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

html {
    scroll-behavior: smooth;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    background: #f5f8fc;
    color: #172033;
}


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

.navbar {
    height: 72px;
    padding: 0 8%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: white;
    border-bottom: 1px solid #e5eaf1;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 28px;
    font-weight: 800;
    color: #172033;
}

.logo span {
    color: #2878f0;
}

.navbar nav {
    display: flex;
    gap: 35px;
}

.navbar nav a {
    text-decoration: none;
    color: #536174;
    font-weight: 600;
    transition: 0.3s;
}

.navbar nav a:hover {
    color: #2878f0;
}


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

.hero {
    min-height: 600px;
    display: flex;
    align-items: center;
    padding: 80px 8%;
    background: linear-gradient(
        135deg,
        #eef6ff,
        #ffffff
    );
}

.hero-content {
    max-width: 750px;
}

.tag {
    color: #2878f0;
    font-size: 14px;
    font-weight: 800;
    letter-spacing: 2px;
    margin-bottom: 20px;
}

.hero h1 {
    font-size: 58px;
    line-height: 1.1;
    margin-bottom: 25px;
}

.hero h1 span {
    color: #2878f0;
}

.description {
    max-width: 650px;
    font-size: 18px;
    line-height: 1.7;
    color: #647184;
    margin-bottom: 35px;
}

.start-btn {
    display: inline-block;
    padding: 15px 30px;
    background: #2878f0;
    color: white;
    text-decoration: none;
    border-radius: 10px;
    font-weight: 700;
    box-shadow: 0 8px 20px rgba(40, 120, 240, 0.25);
    transition: 0.3s;
}

.start-btn:hover {
    transform: translateY(-3px);
}


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

.screening {
    padding: 90px 8%;
    background: white;
}

.section-title {
    text-align: center;
    margin-bottom: 50px;
}

.section-title p {
    color: #2878f0;
    font-size: 13px;
    font-weight: 800;
    letter-spacing: 2px;
    margin-bottom: 12px;
}

.section-title h2 {
    font-size: 38px;
    margin-bottom: 12px;
}

.section-title span {
    color: #718096;
}


/* ================= UPLOAD ================= */

.upload-card {
    max-width: 650px;
    margin: auto;
    padding: 55px 30px;
    text-align: center;
    border: 2px dashed #cbd8e8;
    border-radius: 20px;
    background: #f8fbff;
}

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

.upload-card h3 {
    font-size: 24px;
    margin-bottom: 10px;
}

.upload-card p {
    color: #718096;
    margin-bottom: 25px;
}

.upload-btn {
    border: none;
    background: #2878f0;
    color: white;
    padding: 13px 25px;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 700;
    cursor: pointer;
    transition: 0.3s;
}

.upload-btn:hover {
    background: #1765d1;
}

#fileName {
    margin-top: 18px;
    color: #2878f0;
    font-weight: 600;
}


/* ================= PREVIEW ================= */

.preview-section {
    display: none;
    max-width: 900px;
    margin: 50px auto;
    text-align: center;
}

.image-box {
    background: #f8fafc;
    padding: 25px;
    border-radius: 15px;
    margin-bottom: 25px;
}

.image-box h3 {
    margin-bottom: 20px;
}

#previewImage {
    max-width: 100%;
    max-height: 450px;
    border-radius: 12px;
    object-fit: contain;
}

.analyze-btn {
    padding: 15px 35px;
    border: none;
    border-radius: 9px;
    background: #172033;
    color: white;
    font-size: 16px;
    font-weight: 700;
    cursor: pointer;
    transition: 0.3s;
}

.analyze-btn:hover {
    background: #2878f0;
}


/* ================= RESULTS ================= */

.result-section {
    display: none;
    max-width: 1000px;
    margin: 60px auto 0;
}

.result-section > h2 {
    text-align: center;
    margin-bottom: 30px;
    font-size: 32px;
}

.result-card {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 40px;
}

.result-item {
    background: #f8fbff;
    border: 1px solid #e1e8f0;
    border-radius: 15px;
    padding: 25px;
    text-align: center;
}

.result-item span {
    display: block;
    color: #718096;
    margin-bottom: 12px;
}

.result-item strong {
    font-size: 25px;
    color: #2878f0;
}


/* ================= GRAD-CAM ================= */

.explanation {
    text-align: center;
    background: #f8fbff;
    padding: 35px;
    border-radius: 18px;
}

.explanation h3 {
    font-size: 25px;
    margin-bottom: 12px;
}

.explanation p {
    color: #718096;
    margin-bottom: 25px;
}

#gradcamImage {
    max-width: 100%;
    border-radius: 12px;
}


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

.about {
    padding: 90px 8%;
    background: #f5f8fc;
}

.features {
    max-width: 1100px;
    margin: auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
}

.feature-card {
    background: white;
    padding: 35px;
    border-radius: 15px;
    border: 1px solid #e5eaf1;
    transition: 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 30px rgba(20, 40, 80, 0.08);
}

.feature-card h3 {
    margin-bottom: 15px;
    color: #2878f0;
}

.feature-card p {
    color: #667085;
    line-height: 1.6;
}


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

footer {
    text-align: center;
    padding: 35px;
    background: #172033;
    color: white;
}

footer p {
    font-weight: 700;
    margin-bottom: 8px;
}

footer small {
    color: #aeb8c7;
}


/* ================= MOBILE ================= */

@media (max-width: 768px) {

    .navbar {
        padding: 0 5%;
    }

    .navbar nav {
        gap: 15px;
    }

    .hero {
        padding: 70px 5%;
    }

    .hero h1 {
        font-size: 40px;
    }

    .screening,
    .about {
        padding: 70px 5%;
    }

    .section-title h2 {
        font-size: 30px;
    }

    .result-card {
        grid-template-columns: 1fr;
    }

    .features {
        grid-template-columns: 1fr;
    }
}