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

:root {
    --primary-color: #007bff;
    --primary-light: #a1c4fd;
    --primary-dark: #0056b3;
    --secondary-color: #6c757d;
    --background-color: #e9ecef;
    --surface-color: #ffffff;
    --text-color: #343a40;
    --heading-font: 'Poppins', sans-serif;
    --body-font: 'Roboto', sans-serif;
    --accent-teal: #1abc9c;
    --accent-yellow: #f1c40f;
    --accent-green: #2ecc71;
    --accent-purple: #9b59b6;
    --shadow-color-light: rgba(0, 0, 0, 0.05);
    --shadow-color-dark: rgba(0, 0, 0, 0.1);
}

body {
    font-family: var(--body-font);
    background-color: var(--background-color);
    color: var(--text-color);
    background-image: url('data:image/svg+xml,%3Csvg width="6" height="6" viewBox="0 0 6 6" xmlns="http://www.w3.org/2000/svg"%3E%3Cg fill="%239C92AC" fill-opacity="0.1" fill-rule="evenodd"%3E%3Cpath d="M5 0h1L0 6V5zM6 5v1H5z"/%3E%3C/g%3E%3C/svg%3E');
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background-color: var(--surface-color);
    box-shadow: 0 4px 6px var(--shadow-color-light);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo a {
    font-family: var(--heading-font);
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links li {
    margin-left: 2.5rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 600;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: var(--primary-color);
}

.burger {
    display: none;
    cursor: pointer;
}

.burger div {
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    margin: 5px;
    transition: all 0.3s ease;
}

.hero {
    background-image: linear-gradient(rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.5)), url('https://images.unsplash.com/photo-1581009146145-b5ef050c2e1e?q=80&w=2070&auto=format&fit=crop&ixlib=rb-4.0.3&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D');
    background-size: cover;
    background-position: center;
    height: 90vh;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    color: var(--surface-color);
}

.hero-text h1 {
    font-family: var(--heading-font);
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.cta-btn {
    display: inline-block;
    padding: 1rem 2.5rem;
    background-color: var(--primary-color);
    color: var(--surface-color);
    text-decoration: none;
    border-radius: 50px;
    font-weight: 600;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 15px rgba(0, 123, 255, 0.4);
}

.cta-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0, 123, 255, 0.5);
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    padding: 5rem 2rem;
    background-color: var(--surface-color);
}

.feature {
    background: var(--surface-color);
    padding: 2.5rem;
    text-align: center;
    border-radius: 12px;
    box-shadow: 0 8px 25px var(--shadow-color-light);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 30px var(--shadow-color-dark);
}

.feature i {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
}

.feature:nth-child(1) i { color: var(--accent-teal); }
.feature:nth-child(2) i { color: var(--accent-yellow); }
.feature:nth-child(3) i { color: var(--primary-color); }
.feature:nth-child(4) i { color: var(--accent-purple); }

.feature h3 {
    font-family: var(--heading-font);
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

main {
    padding: 2rem;
}

.goal-selection, .deadline, #baseline-section, #plan-section, #calorie-calculator-section, .reviews, .community-posts, .photo-gallery, .contact, .health-apps-section, .generate-plan-section {
    padding: 3rem;
    margin-bottom: 2rem;
    border-radius: 12px;
    box-shadow: 0 8px 25px var(--shadow-color-light);
    background-color: var(--surface-color);
}

.generate-plan-section {
    text-align: center;
}

#plan-section {
    display: flex;
    gap: 2rem;
}

.plan-container {
    flex: 3;
}

.plan-week {
    margin-bottom: 2rem;
}

.plan-week h3 {
    font-family: var(--heading-font);
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary-dark);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 0.5rem;
    display: inline-block;
}

.plan-day-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.plan-day {
    background-color: #f8f9fa;
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px var(--shadow-color-light);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.plan-day:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px var(--shadow-color-dark);
}

.day-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    border-bottom: 1px solid #dee2e6;
    padding-bottom: 0.8rem;
}

.day-header h4 {
    font-size: 1.2rem;
    font-weight: 600;
}

.day-header input[type="checkbox"] {
    width: auto;
    margin: 0;
    transform: scale(1.3);
    cursor: pointer;
}

.plan-day p {
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 0.5rem;
}

.sponsored-ads {
    flex: 1;
    text-align: center;
}

.sponsored-ads h4 {
    font-family: var(--heading-font);
    font-size: 1rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.ads-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.ad {
    flex: 1;
}

.ad img {
    width: 100%;
    border-radius: 8px;
    margin-bottom: 0.5rem;
}

.ad p {
    font-size: 0.9rem;
    line-height: 1.4;
}

.goal-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.goal-card {
    background: var(--background-color);
    padding: 2rem;
    text-align: center;
    border-radius: 12px;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background-color 0.3s ease;
    border: 2px solid transparent;
}

