:root {
    --bg-color: #f9f9f9;
    --text-color: #333;
    --container-bg-color: #fff;
    --container-shadow: 0 8px 30px rgba(0,0,0,0.1);
    --title-color: #000;
    --status-color: #555;
    --score-color: #777;
    --board-bg-color: #f0e5d8;
    --board-border-color: #e0d5c8;
    --line-color: #c8bbae;
    --piece-shadow: 0 2px 5px rgba(0,0,0,0.2);
    --black-piece-bg: #333;
    --white-piece-bg: #fff;
    --white-piece-border: #ddd;
    --button-bg-color: #007aff;
    --button-hover-bg-color: #005ecb;
    --button-text-color: #fff;
    --cancel-button-bg-color: #eee;
    --cancel-button-text-color: #333;
    --hint-border-color: #007aff;
}

.dark-theme {
    --bg-color: #1c1c1e;
    --text-color: #f2f2f7;
    --container-bg-color: #2c2c2e;
    --container-shadow: 0 8px 30px rgba(0,0,0,0.4);
    --title-color: #fff;
    --status-color: #a9a9b3;
    --score-color: #8e8e93;
    --board-bg-color: #3a3a3c;
    --board-border-color: #4a4a4c;
    --line-color: #5a5a5c;
    --piece-shadow: 0 2px 5px rgba(0,0,0,0.5);
    --black-piece-bg: #1c1c1e;
    --white-piece-bg: #f2f2f7;
    --white-piece-border: #5a5a5c;
    --button-bg-color: #0a84ff;
    --button-hover-bg-color: #0060df;
    --button-text-color: #fff;
    --cancel-button-bg-color: #48484a;
    --cancel-button-text-color: #f2f2f7;
    --hint-border-color: #0a84ff;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

#game-container {
    background: var(--container-bg-color);
    padding: 30px;
    border-radius: 20px;
    box-shadow: var(--container-shadow);
    max-width: 960px;
    transition: background-color 0.3s, box-shadow 0.3s;
    position: relative; /* 用于容器内绝对定位 */
}

/* 顶部信息栏（默认隐藏，仅移动端显示） */
.top-bar { display: none; }
.top-text h1 { margin: 0 0 8px 0; }
.top-tools { display: flex; gap: 10px; }

/* 固定在页面右上角的工具按钮 */
.page-tools {
    position: fixed;
    top: 12px;
    right: 12px;
    display: flex;
    gap: 10px;
    z-index: 1001;
}

/* 容器右上角工具栏 */
.container-tools {
    position: absolute;
    top: -14px;
    right: -8px;
    display: flex;
    gap: 10px;
    z-index: 20;
}

/* 按钮通用样式（合并重复定义） */
.icon-btn {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--container-bg-color);
    border: 1px solid var(--board-border-color);
    border-radius: 10px;
    box-shadow: var(--container-shadow);
    cursor: pointer;
    transition: transform 0.15s ease, background-color 0.2s ease;
    padding: 0;
}

h1 {
    color: var(--title-color);
    font-size: 2.5em;
    font-weight: 600;
    margin-bottom: 20px;
    text-align: left;
}

/* 仅供屏幕阅读器使用的隐藏元素 */
.sr-only {
    position: absolute !important;
    width: 1px; height: 1px;
    padding: 0; margin: -1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap; border: 0;
}

#status-area {
    margin-bottom: 10px;
    font-size: 1.1em;
    color: var(--status-color);
    min-height: 1.5em;
    text-align: left;
}

#score-area {
    margin-bottom: 30px;
    font-size: 1em;
    color: var(--score-color);
    text-align: left;
}

#board {
    display: block;
    width: 90vw;
    height: 90vw;
    max-width: 570px;
    max-height: 570px;
    background-color: var(--board-bg-color);
    border: 1px solid var(--board-border-color);
    position: relative;
}

#board canvas {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    display: block;
}

/* 记分板与计时器 */
.scoreboard {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 16px;
}
.scoreboard .player { display: flex; flex-direction: column; align-items: center; gap: 6px; }
.scoreboard .avatar {
    width: 40px; height: 40px; border-radius: 50%;
    box-shadow: var(--piece-shadow);
    border: 1px solid var(--board-border-color);
    position: relative;
}
.scoreboard .avatar.piece-black { background: var(--black-piece-bg); }
.scoreboard .avatar.piece-white { background: var(--white-piece-bg); border: 1px solid var(--white-piece-border); }
.scoreboard .score-digits { font-size: 1.6em; font-weight: 700; color: var(--text-color); min-width: 64px; text-align: center; }
.scoreboard .timer { font-size: 0.9em; color: var(--status-color); background: rgba(0,0,0,0.06); padding: 2px 8px; border-radius: 8px; }
.scoreboard .player.active .avatar { outline: 3px solid var(--button-bg-color); }
.scoreboard .player:not(.active) .avatar::after { display: none; }

/* 倒计时环形进度（根据 --pdeg 与 --ring-color 渲染） */
.scoreboard .avatar::after {
    content: '';
    position: absolute;
    inset: -6px; /* 环宽度 */
    border-radius: 50%;
    background: conic-gradient(var(--ring-color, var(--button-bg-color)) var(--pdeg, 360deg), rgba(0,0,0,0.12) 0);
    -webkit-mask: radial-gradient(farthest-side, transparent calc(100% - 6px), #000 0);
            mask: radial-gradient(farthest-side, transparent calc(100% - 6px), #000 0);
    pointer-events: none;
}

/* 棋盘右上角工具栏 */
.board-tools {
    position: absolute;
    top: 8px;
    right: 8px;
    display: flex;
    gap: 8px;
    z-index: 10;
}

