/* ===========================
   RESET
=========================== */

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

html{
    scroll-behavior:smooth;
}

body{
    font-family:'Hind Siliguri',sans-serif;
    color:#325479;
    background:#ffffff;
    line-height:1.7;
}

img{
    max-width:100%;
    display:block;
}

a{
    text-decoration:none;
    color:inherit;
}

ul{
    list-style:none;
}

/* ===========================
   CONTAINER
=========================== */

.container{
    width:95%;
    max-width:1200px;
    margin:auto;
}

/* ===========================
   BUTTONS
=========================== */

.btn{
    display:inline-flex;
    align-items:center;
    justify-content:center;
    gap:10px;
    padding:14px 28px;
    border-radius:12px;
    font-weight:600;
    transition:.3s;
}

.btn-primary{
    background:#0ea5e9;
    color:#fff;
}

.btn-primary:hover{
    background:#0284c7;
}

.btn-dark{
    background:#0f172a;
    color:#fff;
}

.btn-dark:hover{
    background:#1e293b;
}

.btn-outline{
    border:2px solid #dbeafe;
    color:#334155;
}

.btn-outline:hover{
    background:#eff6ff;
}

/* ===========================
   HEADER
=========================== */

.header{

    position:sticky;
    top:0;
    z-index:999;

    background:#fff;

    border-bottom:1px solid #eee;

    backdrop-filter:blur(10px);

}

.header .container{

    display:flex;

    justify-content:space-between;

    align-items:center;

    height:80px;

}

.logo{

    display:flex;

    align-items:center;

    gap:12px;

}

.logo img{

    height:55px;

}

.logo span{

    font-weight:700;

    color:#0284c7;

}

.navbar ul{

    display:flex;

    gap:35px;

}

.navbar a{

    font-weight:600;

    transition:.3s;

}

.navbar a:hover{

    color:#0ea5e9;

}

.menu-btn{

    display:none;

    background:none;

    border:none;

    font-size:24px;

}

/* ===========================
   HERO
=========================== */

.hero{

    padding:80px 0;

}

.hero-grid{

    display:grid;

    grid-template-columns:repeat(2,1fr);

    gap:70px;

    align-items:center;

}

.badge{

    display:inline-flex;

    align-items:center;

    gap:10px;

    background:#e0f2fe;

    color:#0369a1;

    padding:10px 18px;

    border-radius:50px;

    margin-bottom:25px;

    font-weight:600;

}

.badge i{

    font-size:10px;

}

.hero h1{

    font-size:55px;

    line-height:1.2;

    margin-bottom:25px;

}

.hero h1 span{

    color:#0ea5e9;

}

.hero p{

    color:#64748b;

    margin-bottom:35px;

}

.hero-buttons{

    display:flex;

    gap:20px;

    margin-bottom:45px;

}

.hero-stats{

    display:flex;

    justify-content:space-between;

    border-top:1px solid #e2e8f0;

    padding-top:30px;

}

.hero-stats h3{

    font-size:32px;

    color:#0f172a;

}

.hero-stats p{

    margin-top:5px;

    color:#64748b;

}

/* ===========================
   HERO CARD
=========================== */

.hero-card{

    background:#0f172a;

    color:#fff;

    border-radius:25px;

    padding:35px;

    box-shadow:0 20px 50px rgba(0,0,0,.2);

}

.window-header{

    display:flex;

    gap:8px;

    margin-bottom:30px;

}

.window-header span{

    width:12px;

    height:12px;

    border-radius:50%;

}

.red{

    background:#ef4444;

}

.yellow{

    background:#facc15;

}

.green{

    background:#22c55e;

}

.code-area{

    font-family:monospace;

}

.green-text{

    color:#22c55e;

}

.formula{

    margin:25px 0;

    padding:18px;

    background:#020617;

    border-radius:12px;

    text-align:center;

    font-size:18px;

}

.tip{

    color:#94a3b8;

}

/* ===========================
   ABOUT
=========================== */

.about{

    padding:100px 0;

    background:#fff;

}

.about-grid{

    display:grid;

    grid-template-columns:1fr 1fr;

    gap:70px;

    align-items:center;

}

.teacher-image img{

    border-radius:25px;

}

.section-tag{

    display:inline-block;

    color:#0284c7;

    font-weight:700;

    margin-bottom:20px;

}

.about h2{

    font-size:42px;

    margin-bottom:25px;

}

.about p{

    color:#64748b;

    margin-bottom:20px;

}

.teacher-info{

    display:flex;

    gap:40px;

    margin-top:30px;

}

.teacher-info div{

    display:flex;

    gap:10px;

    align-items:center;

    font-weight:600;

}

.teacher-info i{

    color:#0ea5e9;

}

/* ===========================
   SECTION HEADER
=========================== */

.section-header{

    text-align:center;

    margin-bottom:60px;

}

.section-header h2{

    font-size:40px;

    margin:15px 0;

}

.section-header p{

    color:#64748b;

}

/* ===========================
   RESPONSIVE
=========================== */

@media(max-width:992px){

.hero-grid,
.about-grid{

grid-template-columns:1fr;

