:root {
    --primary-color: #FF6B9D;
    --primary-hover: #F9508A;

    --bg-color: #ffffff;
    --bg-secondary: #f7f9f9;

    --text-color: #0f1419;
    --sub-text: #536471;

    --border-color: #eff3f4;
    --hover-color: #f2f3f4;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #000000;
        --bg-secondary: #16181c;

        --text-color: #e7e9ea;
        --sub-text: #71767b;

        --border-color: #2f3336;
        --hover-color: #181818;
    }
}

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

body {
    background: var(--bg-color);
    color: var(--text-color);

    font-family:
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        Roboto,
        Helvetica,
        Arial,
        sans-serif;
}

.app {
    max-width: 720px;
    margin: 0 auto;
    min-height: 100vh;
    border-left: 1px solid var(--border-color);
    border-right: 1px solid var(--border-color);
}

/* =========================
   TOP BAR
========================= */

.topbar {
    position: sticky;
    top: 0;

    z-index: 100;

    background: rgba(255,255,255,0.85);
    backdrop-filter: blur(12px);

    border-bottom: 1px solid var(--border-color);

    padding: 12px 16px;

    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

@media (prefers-color-scheme: dark) {
    .topbar {
        background: rgba(0,0,0,0.85);
    }
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;

    min-width: 0;
}

.brand-text {
    min-width: 0;
}

.brand-text h1 {
    font-size: 1rem;
    font-weight: 800;

    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.brand-text p {
    font-size: 0.82rem;
    color: var(--sub-text);

    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* =========================
   CATEGORY BAR
========================= */

.category-bar {
    position: sticky;
    top: 67px;

    z-index: 90;

    display: flex;
    gap: 8px;

    overflow-x: auto;

    padding: 12px 16px;

    background: var(--bg-color);

    border-bottom: 1px solid var(--border-color);

    scrollbar-width: none;
}

.category-bar::-webkit-scrollbar {
    display: none;
}

.nav-item {
    flex-shrink: 0;

    display: flex;
    align-items: center;
    gap: 6px;

    padding: 8px 14px;

    border-radius: 9999px;

    background: var(--bg-secondary);

    font-size: 0.95rem;
    font-weight: 700;

    cursor: pointer;

    transition: background 0.2s, opacity 0.2s;
}

.nav-item:hover {
    background: var(--hover-color);
}

.nav-item.active {
    background: var(--primary-color);
    color: white;
}

/* 件数0のカテゴリ */
.nav-item--empty {
    opacity: 0.45;
    cursor: default;
    pointer-events: none;
}

/* =========================
   ナビ 件数バッジ
========================= */

.nav-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;

    min-width: 20px;
    height: 20px;
    padding: 0 5px;

    border-radius: 9999px;

    font-size: 0.72rem;
    font-weight: 700;
    line-height: 1;

    background: rgba(0,0,0,0.10);
    color: inherit;

    transition: background 0.2s;
}

.nav-item.active .nav-badge {
    background: rgba(255,255,255,0.30);
    color: white;
}

@media (prefers-color-scheme: dark) {
    .nav-badge {
        background: rgba(255,255,255,0.12);
    }
}

/* =========================
   CONTROLS
========================= */

.controls select {
    border: 1px solid var(--border-color);

    background: var(--bg-color);
    color: var(--text-color);

    border-radius: 9999px;

    padding: 8px 14px;

    font-size: 0.9rem;
    
    cursor: pointer;
}

/* =========================
   TWEETS
========================= */

.tweets-grid {
    display: flex;
    flex-direction: column;

    transition: opacity 0.15s ease;
}

/* カテゴリ切替時のフェードアウト */
.tweets-grid--fade-out {
    opacity: 0;
}

.tweet-card {
    padding: 12px;

    border-bottom: 1px solid var(--border-color);

    display: flex;
    justify-content: center;

    position: relative;
    touch-action: pan-y;
}

/* =========================
   iOS Safari / Android iframe スクロール対策
   スクロール中は iframe の pointer-events を無効化し、
   タッチを親ページに素通りさせる。
========================= */

body.is-scrolling .tweet-card iframe {
    pointer-events: none !important;
}

/* =========================
   スケルトンローディング
========================= */

@keyframes skeleton-shimmer {
    0%   { background-position: -400px 0; }
    100% { background-position:  400px 0; }
}

