@import url('https://fonts.googleapis.com/css2?family=Hind+Siliguri:wght@400;500;600;700&display=swap');

:root {
    --bg-color: #f0f2f5;
    --container-bg: #ffffff;
    --text-color: #333333;
    --heading-color-1: #d81b60;
    --heading-color-2: #004d40;
    --heading-color-3: #1a237e;
    --accent-color: #c2185b;
    --blockquote-bg: #e3f2fd;
    --blockquote-border: #2196f3;
    --table-header-bg: #004d40;
    --table-header-text: #ffffff;
    --nav-button-bg: #fff;
    --nav-button-text: #333;
    --nav-button-border: #ccc;
    --nav-active-bg: #d81b60;
    --box-shadow-color: rgba(0, 0, 0, 0.1);
    
    /* MCQ Card Variables */
    --card-border-color: #e0e0e0;
    --card-shadow-color: rgba(0, 0, 0, 0.08);
    --mcq-tag-bg: #007bff;
    --mcq-tag-text: #ffffff;
    --success-color: #28a745;
}

[data-theme="forest"] {
    --bg-color: #f0f4f0; --container-bg: #ffffff; --text-color: #2c3e50; --heading-color-1: #27ae60; --heading-color-2: #16a085; --heading-color-3: #2c3e50; --accent-color: #e67e22; --blockquote-bg: #e8f5e9; --blockquote-border: #27ae60; --table-header-bg: #27ae60;
    --mcq-tag-bg: #27ae60;
}

[data-theme="ocean"] {
    --bg-color: #eef5ff; --container-bg: #ffffff; --text-color: #34495e; --heading-color-1: #2980b9; --heading-color-2: #3498db; --heading-color-3: #1f618d; --accent-color: #e74c3c; --blockquote-bg: #e4f1fe; --blockquote-border: #3498db; --table-header-bg: #2980b9;
    --mcq-tag-bg: #2980b9;
}

[data-theme="sunset"] {
    --bg-color: #fff3e0; --container-bg: #ffffff; --text-color: #4e342e; --heading-color-1: #e65100; --heading-color-2: #f57c00; --heading-color-3: #d84315; --accent-color: #bf360c; --blockquote-bg: #fff8e1; --blockquote-border: #f57c00; --table-header-bg: #e65100;
    --mcq-tag-bg: #e65100;
}

.dark-mode {
    --bg-color: #121212; --container-bg: #1e1e1e; --text-color: #e0e0e0; --heading-color-1: #bb86fc; --heading-color-2: #03dac6; --heading-color-3: #cf6679; --accent-color: #f48fb1; --blockquote-bg: #2a2a2a; --blockquote-border: #03dac6; --table-header-bg: #3700b3; --nav-button-bg: #2c2c2c; --nav-button-text: #e0e0e0; --nav-button-border: #555; --nav-active-bg: #bb86fc; --box-shadow-color: rgba(255, 255, 255, 0.05);
    
    /* MCQ Card Variables for Dark Mode */
    --card-border-color: #444;
    --card-shadow-color: rgba(0, 0, 0, 0.2);
    --mcq-tag-bg: var(--heading-color-1); /* #bb86fc */
    --success-color: #4caf50;
}

