:root {
        --bg-color: #f5fff8;
        --card-bg-color: #ffffff;
        --text-color: #333;
        --primary-color: #2ecc71;
        --secondary-color: #f8f9fa;
        --arabic-font: 'Scheherazade New', 'Amiri', serif;
        --bengali-font: 'Noto Sans Bengali', sans-serif;
        --card-shadow: 0 6px 20px rgba(0, 0, 0, 0.1);
        --filter-sort-bg: #ffffff;
    }

    body.dark-mode {
        --bg-color: #121212;
        --card-bg-color: #1c1c1c;
        --text-color: #e0e0e0;
        --secondary-color: #2a2a2a;
        --card-shadow: 0 6px 20px rgba(0, 0, 0, 0.6);
        --filter-sort-bg: #1e1e1e;
    }

    body {
        background-color: var(--bg-color);
        font-family: var(--bengali-font);
        color: var(--text-color);
        transition: background-color 0.5s, color 0.5s;
    }

    /* ---------- Header ---------- */
    .header {
        background: linear-gradient(135deg, #1f4037, #2ecc71, #99f2c8);
        color: white;
        padding: 70px 0;
        border-bottom-left-radius: 70px;
        border-bottom-right-radius: 70px;
        box-shadow: 0 6px 25px rgba(0,0,0,0.4);
        margin-bottom: 3rem;
        text-align: center;
    }
    .header h1 {
        font-size: 2.5rem;
        font-weight: 700;
        letter-spacing: 1px;
    }
    .header p {
        font-size: 1.2rem;
        opacity: 0.9;
    }

    /* ---------- Surah Card ---------- */
    .card {
        background-color: var(--card-bg-color);
        border: none;
        border-radius: 20px;
        box-shadow: var(--card-shadow);
        transition: transform 0.3s, box-shadow 0.3s, background-color 0.5s;
    }
    .card:hover {
        transform: translateY(-12px);
        box-shadow: 0 12px 35px rgba(46, 204, 113, 0.6);
        border: 2px solid var(--primary-color);
    }

    .surah-number-badge {
        background: linear-gradient(135deg, #27ae60, #2ecc71);
        color: white;
        border-radius: 50%;
        width: 60px;
        height: 60px;
        display: flex;
        align-items: center;
        justify-content: center;
        position: absolute;
        top: -15px;
        left: -15px;
        font-weight: bold;
        font-size: 1.2rem;
        box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    }

    .arabic-name {
        font-family: var(--arabic-font);
        font-size: 1.9rem;
        font-weight: 700;
        color: var(--primary-color);
        margin-top: 12px;
    }

    .card-title {
        font-size: 1.2rem;
        font-weight: 600;
    }

    /* ---------- Filter/Sort/Search Section ---------- */
    .filter-sort-section {
        background-color: var(--filter-sort-bg);
        padding: 25px;
        border-radius: 20px;
        box-shadow: var(--card-shadow);
        margin-bottom: 3rem;
        transition: background-color 0.5s;
    }

    .form-control, .form-select {
        background-color: var(--secondary-color);
        color: var(--text-color);
        border: 1px solid #ddd;
        border-radius: 30px;
        padding: 12px 20px;
        font-size: 1rem;
        transition: all 0.3s;
    }
    .form-control:focus, .form-select:focus {
        border-color: var(--primary-color);
        box-shadow: 0 0 12px rgba(46, 204, 113, 0.5);
    }

    /* ---------- Highlight for Search ---------- */
    .highlight {
        background: #fffa77;
        padding: 0 3px;
        border-radius: 3px;
    }

    /* ---------- Dark/Light Mode Toggle ---------- */
    .mode-toggle {
        position: absolute;
        top: 25px;
        right: 35px;
        font-size: 2.2rem;
        cursor: pointer;
        color: white;
        transition: transform 0.3s;
    }
    .mode-toggle:hover {
        transform: rotate(20deg) scale(1.2);
    }

    /* ---------- Go To Top ---------- */
    .go-to-top {
        background: linear-gradient(135deg, #27ae60, #2ecc71);
        color: white;
        border-radius: 50%;
        width: 60px;
        height: 60px;
        font-size: 28px;
        display: flex;
        align-items: center;
        justify-content: center;
        position: fixed;
        bottom: 30px;
        right: 30px;
        cursor: pointer;
        box-shadow: 0 6px 15px rgba(0,0,0,0.3);
        z-index: 1000;
        transition: opacity 0.4s, transform 0.3s;
        opacity: 0;
        pointer-events: none;
    }
    .go-to-top.show {
        opacity: 1;
        pointer-events: auto;
    }
    .go-to-top:hover {
        transform: scale(1.1);
        box-shadow: 0 8px 20px rgba(0,0,0,0.4);
    }