.goal-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 30px var(--shadow-color-dark);
}

.goal-card.selected {
    background-color: var(--primary-color);
    color: var(--surface-color);
    border-color: var(--primary-dark);
    box-shadow: 0 8px 25px rgba(0, 123, 255, 0.4);
}

.goal-card.selected i, .goal-card.selected h4 {
    color: var(--surface-color);
}

.goal-card i {
    font-size: 3rem;
    margin-bottom: 1rem;
    transition: color 0.3s ease;
}

.goal-card h4 {
    font-family: var(--heading-font);
    font-size: 1.2rem;
    font-weight: 600;
    transition: color 0.3s ease;
}

.goal-card:nth-child(1) i { color: #e74c3c; }
.goal-card:nth-child(2) i { color: #3498db; }
.goal-card:nth-child(3) i { color: #9b59b6; }
.goal-card:nth-child(4) i { color: #f1c40f; }
.goal-card:nth-child(5) i { color: #1abc9c; }
.goal-card:nth-child(6) i { color: #2ecc71; }
.goal-card:nth-child(7) i { color: #e67e22; }
.goal-card:nth-child(8) i { color: #34495e; }

#feel-fit-baseline {
    display: flex;
    justify-content: space-evenly;
    gap: 2rem;
    align-items: flex-start;
}

.size-selector {
    flex: 1;
    max-width: 400px;
}

.size-selector h2 {
    font-.size: 1.5rem;
    text-align: center;
    margin-bottom: 1.5rem;
}

.slider-container {
    display: flex;
    align-items: center;
    gap: 1rem;
    width: 100%;
}

#current-size-label, #desired-size-label {
    font-family: var(--heading-font);
    font-weight: 600;
    font-size: 1.5rem;
    color: var(--primary-dark);
    padding: 0.5rem;
    border-radius: 8px;
    background-color: #e9ecef;
    min-width: 50px;
    text-align: center;
}

h2 {
    font-family: var(--heading-font);
    font-size: 2.2rem;
    margin-bottom: 1.5rem;
    text-align: center;
}

select, input[type="text"], input[type="date"], input[type="file"], button, textarea {
    width: 100%;
    padding: 1rem;
    border-radius: 8px;
    border: 1px solid #ced4da;
    margin-bottom: 1rem;
    font-size: 1rem;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 10px;
    border-radius: 5px;
    background: linear-gradient(90deg, var(--primary-light), var(--primary-color));
    outline: none;
    padding: 0;
    margin: 1rem 0;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    background: var(--surface-color);
    border: 3px solid var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    margin-top: -7px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transition: transform 0.2s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

input[type="range"]::-moz-range-thumb {
    width: 24px;
    height: 24px;
    background: var(--surface-color);
    border: 3px solid var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

button {
    background-color: var(--primary-color);
    color: var(--surface-color);
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.3s ease;
    border: none;
    border-radius: 50px;
    box-shadow: 0 4px 10px rgba(0, 123, 255, 0.3);
}

button:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
}

.hidden {
    display: none;
}

.review {
    background: var(--background-color);
    padding: 2rem;
    border-radius: 12px;
    margin-bottom: 1.5rem;
    box-shadow: 0 4px 15px var(--shadow-color-light);
    border-left: 5px solid var(--accent-teal);
}

.review span {
    font-style: italic;
    color: var(--secondary-color);
    font-weight: 500;
    display: block;
    margin-top: 1rem;
}

.gallery-images {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.gallery-images img {
    width: 100%;
    height: auto;
    border-radius: 8px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.gallery-images img:hover {
    transform: scale(1.05);
    box-shadow: 0 10px 20px var(--shadow-color-dark);
}

.health-apps-section {
    text-align: center;
}

.health-apps-logos {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin: 2.5rem 0;
}

.health-apps-logos i {
    font-size: 4.5rem;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.health-apps-logos i:hover {
    transform: translateY(-5px) scale(1.05);
}

.health-apps-logos .fa-strava {
    color: #fc4c02;
}

.health-apps-logos .fa-fitbit {
    color: #00B0B9;
}

.health-apps-logos .fa-shoe-prints {
    color: #7ED321;
}

.health-apps-logos .fa-utensils {
    color: #F5A623;
}


@media screen and (max-width: 768px) {
    .nav-links {
        position: absolute;
        right: 0px;
        height: 92vh;
        top: 8vh;
        background-color: var(--surface-color);
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        width: 50%;
        transform: translateX(100%);
        transition: transform 0.5s ease-in;
    }

    .nav-links.nav-active {
        transform: translateX(0%);
    }
    
    .burger {
        display: block;
    }

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

    .goal-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    }

    .size-selector {
        width: 100%;
        margin-bottom: 2rem;
    }

    #plan-section {
        flex-direction: column;
    }

    .ads-container {
        flex-direction: row;
    }
}