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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Poppins', sans-serif;
    color: #fff; 
}

header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: #a8daf5;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 5rem;
    height: 100px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    z-index: 999;
}

.logo img {
    height: 100px;
    width: auto;
    border-radius: 50%;
    object-fit: cover;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 2rem;
    margin: 0;
    padding: 0;
}
nav ul li a {
    text-decoration: none;
    color: #003366;         
    font-weight: 600;
    border-radius: 4px;
    transition: color 0.3s ease, text-decoration-color 0.3s ease;
    text-underline-offset: 4px;   
}

nav ul li a:hover {
    color: #0077cc;            
    text-decoration: underline;
    text-decoration-color: #0077cc; 
}
nav ul li a.active {
    color: #0077cc;
    font-weight: 700;
    text-decoration: underline;
    text-underline-offset: 4px;
}

.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    background-image: url('bg-image.jpg'); 
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
    padding-top: 80px;
    line-height: 4px;
}

.hero h1 {
    font-size: 4rem;
    font-weight: 900;
    color: #0b0b0b;
    margin-bottom: 2rem;
}

.hero h2 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: #080808;
}

.hero p {
    color: #080808;
    font-size: 1.2rem;
    font-weight: 400;
    max-width: 700px;
    line-height: 2rem;
    margin-bottom: 2rem;
}

.btn {
    display: inline-block;
    padding: 0.8rem ;
    background-color: #69c0ff;
    color: #0c0c0c;
    border-radius: 30px;
    font-weight: 600;
    text-decoration: none;
    transition: background-color 0.3s, transform 0.3s;
}

.btn:hover {
    background-color: #005fa3;
    transform: scale(1.05);
}
html, body {
    height: 100%;
    margin: 0;
    display: flex;
    flex-direction: column;
}

.wrapper {
    flex: 1; 
}

.site-footer {
    background-color: #003366;
    color: #ffffff;
    padding: 1rem 0;
    text-align: center;
    font-size: 0.95rem;
}

.image-container {
    display: inline-block;
    max-width: 100%;
    height: auto;
}
img {
    max-width: 1000px;
    height: 400px;
}

section {
    scroll-margin-top: 80px;
}

.info-section {
    padding: 4rem 2rem;
    background-color: #f9f9f9;
}

.info-section h2 {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 2rem;
    color: #1a1a1a;
}

.info-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.card {
    background-color: #fefefe;
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #222;
}

.card p {
    font-size: 1rem;
    color: #555;
    line-height: 1.6;
}
.altitude-chart {
    flex:1;
    min-width: 300px;
    max-width: 500px;
    padding: 20px;
    background-color: #e4eff8; 
}
.altitude-layout {
    display: flex;
    justify-content: space-between;
    align-items: flex-start; 
    gap: 10px;             
    flex-wrap: wrap;       
    padding: 20px;
}
.chart-head{
    text-align: center;
    margin-top: 2rem;
    margin-bottom: 2rem;
}
table{
    color: black;
    font-size: 1.2rem; 
    width: 100%;
    border-collapse: collapse;
    text-align: center;
}
.altitude-chart h2 {
    margin-bottom: 1rem;
    text-align: center;
    font-size: 2rem;
    color: #003366;
}

.altitude-chart table {
    border-collapse: collapse;
    width: 100%;
    max-width: 500px;
}

.altitude-chart th, .altitude-chart td {
    padding: 0.75rem 1rem;
    text-align: center;
    border-bottom: 1px solid #ccc;
}

.altitude-chart th {
    background-color: #eeeeee;
}

.altitude-chart a {
    display: inline-block;
    margin-top: 0.5rem;
    color: #4a00e0;
    text-decoration: none;
}

.altitude-chart a:hover {
    text-decoration: underline;
}

.about-section {
    padding: 6rem 2rem;
    background-color: #fdfdfd;
    color: #333;
}

.about-section .container {
    max-width: 900px;
    margin: 0 auto;
}

.about-section h2 {
    text-align: center;
    font-size: 2.5rem;
    color: #1a1a1a;
    margin-bottom: 2rem;
}

.about-section h3 {
    margin-top: 2rem;
    font-size: 1.75rem;
    color: #222;
}