html { scroll-behavior: smooth; }
body { font-family: 'Hind Siliguri', sans-serif; background-color: var(--bg-color); color: var(--text-color); line-height: 1.8; margin: 0; padding: 20px; transition: background-color 0.3s, color 0.3s; }
body.desktop-view .container, body.desktop-view header, body.desktop-view .controls-wrapper { max-width: 1200px; }
header { max-width: 900px; margin: 0 auto; display: flex; align-items: center; justify-content: center; flex-direction: column; padding: 20px 0; transition: max-width 0.4s ease-in-out; }
.logo { width: 100px; height: 100px; border-radius: 50%; object-fit: cover; margin-bottom: 15px; box-shadow: 0 4px 12px var(--box-shadow-color); }
.container { max-width: 900px; margin: 20px auto; background-color: var(--container-bg); padding: 30px 40px; border-radius: 12px; box-shadow: 0 4px 12px var(--box-shadow-color); transition: background-color 0.3s, max-width 0.4s ease-in-out; }
h1, h2, h3, h4 { border-bottom: 2px solid var(--card-border-color); padding-bottom: 10px; margin-top: 30px; }
h1 { text-align: center; font-size: 2.2em; color: var(--heading-color-1); border-bottom: none; margin: 0; }
h2 { font-size: 2em; color: var(--heading-color-2); }
h3, h4 { font-size: 1.6em; color: var(--heading-color-3); }
h4 { border-bottom: 1px dotted var(--card-border-color); }
p { font-size: 1.1em; }
strong { color: var(--accent-color); font-weight: 600; }
blockquote { background-color: var(--blockquote-bg); border-left: 5px solid var(--blockquote-border); margin: 20px 0; padding: 15px 20px; font-style: italic; font-size: 1.1em; border-radius: 5px; }
img { max-width: 100%; height: auto; display: block; margin: 25px auto; border-radius: 10px; box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15); }
ol, ul { padding-left: 20px; }
li { margin-bottom: 10px; padding-left: 10px; }
table { width: 100%; border-collapse: collapse; margin: 25px 0; font-size: 1em; }
table th, table td { border: 1px solid var(--nav-button-border); padding: 12px 15px; text-align: left; }
table th { background-color: var(--table-header-bg); color: var(--table-header-text); font-weight: 600; }
table tr:nth-of-type(even) { background-color: var(--blockquote-bg); }
.controls-wrapper { max-width: 900px; margin: 20px auto; padding: 15px; background-color: var(--container-bg); border-radius: 10px; box-shadow: 0 4px 12px var(--box-shadow-color); display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 15px; transition: max-width 0.4s ease-in-out; }
.theme-buttons button, #desktopModeToggle, #rotateScreenToggle { padding: 8px 15px; border: 1px solid var(--nav-button-border); background-color: var(--nav-button-bg); color: var(--nav-button-text); border-radius: 5px; cursor: pointer; font-family: 'Hind Siliguri', sans-serif; font-weight: 600; transition: all 0.2s; }
.theme-buttons button:hover, #desktopModeToggle:hover, #rotateScreenToggle:hover { opacity: 0.8; }
.dark-mode-toggle { display: flex; align-items: center; gap: 10px; }
.switch { position: relative; display: inline-block; width: 60px; height: 34px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: #ccc; transition: .4s; border-radius: 34px; }
.slider:before { position: absolute; content: ""; height: 26px; width: 26px; left: 4px; bottom: 4px; background-color: white; transition: .4s; border-radius: 50%; }
input:checked + .slider { background-color: var(--heading-color-1); }
input:checked + .slider:before { transform: translateX(26px); }
.digital-clock { font-family: 'Courier New', Courier, monospace; font-size: 1.2em; font-weight: bold; padding: 8px 15px; background-color: var(--blockquote-bg); border: 1px solid var(--blockquote-border); border-radius: 5px; color: var(--heading-color-1); }
.navigation { text-align: center; margin-top: 40px; padding-top: 20px; border-top: 2px solid #eee; display: flex; justify-content: center; align-items: center; flex-wrap: wrap; gap: 10px; }
.dark-mode .navigation { border-top-color: #333; }
.nav-button { display: inline-block; padding: 10px 15px; border: 1px solid var(--nav-button-border); border-radius: 5px; text-decoration: none; color: var(--nav-button-text); background-color: var(--nav-button-bg); transition: background-color 0.3s, color 0.3s; font-weight: 500; }
.nav-button:hover { background-color: #e0e0e0; }
.dark-mode .nav-button:hover { background-color: #3a3a3a; }
.nav-button.active { background-color: var(--nav-active-bg); color: white; border-color: var(--nav-active-bg); }
.nav-button.disabled { pointer-events: none; opacity: 0.5; }
.home-button { background-color: #1e88e5; color: white; border-color: #1e88e5; }
.home-button:hover { background-color: #1565c0; }
footer { text-align: center; margin-top: 40px; padding: 20px; font-size: 0.9em; color: var(--text-color); opacity: 0.8; }
.scroll-button { position: fixed; bottom: 20px; right: 20px; width: 50px; height: 50px; border-radius: 50%; background-color: var(--heading-color-1); color: white; border: none; font-size: 24px; cursor: pointer; display: none; justify-content: center; align-items: center; box-shadow: 0 4px 8px rgba(0,0,0,0.2); z-index: 1000; transition: opacity 0.3s, visibility 0.3s; }
#scrollToBottomBtn { bottom: 80px; background-color: var(--heading-color-2); }
.scroll-button:hover { opacity: 0.8; }