}

.navbar{

display:none;

}

.menu-btn{

display:block;

}

.hero{

text-align:center;

}

.hero-buttons{

justify-content:center;

}

}

@media(max-width:768px){

.hero h1{

font-size:38px;

}

.hero-buttons{

flex-direction:column;

}

.hero-stats{

flex-direction:column;

gap:30px;

text-align:center;

}

.about h2{

font-size:32px;

}

}

/* ===========================
   COURSES SECTION
=========================== */

.courses{
    padding:100px 0;
    background:#f8fafc;
}

.course-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit,minmax(320px,1fr));
    gap:35px;
}

.course-card{
    background:#fff;
    border-radius:20px;
    padding:35px;
    position:relative;
    box-shadow:0 10px 30px rgba(0,0,0,.08);
    transition:.3s;
}

.course-card:hover{
    transform:translateY(-8px);
    box-shadow:0 20px 40px rgba(0,0,0,.12);
}

.course-card.featured{
    border:3px solid #0ea5e9;
}

.popular{
    position:absolute;
    top:18px;
    right:18px;
    background:#ef4444;
    color:#fff;
    padding:6px 12px;
    border-radius:30px;
    font-size:13px;
    font-weight:600;
}

.course-badge{
    display:inline-block;
    background:#e0f2fe;
    color:#0284c7;
    padding:8px 16px;
    border-radius:30px;
    font-size:14px;
    font-weight:600;
    margin-bottom:20px;
}

.course-card h3{
    margin-bottom:15px;
    font-size:28px;
}

.course-card p{
    color:#64748b;
    margin-bottom:20px;
}

.course-card ul{
    margin-bottom:30px;
}

.course-card li{
    display:flex;
    align-items:center;
    gap:10px;
    margin-bottom:12px;
}

.course-card li i{
    color:#22c55e;
}

.course-footer{
    display:flex;
    justify-content:space-between;
    align-items:left;
    border-top:1px solid #e2e8f0;
    padding-top:25px;
}

.course-footer h4{
    color:#0ea5e9;
    font-size:26px;
}

/* ===========================
   PLAYLIST SECTION
=========================== */

.playlist-section{
    
    background:#020617;

    color:#94a3b8;

    padding:70px 0 25px;
}

.playlist-tabs{
    display:flex;
    justify-content:center;
    gap:15px;
    flex-wrap:wrap;
    margin-bottom:50px;
}

.playlist-tabs button{
    padding:12px 24px;
    border:none;
    border-radius:30px;
    background:#e2e8f0;
    cursor:pointer;
    font-weight:600;
    transition:.3s;
}

.playlist-tabs button.active,
.playlist-tabs button:hover{
    background:#0ea5e9;
    color:#fff;
}

.playlist-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit,minmax(280px,1fr));
    gap:30px;
}

.video-card{
    background:#fff;
    border-radius:18px;
    overflow:hidden;
    box-shadow:0 10px 25px rgba(0,0,0,.08);
    transition:.3s;
   
}

.video-card:hover{
    transform:translateY(-6px);
}

.video-card img{
    width:100%;
    aspect-ratio:16/9;
    object-fit:contain;
}

.video-card h4{
    padding:20px;
    font-size:22px;
}

.video-card a{
    display:block;
    text-align:center;
    background:#0ea5e9;
    color:#fff;
    padding:16px;
    font-weight:600;
    transition:.3s;
}

.video-card a:hover{
    background:#0284c7;
}

/* ===========================
   TESTIMONIAL
=========================== */

.testimonial{
    padding:100px 0;
    background:#f8fafc;
}

.testimonial-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit,minmax(300px,1fr));
    gap:30px;
}

.testimonial-card{
    background:#fff;
    padding:35px;
    border-radius:20px;
    box-shadow:0 8px 25px rgba(0,0,0,.08);
    transition:.3s;
}

.testimonial-card:hover{
    transform:translateY(-6px);
}

.testimonial-card p{
    font-size:18px;
    color:#475569;
    margin-bottom:25px;
    font-style:italic;
}

.testimonial-card h4{
    color:#0ea5e9;
    font-weight:700;
}

/* ===========================
   FAQ
=========================== */

.faq{
    padding:100px 0;
}

.faq-item{
    background:#fff;
    border:1px solid #e2e8f0;
    border-radius:16px;
    margin-bottom:20px;
    padding:25px 30px;
    transition:.3s;
}

.faq-item:hover{
    box-shadow:0 10px 25px rgba(0,0,0,.08);
}

.faq-item h3{
    margin-bottom:12px;
    font-size:22px;
    color:#0f172a;
}

.faq-item p{
    color:#64748b;
}

/*==================================
            FOOTER
==================================*/

.footer{

        background:#020617;

        color:#94a3b8;

        padding:70px 0 25px;

        border-top:1px solid #1e293b;

    }

    .footer-top{

        display:grid;

        grid-template-columns:repeat(3,1fr);

        gap:50px;

        padding-bottom:40px;

        border-bottom:1px solid #1e293b;

    }

    .footer-logo{

        width:170px;

        margin-bottom:20px;