.about-section p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-top: 1rem;
}

.about-section ul {
    margin-top: 1rem;
    padding-left: 1.5rem;
}

.about-section ul li {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}
.graph{
    max-width: 750px;
    min-height:400px;
    margin: 2rem auto;
    background: white;
    border-radius: 12px;
    padding: 6rem 5rem;
    
    text-align: center;

}
.graph h1{
    color:#003060;
    font-size:2rem;
}
.graph p{
    margin-top: 50px;
    color:#003060
}
label {
    font-size: 1.2rem;
    font-weight: 600;
}
input[type="range"] {
    width: 80%;
    margin: 1rem;
}
.boiling-temp {
    font-size: 2.2rem;
    font-weight: 700;
    margin-top: 0.5rem;
    color: #0d47a1;
}
canvas {
    margin-top: 1rem;
    max-width: 600px;
    border-radius: 12px;
    height: 350px;
    box-shadow: 0 6px 20px rgba(0,0,0,0.1);
}
.calculator 
{
    max-width: 500px;
    min-height: 300px;
    margin: 10rem auto;
    padding: 5rem;
    background-color: #fff;
    box-shadow: 0 4px 12px rgba(255, 250, 250, 0.914);
    border-radius: 10px;
}
.calculator h2 {
    margin-bottom: 1.5rem;
    text-align: center;
    color: #004080;
}

.calculator label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: bold;
}

.calculator input {
    width: 100%;
    padding: 0.5rem;
    margin-bottom: 1.2rem;
    border: 1px solid #ccc;
    border-radius: 5px;
}

.calculator button {
    width: 100%;
    padding: 0.7rem;
    background-color: #004080;
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
}

.calculator button:hover {
    background-color: #003060;
}

.result {
    margin-top: 1.5rem;
    text-align: center;
    font-size: 1.2rem;
    font-weight: bold;
    color: #007700;
}
.mountain-container 
{
    position: relative;
    width: 500px;
    height: 600px;
    margin: 60px auto;
    padding: 6rem;
    background-image: url('mountain2.png');
    background-size: cover;
    background-position: center;
    border: 2px solid #444;
    cursor: crosshair;
}
#hoverAltitude {
    position: absolute;
    top: 10px;
    left: 10px;
    background: rgb(173, 152, 152);
    color: #fff;
    padding: 5px 8px;
    border-radius: 5px;
    font-size: 0.9rem;
}
#clickMarker {
    position: absolute;
    width: 12px;
    height: 12px;
    background: red;
    border-radius: 50%;
    pointer-events: none;
    transform: translate(-50%, -50%);
    display: none;
}
#output {
    margin-top: 20px;
    font-size: 1.2rem;
    color: #313030;
    text-align: center;
}
main 
{
    max-width: 700px;
    min-height: 600px;
    margin: 2rem auto;
    background: white;
    border-radius: 12px;
    padding: 10rem 3rem;
    box-shadow: 0 6px 18px rgba(0,0,0,0.15);
    text-align: center;
}
.question {
    font-size: 1.4rem;
    font-weight: 700;
    color: #080808;
    padding-bottom: 3rem;
}
.options {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 1.5rem;
}
button.option-btn {
    background-color: #1e88e5;
    color: white;
    border: none;
    padding: 0.9rem 1.5rem;
    font-size: 1.1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}
button.option-btn:hover:not(:disabled) {
    background-color: #1565c0;
}
button.option-btn:disabled {
    background-color: #90a4ae;
    cursor: not-allowed;
}
#nextBtn {
    background-color: #219653;
    margin-top: 0.5rem;
    padding: 0.9rem 2rem;
    font-weight: 700;
    font-size: 1.1rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}
#nextBtn:hover:not(:disabled) {
    background-color: #1b7a3b;
}
#nextBtn:disabled {
    background-color: #90a4ae;
    cursor: not-allowed;
}
.feedback {
    font-size: 1.2rem;
    font-weight: 700;
    margin-top: 1rem;
}
#score {
    font-size: 1.5rem;
    font-weight: 800;
    color: #0d47a1;
    margin: 1rem 0;
}
#grade {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: #d45200;
}