/* 删除重复的 .icon-btn 定义，统一见上 */

/* 禁用棋盘点击（Canvas 版本） */
.board-disabled canvas { pointer-events: none; cursor: not-allowed; }
.icon-btn:hover {
    transform: translateY(-1px);
}

.icon {
    width: 22px;
    height: 22px;
    color: var(--text-color);
}

/* 旧的格子元素已移除 */

.intersection::before, .intersection::after {
    content: '';
    position: absolute;
    background-color: var(--line-color);
}

.intersection::before {
    width: 100%;
    height: 1px;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
}

.intersection::after {
    width: 1px;
    height: 100%;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
}

.piece {
    width: 85%;
    height: 85%;
    border-radius: 50%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    box-shadow: var(--piece-shadow);
    pointer-events: none; /* Make pieces unclickable */
}

.black {
    background: var(--black-piece-bg);
}

.white {
    background: var(--white-piece-bg);
    border: 1px solid var(--white-piece-border);
}

#main-game-area {
    display: flex;
    align-items: flex-start;
    justify-content: center;
    gap: 30px;
}

#sidebar {
    width: 200px;
    display: flex;
    flex-direction: column;
    position: relative; /* 让右上角图标锚定在侧栏内 */
}

#controls {
    display: flex;
    flex-direction: column;
    gap: 15px;
    width: 100%;
}

#controls button {
    padding: 12px 20px;
    font-size: 0.9em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: var(--button-text-color);
    background-color: var(--button-bg-color);
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: background-color 0.2s;
}

#controls button:hover {
    background-color: var(--button-hover-bg-color);
}

.hint {
    border: 2px solid var(--hint-border-color);
    border-radius: 50%;
    box-sizing: border-box;
}

#modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: none; /* Hidden by default */
    justify-content: center;
    align-items: center;
    z-index: 10000; /* 覆盖顶部吸顶栏与其他元素 */
}

#win-modal, #confirm-reset-modal {
    background: var(--container-bg-color);
    padding: 30px 50px;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

#win-message, #confirm-reset-message {
    font-size: 1.5em;
    margin-bottom: 20px;
    color: var(--text-color);
}

#play-again-button, #confirm-reset-button {
    padding: 10px 25px;
    font-size: 1em;
    color: var(--button-text-color);
    background-color: var(--button-bg-color);
    border: none;
    border-radius: 10px;
    cursor: pointer;
}

#win-modal-buttons, #confirm-reset-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
}

#cancel-win-button, #cancel-reset-button {
    padding: 10px 25px;
    font-size: 1em;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    color: var(--cancel-button-text-color);
    background-color: var(--cancel-button-bg-color);
}

@keyframes new-piece-animation {
    0% {
        transform: translate(-50%, -50%) scale(1.2);
    }
    50% {
        transform: translate(-50%, -50%) scale(1.5);
    }
    100% {
        transform: translate(-50%, -50%) scale(1.2);
    }
}

.new-piece {
    animation: new-piece-animation 0.4s ease-in-out;
}

/* 轮到一方时头像轻微放大 */
@keyframes avatar-pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.12); }
    100% { transform: scale(1); }
}
.scoreboard .avatar.pulse { animation: avatar-pulse 0.28s ease-in-out; }

@keyframes winning-piece-animation {
    0%, 100% {
        opacity: 1;
        transform: translate(-50%, -50%) scale(1.2);
    }
    50% {
        opacity: 0.5;
        transform: translate(-50%, -50%) scale(1.3);
    }
}

.winning-piece {
    animation: winning-piece-animation 1s infinite;
}

@media (max-width: 850px) {
    /* 限制棋盘区域触控手势，避免误触页面滚动 */
    #board { touch-action: none; }

    #game-container { padding: 16px; }

    /* 显示顶部信息栏，隐藏侧栏标题和工具 */
    .top-bar {
        display: flex;
        align-items: center;
        justify-content: center; /* 记分板居中 */
        gap: 16px;
        margin-bottom: 12px;
        position: sticky;
        top: 0;
        z-index: 5;
        background: var(--container-bg-color);
        padding-bottom: 4px;
    }
    #sidebar h1, #status-area, #score-area, #container-tools, #scoreboard-desktop { display: none; }
    /* 顶部工具保留右上角，不遮挡记分板 */
    .page-tools { right: 12px; left: auto; transform: none; top: 6px; }
    .top-bar { margin-top: 44px; }

    #main-game-area {
        flex-direction: column;
        align-items: center;
    }

    #sidebar { width: 100%; margin-top: 8px; }
    #controls { flex-direction: row; flex-wrap: nowrap; justify-content: space-between; gap: 12px; position: sticky; bottom: 12px; }
    #controls button { flex: 1 1 22%; }
}

/* 移动端适配优化 */
@media (max-width: 480px) {
    #game-container { padding: 16px; border-radius: 16px; }

    .icon-btn {
        width: 42px;
        height: 42px;
        border-radius: 12px;
    }

    .icon {
        width: 24px;
        height: 24px;
    }

    /* 棋盘略扩大占屏比例，保持方形 */
    #board {
        width: 92vw;
        height: 92vw;
        max-width: 520px;
        max-height: 520px;
    }

    h1 { font-size: 2.1em; }

    #controls { gap: 12px; }

    #controls button {
        padding: 12px 8px;
        font-size: 1em;
    }
}

/* 适配 iOS 安全区域（刘海等），仅在支持且窄屏时生效 */
@supports (top: env(safe-area-inset-top)) {
    @media (max-width: 850px) {
        .container-tools {
            top: calc(env(safe-area-inset-top) + 8px);
            right: calc(env(safe-area-inset-right) + 8px);
        }
    }
}