    }

    .footer-box h3{

        color:#fff;

        font-size:15px;

        text-transform:uppercase;

        letter-spacing:1px;

        margin-bottom:20px;

    }

    .footer-box p{

        color:#94a3b8;

        line-height:1.8;

        font-size:15px;

    }

    .footer-box ul{

        list-style:none;

    }

    .footer-box ul li{

        margin-bottom:15px;

        color:#94a3b8;

        font-size:15px;

    }

    .footer-box ul li i{

        color:#0ea5e9;

        width:25px;

    }

    .footer-bottom{

        display:flex;

        justify-content:space-between;

        align-items:center;

        flex-wrap:wrap;

        padding-top:25px;

        gap:20px;

    }

    .footer-bottom p{

        color:#64748b;

        font-size:14px;

    }

    .footer-links{

        display:flex;

        gap:25px;

    }

    .footer-links a{

        color:#64748b;

        text-decoration:none;

        transition:.3s;

    }

    .footer-links a:hover{

        color:#ffffff;

}

    /*==============================
            Responsive
    ==============================*/

@media(max-width:768px){

    .footer-top{

    grid-template-columns:1fr;

    text-align:center;

    }

    .footer-bottom{

    flex-direction:column;

    }

    .footer-links{

    justify-content:center;

    flex-wrap:wrap;

    }

    .footer-logo{

    margin:auto auto 20px;

    }

}

/* ===========================
   EXTRA RESPONSIVE
=========================== */

@media (max-width:768px){

    .course-grid,
    .playlist-grid,
    .testimonial-grid{
        grid-template-columns:1fr;
    }

    .course-footer{
        flex-direction:column;
        gap:20px;
        text-align:center;
    }

    .playlist-tabs{
        gap:10px;
    }

    .playlist-tabs button{
        width:100%;
    }

    .faq-item{
        padding:20px;
    }

    .footer h3{
        font-size:24px;
        
    }

}

.playlist-content{
    display:none;
}

.playlist-content.active{
    display:block;
}

.tab-btn{

    cursor:pointer;

}

.tab-btn.active{

    background:#0ea5e9;

    color:white;

}


/*==================================
        BACK TO TOP
==================================*/

.back-top{

    position:fixed;

    right:25px;

    bottom:25px;

    width:58px;

    height:58px;

    border:none;

    border-radius:50%;

    background:linear-gradient(135deg,#0ea5e9,#2563eb);

    color:#fff;

    font-size:22px;

    cursor:pointer;

    display:flex;

    justify-content:center;

    align-items:center;

    box-shadow:0 12px 35px rgba(14,165,233,.35);

    opacity:0;

    visibility:hidden;

    transform:translateY(20px);

    transition:.35s;

    z-index:999;

}

/* Show */

.back-top.show{

    opacity:1;

    visibility:visible;

    transform:translateY(0);

}

/* Hover */

.back-top:hover{

    transform:translateY(-6px) scale(1.08);

}

/* Rocket Animation */

.back-top i{

    transition:.35s;

}

.back-top:hover i{

    transform:rotate(-20deg);

}

/* Glow */

.back-top{

    animation:glow 2s infinite;

}

@keyframes glow{

    0%{

        box-shadow:0 0 10px rgba(14,165,233,.3);

    }

    50%{

        box-shadow:0 0 28px rgba(14,165,233,.7);

    }

    100%{

        box-shadow:0 0 10px rgba(14,165,233,.3);

    }

}

/*==================================
        APPLE THEME SWITCH
==================================*/

.theme-switch{

    display:flex;

    align-items:center;

    gap:12px;

}

.sun,
.moon{

    font-size:18px;

    color:#fbbf24;

}

.moon{

    color:#94a3b8;

}

.switch{

    position:relative;

    display:inline-block;

    width:58px;

    height:30px;

}

.switch input{

    display:none;

}

.slider{

    position:absolute;

    inset:0;

    background:#cbd5e1;

    border-radius:30px;

    cursor:pointer;

    transition:.35s;

}

.slider::before{

    content:"";

    position:absolute;

    width:24px;

    height:24px;

    left:3px;

    top:3px;

    background:#fff;

    border-radius:50%;

    transition:.35s;

    box-shadow:0 4px 12px rgba(0,0,0,.2);

}

.switch input:checked + .slider{

    background:#0ea5e9;

}

.switch input:checked + .slider::before{

    transform:translateX(28px);

}

/*==================================
        DARK MODE
==================================*/

body{

    transition:.35s;

}

body.dark{

    background:#0a1328;

    color:#f8fafc;

}

body.dark .header{

    background:#051a4b;

}

body.dark section{

    background:#051a4b;

}

body.dark h1,
body.dark h2,
body.dark h3,
body.dark h4{

    color:#fff;

}

body.dark p{

    color:#cbd5e1;

}

body.dark .course-card,
body.dark .video-card,
body.dark .testimonial-card,
body.dark .faq-item{

    background:#040e20;

    color:#fff;

}

body.dark .footer{

    background:#01030d;

}

body.dark .navbar a{

    color:#fff;

}