: 10px 14px;
            border-radius: 8px;
            cursor: pointer;
            transition: background-color .2s ease
        }

            body.dark-mode .mcq-question li:hover {
                background-color: #505070
            }

.mcq-correct {
    background-color: #4caf50 !important;
    color: #fff !important
}

.mcq-wrong {
    background-color: #f44336 !important;
    color: #fff !important
}