/* Gomoku — dark neon theme */
:root {
    --bg: #0d1321;
    --bg2: #121c30;
    --card: #1a2235;
    --border: #1e2a45;
    --cyan: #4fc3f7;
    --purple: #ab47bc;
    --gold: #ffd700;
    --text: #e6e9ef;
    --text-dim: #8892a8;
    --danger: #ff6b6b;
    --success: #4cd137;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: -apple-system, "Segoe UI", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
    background: linear-gradient(135deg, #0d1321 0%, #1a1f3a 100%);
    color: var(--text);
    min-height: 100vh;
}

/* 导航 */
.navbar {
    background: linear-gradient(135deg, #0d1321 0%, #1a1f3a 100%);
    border-bottom: 1px solid var(--border);
    padding: 0.8rem 0;
}
.nav-inner {
    max-width: 1200px; margin: 0 auto; display: flex;
    align-items: center; justify-content: space-between; padding: 0 2rem;
}
.nav-brand {
    font-size: 1.3rem; font-weight: 700;
    background: linear-gradient(135deg, #4fc3f7, #ab47bc);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.nav-links-box { display: flex; align-items: center; gap: 1.5rem; }
.nav-links-box a { color: var(--text-dim); font-weight: 500; font-size: .95rem; text-decoration: none; }
.nav-links-box a:hover { color: var(--cyan); }
#lang-toggle {
    background: none; border: 1px solid var(--cyan); color: var(--cyan);
    padding: 4px 12px; border-radius: 6px; cursor: pointer; font-size: .85rem;
}
#lang-menu {
    display: none; position: fixed; top: 70px; right: 20px; background: #141d2e;
    border: 1px solid var(--border); border-radius: 10px; padding: 8px 0; z-index: 200;
    box-shadow: 0 4px 20px rgba(0,0,0,.5);
}
#lang-menu a { display: block; padding: 8px 20px; color: var(--text-dim); text-decoration: none; font-size: .9rem; }
#lang-menu a:hover { color: var(--cyan); background: rgba(79,195,247,.1); }

/* 游戏区 */
#game-area {
    display: flex; justify-content: center; padding: 1.5rem 1rem;
}
#game-container {
    width: 100%; max-width: 560px;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 1rem;
    box-shadow: 0 8px 30px rgba(0,0,0,.45);
}
#canvas-wrapper { position: relative; }
#boardCanvas { width: 100%; display: block; border-radius: 10px; background: #e8d4a8; cursor: pointer; touch-action: manipulation; }

/* HUD */
#hud {
    display: flex; align-items: center; justify-content: space-between;
    padding: 0.5rem 0.25rem 0.75rem;
}
#turn-display { font-size: 1.05rem; font-weight: 600; color: var(--text); }
#winner-banner {
    font-size: 1.3rem; font-weight: 700; color: var(--gold);
    padding: .25rem .75rem; border-radius: 8px; background: rgba(255,215,0,.12);
}
.hidden { display: none !important; }

/* 菜单条 */
#menu-bar { display: flex; flex-wrap: wrap; gap: .75rem; align-items: center; padding: .6rem 0; }
.menu-group { display: flex; align-items: center; gap: .4rem; background: var(--bg2); border: 1px solid var(--border); border-radius: 10px; padding: .35rem; }
.menu-label { font-size: .8rem; color: var(--text-dim); padding: 0 .2rem; }
.spinner-label:after { content: ' ▾'; }
.chip {
    background: transparent; color: var(--text-dim); border: 1px solid var(--border);
    padding: .35rem .75rem; border-radius: 8px; cursor: pointer; font-size: .85rem; transition: all .15s;
}
.chip:hover { color: var(--cyan); border-color: var(--cyan); }
.chip.active { background: linear-gradient(135deg, #4fc3f7, #ab47bc); color: #fff; border-color: transparent; }
.chip.danger:hover { color: var(--danger); border-color: var(--danger); }

/* Overlay */
.overlay {
    position: absolute; inset: 0; display: flex; flex-direction: column;
    align-items: center; justify-content: center; gap: .8rem;
    background: rgba(10, 14, 26, 0.82); border-radius: 10px;
    text-align: center; padding: 1.5rem; z-index: 10;
}
.overlay h1 { font-size: 1.8rem; }
.controls-hint { font-size: .9rem; color: var(--text-dim); }
.overlay button, #startBtn {
    background: linear-gradient(135deg, #4fc3f7, #ab47bc); color: #fff; border: none;
    padding: .7rem 1.8rem; border-radius: 10px; font-size: 1rem; cursor: pointer; font-weight: 600;
    transition: transform .1s;
}
.overlay button:hover, #startBtn:hover { transform: translateY(-2px); }
.overlay button.secondary { background: transparent; border: 1px solid var(--cyan); color: var(--cyan); }

/* SEO */
.seo-section { max-width: 820px; margin: 2rem auto; padding: 0 1.2rem 3rem; }
.seo-card { background: var(--card); border: 1px solid var(--border); border-radius: 16px; padding: 1.8rem 2rem; }
.seo-card h2 { font-size: 1.4rem; margin-bottom: .8rem; color: var(--cyan); }
.seo-card h3 { font-size: 1.1rem; margin: 1.2rem 0 .5rem; color: var(--purple); }
.seo-card p, .seo-card li { color: var(--text-dim); line-height: 1.7; font-size: .95rem; }
.seo-card ul { padding-left: 1.3rem; margin: .4rem 0; }
.seo-card li { margin: .25rem 0; }

/* 移动端 */
@media (max-width: 600px) {
    .nav-inner { padding: 0 1rem; }
    #game-area { padding: .8rem .5rem; }
    #menu-bar { gap: .5rem; }
    .chip { padding: .3rem .6rem; font-size: .8rem; }
}