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

:root {
    --viewport-block: 100vh;
}

@supports (height: 100svh) {
    :root { --viewport-block: 100svh; }
}

@supports (height: 100lvh) {
    :root { --viewport-block: 100lvh; }
}

html,
body {
    scrollbar-width: none;
    -ms-overflow-style: none;
}

html::-webkit-scrollbar,
body::-webkit-scrollbar {
    width: 0;
    height: 0;
}

body {
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #ff6b9d 0%, #c06c84 25%, #6c5ce7 50%, #a29bfe 75%, #fd79a8 100%);
    background-size: 400% 400%;
    animation: gradient 15s ease infinite;
    position: relative;
    z-index: 0;
    min-height: var(--viewport-block);
    overflow-x: hidden;
}

body.bottom-focus-mode {
    background: #000;
    animation: none;
}

body.bottom-focus-mode::before {
    opacity: 0;
}

body.bottom-focus-mode .container {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

body.bottom-focus-mode .sidenav-cursor {
    z-index: 999;
}

body::before {
    content: '';
    position: fixed;
    left: 0;
    top: 0;
    right: 0;
    height: var(--viewport-block);
    background-image: url('img/kuromi-bg.jpg');
    background-repeat: no-repeat;
    background-position: center;
    background-size: contain;
    opacity: 0.6;
    pointer-events: none;
    z-index: -1;
}

.sidenav-cursor {
    --sidenav-size: 64px;
    position: fixed;
    right: calc(var(--sidenav-size) * -0.5);
    top: 12px;
    width: var(--sidenav-size);
    height: var(--sidenav-size);
    background-image: url('img/kuromi_sidenav.png');
    background-repeat: no-repeat;
    background-position: center;
    background-size: contain;
    pointer-events: none;
    z-index: 2;
    transform: translateY(0);
    transform-origin: center center;
    transition: transform 360ms cubic-bezier(0.2, 0.75, 0.2, 1),
                right 360ms cubic-bezier(0.2, 0.75, 0.2, 1),
                top 360ms cubic-bezier(0.2, 0.75, 0.2, 1),
                width 360ms cubic-bezier(0.2, 0.75, 0.2, 1),
                height 360ms cubic-bezier(0.2, 0.75, 0.2, 1);
    will-change: transform, right, top, width, height;
}

.sidenav-cursor.is-at-bottom {
    right: 50%;
    top: 50%;
    width: min(80vw, 80vh);
    height: min(80vw, 80vh);
    transform: translate3d(50%, -50%, 0);
}

.bottom-action-layer {
    position: fixed;
    inset: 0;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 260ms ease;
}

.bottom-action-layer.is-visible {
    opacity: 1;
}

.bottom-jump-btn {
    position: absolute;
    left: 50%;
    top: calc(50% - min(40vw, 40vh) - 28px);
    transform: translateX(-50%);
    pointer-events: auto;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 30px;
    border-radius: 999px;
    border: 2px solid rgba(255, 255, 255, 0.9);
    background: linear-gradient(135deg, #fff3f8 0%, #ffd7ea 100%);
    color: #53233d;
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-decoration: none;
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.28);
    transition: transform 220ms ease, box-shadow 220ms ease, background 220ms ease;
}

.bottom-jump-btn:hover {
    transform: translate(-50%, -4px);
    background: linear-gradient(135deg, #ffffff 0%, #ffe4f1 100%);
    box-shadow: 0 22px 44px rgba(0, 0, 0, 0.34);
}

.bottom-jump-btn:active {
    transform: translate(-50%, -1px);
}

.bottom-jump-btn:focus-visible {
    outline: 3px solid rgba(255, 255, 255, 0.95);
    outline-offset: 4px;
}

@keyframes gradient {
    0%   { background-position: 0% 50%; }
    50%  { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.container {
    position: relative;
    z-index: 1;
    width: 100%;
    min-height: calc(var(--viewport-block) * 2);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    color: white;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.hero {
    width: 100%;
    min-height: var(--viewport-block);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
}


.header {
    text-align: center;
    margin-bottom: 30px;
    animation: fadeIn 1s ease-in;
}

.title {
    font-size: 4rem;
    font-weight: bold;
    margin-bottom: 10px;
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50%       { transform: translateY(-20px); }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to   { opacity: 1; }
}


@media (prefers-reduced-motion: reduce) {
    .sidenav-cursor { transition: none; }
}

@media (max-width: 768px) {
    .title { font-size: 2.5rem; }

    .bottom-jump-btn {
        top: calc(50% - min(40vw, 34vh) - 22px);
        width: min(78vw, 320px);
        padding: 13px 24px;
        font-size: 0.95rem;
    }
}