/* =================================
   Modern MCQ Card Style (আধুনিক কার্ড ডিজাইন)
   ================================= */

.question-item {
    background-color: var(--container-bg);
    border: 1px solid var(--card-border-color);
    border-radius: 12px;
    padding: 50px 25px 25px 25px; /* উপরের দিকে ট্যাগের জন্য জায়গা */
    margin-bottom: 30px;
    box-shadow: 0 4px 12px var(--card-shadow-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    position: relative; /* h3 ট্যাগকে পজিশন করার জন্য */
    overflow: hidden; /* ট্যাগের বর্ডার-রেডিয়াস ঠিকভাবে দেখানোর জন্য */
}

.question-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px var(--card-shadow-color);
}

/* প্রশ্নের নম্বর ট্যাগ (e.g., প্রশ্ন ২৭) */
.question-item h3 {
    position: absolute;
    top: 0;
    left: 0;
    background-color: var(--mcq-tag-bg);
    color: var(--mcq-tag-text);
    padding: 8px 20px;
    border-radius: 12px 0 12px 0; /* স্টাইলিশ কর্নার */
    font-weight: bold;
    font-size: 1rem;
    
    /* বেস h3 স্টাইল ওভাররাইড */
    border-bottom: none;
    margin: 0;
}

/* প্রশ্নের মূল টেক্সট */
.question-item > p:first-of-type {
    font-size: 1.2em;
    font-weight: 500;
    margin-top: 0;
    margin-bottom: 20px;
}
.question-item > p:first-of-type strong {
    color: var(--text-color);
}

/* অপশনের তালিকা (ul এবং li) */
.question-item ul {
    list-style-type: none;
    padding: 0;
    margin: 0 0 20px 0;
}

.question-item ul li {
    font-size: 1.1em;
    padding: 12px 15px;
    border-bottom: 1px dashed var(--card-border-color);
    transition: background-color 0.2s;
    border-radius: 6px;
}

.question-item ul li:last-child {
    border-bottom: none;
}

.question-item ul li:hover {
    background-color: var(--blockquote-bg);
    cursor: pointer;
}

/* উত্তর এবং ব্যাখ্যা সেকশন */
.answer-section .answer-divider {
    border: 0;
    height: 1px;
    background-color: var(--card-border-color);
    margin: 15px 0;
}

.answer-section p {
    font-size: 1.1em;
}

.answer-section .answer-label {
    color: var(--accent-color);
}

.answer-section .correct-answer {
    color: var(--success-color);
    font-weight: bold;
    background-color: var(--blockquote-bg);
    padding: 2px 8px;
    border-radius: 4px;
}

/* ব্যাখ্যা বক্স */
.explanation {
    margin-top: 15px;
    padding: 15px;
    background-color: var(--blockquote-bg);
    border-left: 4px solid var(--blockquote-border);
    border-radius: 4px;
}
.explanation p {
    margin: 0;
    font-size: 1em;
}