/* --- VARIABLES & BASIC SETUP --- */
:root {
    --main-color: #e6762b;
    --sub-color: #5fae1d;
    --accent-color: #F5C959;
    --bg-color-start: #c0e95d; /* Lighter shade of user's choice */
    --bg-color-end: #5fae1d;   /* User's choice */
    --text-color: #333;
    --card-bg: #ffffff;
    --white: #fff;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans JP', sans-serif;
    background-image: linear-gradient(170deg, var(--bg-color-start) 0%, var(--bg-color-end) 100%);
    color: var(--text-color);
    margin: 0;
    padding: 40px 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    box-sizing: border-box;
    position: relative; /* For z-index stacking context */
}

#particle-canvas {
    position: fixed; /* Changed from absolute to fixed for better viewport coverage */
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1; /* Ensure it's behind all other content */
    pointer-events: none; /* Make sure it doesn't interfere with mouse events */
}

/* --- ANIMATIONS --- */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* --- MAIN LAYOUT --- */
.container {
    max-width: 680px;
    width: 100%;
    text-align: center;
    animation: fadeIn 0.8s ease-out forwards;
    position: relative; /* Ensure container is above the canvas */
    z-index: 1;
}

/* --- HEADER SECTION --- */
header {
    background-color: var(--card-bg);
    padding: 40px;
    border-radius: 16px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05), 0 10px 30px rgba(40, 50, 70, 0.08);
    margin-bottom: 50px;
}

.logo {
    max-width: 120px;
    margin-bottom: 25px;
    transition: transform 0.3s ease;
}
.logo:hover {
    transform: scale(1.05);
}

h1 {
    font-size: 1.8rem; /* Slightly smaller for a more refined look */
    font-weight: 700;
    margin: 0 0 15px 0;
    letter-spacing: 0.05em;
    line-height: 1.5;
}

.intro {
    font-size: 1rem;
    color: #555;
    max-width: 480px;
    margin: 0 auto;
    line-height: 1.7;
}

/* --- LINKS SECTION --- */
.links-container {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.link-button {
    display: flex;
    align-items: center;
    padding: 15px 25px;
    background-color: var(--card-bg);
    border-radius: 12px;
    text-decoration: none;
    color: var(--text-color);
    font-size: 1.1rem;
    font-weight: 600;
    transition: transform 0.25s ease, box-shadow 0.25s ease, background-color 0.25s ease, color 0.25s ease;
    box-shadow: 0 2px 5px rgba(0,0,0,0.06);
    position: relative;
    overflow: hidden;
}

.link-button:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 15px rgba(40, 50, 70, 0.1);
    background-color: var(--main-color);
    color: var(--white);
}



.link-icon {
    width: 40px;
    height: 40px;
    margin-right: 20px;
    border-radius: 0px;
    object-fit: cover;
}

.link-button span {
    flex-grow: 1;
    text-align: left;
}

/* YouTube Icon Hover Effect */
#youtube-link .hover-youtube-icon {
    display: none;
}

#youtube-link:hover .default-youtube-icon {
    display: none;
}

#youtube-link:hover .hover-youtube-icon {
    display: inline-block; /* Or 'block' if it suits layout better, ensure it matches .link-icon display */
}

/* --- FOOTER --- */
footer {
    margin-top: 30px;
    padding: 10px 20px;
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.8);
    text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* スローガン（.tagline）に、H1と同じスタイルを適用 */
.tagline {
    font-size: 1.8rem; /* H1と同じサイズ */
    font-weight: 700;  /* H1と同じ太さ */
    margin: 0 0 20px 0;
    letter-spacing: 0.05em;
    line-height: 1.5;
    color: var(--main-color);
}

/* --- RESPONSIVE DESIGN --- */
@media (max-width: 768px) {
    body {
        padding: 20px 15px;
        align-items: flex-start; /* Allow scrolling on mobile */
    }

    header {
        padding: 30px 25px;
        margin-bottom: 40px;
    }

    h1 {
        font-size: 1.5rem;
        letter-spacing: normal;
    }

    .intro {
        font-size: 0.9rem;
    }

    .link-button {
        padding: 15px;
        font-size: 1rem;
    }

    .link-icon {
        width: 35px;
        height: 35px;
        margin-right: 15px;
    }
}