.tweet-skeleton {
    width: 100%;
    max-width: 550px;
    padding: 16px 0 8px;
}

.tweet-skeleton__header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 12px;
}

.tweet-skeleton__avatar {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    flex-shrink: 0;
    background: var(--skeleton-base, #e8ebed);
    background-image: linear-gradient(
        90deg,
        var(--skeleton-base, #e8ebed) 0px,
        var(--skeleton-shine, #f4f5f6) 80px,
        var(--skeleton-base, #e8ebed) 160px
    );
    background-size: 400px 100%;
    animation: skeleton-shimmer 1.4s infinite linear;
}

.tweet-skeleton__meta {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.tweet-skeleton__line {
    height: 12px;
    border-radius: 6px;
    background: var(--skeleton-base, #e8ebed);
    background-image: linear-gradient(
        90deg,
        var(--skeleton-base, #e8ebed) 0px,
        var(--skeleton-shine, #f4f5f6) 80px,
        var(--skeleton-base, #e8ebed) 160px
    );
    background-size: 400px 100%;
    animation: skeleton-shimmer 1.4s infinite linear;
}

.tweet-skeleton__line--name   { width: 40%; animation-delay: 0.05s; }
.tweet-skeleton__line--handle { width: 28%; height: 10px; animation-delay: 0.1s; }
.tweet-skeleton__line--text   { width: 90%; margin-top: 8px; animation-delay: 0.05s; }
.tweet-skeleton__line--short  { width: 65%; animation-delay: 0.1s; }

@media (prefers-color-scheme: dark) {
    .tweet-skeleton__avatar,
    .tweet-skeleton__line {
        --skeleton-base:  #2a2d31;
        --skeleton-shine: #3a3d42;
    }
}

/* =========================
   エラー・空状態
========================= */

.tweet-error,
.tweet-empty {
    padding: 20px;
    font-size: 0.875rem;
    color: var(--sub-text);
    text-align: center;
}

.tweet-error {
    color: var(--primary-color);
}

/* =========================
   LOAD MORE / SENTINEL
========================= */

.load-more-container {
    padding: 24px;
    text-align: center;
}

#scroll-sentinel {
    height: 1px;
    visibility: hidden;
}

.btn-primary {
    border: none;

    background: var(--primary-color);
    color: white;

    border-radius: 9999px;

    padding: 12px 20px;

    font-weight: 700;

    cursor: pointer;

    transition: 0.2s;
}

.btn-primary:hover {
    background: var(--primary-hover);
}

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

@media (max-width: 768px) {

    .app {
        border-left: none;
        border-right: none;
    }

    .topbar {
        padding: 10px 12px;
    }

    .brand-text h1 {
        font-size: 0.95rem;
    }

    .brand-text p {
        font-size: 0.75rem;
    }

    .controls select {
        font-size: 0.8rem;
        padding: 7px 12px;
    }

    .category-bar {
        top: 63px;
        padding: 10px 12px;
    }

    .nav-item {
        font-size: 0.85rem;
        padding: 8px 12px;
        gap: 5px;
    }

    .nav-badge {
        font-size: 0.68rem;
        min-width: 18px;
        height: 18px;
    }

    .tweet-card {
        padding: 8px;
    }
}

/* =========================
   HEADER RIGHT
========================= */

.header-right {
    display: flex;
    align-items: center;
    gap: 14px;
}

.sns-links {
    display: flex;
    align-items: center;
    gap: 8px;
}

.sns-icon-link {
    width: 36px;
    height: 36px;

    border-radius: 9999px;

    display: flex;
    align-items: center;
    justify-content: center;

    text-decoration: none;

    background: var(--bg-secondary);

    color: var(--text-color);

    font-weight: 700;
    font-size: 0.95rem;

    transition:
        transform 0.15s ease,
        background 0.2s ease;
}

.sns-icon-link:hover {
    background: var(--hover-color);

    transform: translateY(-1px);
}

/* =========================
   SEO DESCRIPTION
========================= */

.seo-description {
    padding: 40px 24px 80px;

    color: var(--sub-text);

    line-height: 1.9;

    font-size: 0.95rem;
}

.seo-description h2 {
    color: var(--text-color);

    font-size: 1.1rem;

    margin-bottom: 16px;
}

.seo-description p {
    margin-bottom: 16px;
}