/* ================= GLOBAL ================= */

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

body{
    font-family:'Poppins',sans-serif;
    background:#f5f7ff;
    overflow-x:hidden;
}

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

.top-header{
    width:100%;
    padding:18px 60px;
    display:flex;
    justify-content:space-between;
    align-items:center;

    background:
    linear-gradient(
        135deg,
        #4568dc,
        #6a5acd
    );
}

.left-logo img,
.right-logo img{
    width:90px;
    height:90px;
    object-fit:contain;

    background:white;

    padding:8px;

    border-radius:15px;
}

.header-text{
    text-align:center;
    color:white;
}

.header-text h1{
    font-size:36px;
    font-weight:700;
}

.iit-link{
    display:inline-block;
    margin-top:10px;

    color:#f3f3f3;

    text-decoration:none;

    font-size:17px;
}

.iit-link:hover{
    color:#ffe082;
}

/* ================= NAVBAR ================= */

.navbar{
    background:white;

    display:flex;
    justify-content:center;
    align-items:center;

    gap:40px;

    padding:18px;

    box-shadow:0 2px 10px rgba(0,0,0,0.08);

    position:sticky;
    top:0;
    z-index:1000;
}

.navbar a{
    text-decoration:none;

    color:#222;

    font-size:17px;
    font-weight:500;

    position:relative;

    transition:0.3s;
}

.navbar a:hover,
.navbar .active{
    color:#4568dc;
}

/* UNDERLINE */

.navbar a::after{
    content:"";

    position:absolute;

    width:0%;
    height:2px;

    background:#4568dc;

    left:0;
    bottom:-5px;

    transition:0.4s;
}

.navbar a:hover::after{
    width:100%;
}

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

.hero-section{
    position:relative;

    height:90vh;

    background:
    url("images/slide2.jpg")
    center/cover no-repeat;

    display:flex;
    justify-content:center;
    align-items:center;
}

/* OVERLAY */

.overlay{
    position:absolute;
    inset:0;

    background:
    rgba(0,0,0,0.65);
}

/* CONTENT */

.hero-content{
    position:relative;
    z-index:2;

    text-align:center;

    color:white;

    max-width:900px;

    padding:20px;
}

.hero-content h1{
    font-size:70px;
    margin-bottom:20px;
}

.hero-content p{
    font-size:22px;
    line-height:1.8;
    margin-bottom:35px;
}

/* BUTTON */

.hero-btn{
    display:inline-block;

    text-decoration:none;

    background:white;

    color:#4568dc;

    padding:16px 38px;

    border-radius:40px;

    font-weight:600;

    transition:0.4s;
}

.hero-btn:hover{
    background:#4568dc;
    color:white;

    transform:translateY(-5px);
}

/* ================= SECTION TITLE ================= */

.section-title{
    text-align:center;
    margin-bottom:60px;
}

.section-title h2{
    font-size:50px;
    color:#222;
    margin-bottom:15px;
}

.section-title p{
    color:#666;
    font-size:18px;
}

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

.about-section{
    padding:90px 70px;
}

.research-cards{
    display:grid;

    grid-template-columns:
    repeat(auto-fit,minmax(280px,1fr));

    gap:35px;
}

/* CARD */

.research-card{
    background:white;

    padding:40px 30px;

    border-radius:25px;

    text-align:center;

    transition:0.4s;

    box-shadow:
    0 10px 25px rgba(0,0,0,0.08);
}

.research-card:hover{
    transform:translateY(-12px);

    background:
    linear-gradient(
        135deg,
        #4568dc,
        #6a5acd
    );

    color:white;
}

.icon{
    font-size:55px;
    margin-bottom:20px;
}

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

.research-card p{
    line-height:1.8;
}

/* ================= SAMPLE SECTION ================= */

.sample-section{
    padding:90px 70px;

    background:#eef3ff;
}

.sample-gallery{
    display:grid;

    grid-template-columns:
    repeat(auto-fit,minmax(320px,1fr));

    gap:35px;
}

/* SAMPLE BOX */

.sample-box{
    background:white;

    border-radius:25px;

    overflow:hidden;

    transition:0.4s;

    box-shadow:
    0 10px 25px rgba(0,0,0,0.08);
}

.sample-box:hover{
    transform:translateY(-10px);
}

/* IMAGE */

.sample-box img{
    width:100%;
    height:260px;
    object-fit:cover;

    transition:0.5s;
}

.sample-box:hover img{
    transform:scale(1.05);
}

/* TEXT */

.sample-text{
    padding:25px;
}

.sample-text h3{
    font-size:28px;
    margin-bottom:10px;
    color:#222;
}

.sample-text p{
    color:#666;
    line-height:1.7;
}

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

.footer{
    background:#222;
    color:white;

    text-align:center;

    padding:22px;

    font-size:16px;
}

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

@media(max-width:768px){

    .top-header{
        flex-direction:column;
        gap:20px;
        padding:20px;
    }

    .header-text h1{
        font-size:26px;
    }

    .navbar{
        flex-wrap:wrap;
        gap:20px;
    }

    .hero-content h1{
        font-size:42px;
    }

    .hero-content p{
        font-size:18px;
    }

    .about-section,
    .sample-section{
        padding:60px 20px;
    }

    .section-title h2{
        font-size:36px;
    }
}