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

/* ---------- Themes ---------- */

:root {
    --bg: #fdf8ec;
    --text: #1a1005;
    --cell-bg: #f0e6c8;
    --cell-border: #a08030;
    --cell-active: #e0d4a8;
    --label: #6b5520;
    --overlay-bg: rgba(26, 16, 5, 0.8);
    --overlay-text: #fdf8ec;
    --error: #c02010;
    --white-piece: #c02818;
    --black-piece: #082e5c;
    --selected: #1a1005;
    --target: #186830;
    --result: #c02818;
    --win-shadow: #ffffff;
    --win-shadow-width: 6;
}

[data-theme="dark"] {
    --bg: #0a0a12;
    --text: #e0e0f0;
    --cell-bg: #1a1a2e;
    --cell-border: #2a2a44;
    --cell-active: #2a2a44;
    --label: #5a5a7a;
    --overlay-bg: rgba(10, 10, 18, 0.92);
    --overlay-text: #8888aa;
    --error: #ff6b8a;
    --white-piece: #ff6b8a;
    --black-piece: #6bb3ff;
    --selected: #ffd966;
    --target: #66cc99;
    --result: #ffd966;
    --win-shadow: rgba(0, 0, 0, 0.3);
    --win-shadow-width: 7;
}

/* ---------- Base ---------- */

body {
    background: var(--bg);
    color: var(--text);
    font-family:
        system-ui,
        -apple-system,
        "Segoe UI",
        Roboto,
        "Helvetica Neue",
        Arial,
        sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
}

h1 {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    text-align: center;
    line-height: 36px;
    padding: 16px 0 8px;
    background: var(--bg);
    z-index: 5;
}

@media (max-width: 480px) {
    #app {
        max-width: none;
        padding: 12px 16px;
    }
}

#app {
    width: 100%;
    max-width: 420px;
    padding: 56px 8px 12px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    position: relative;
}

/* ---------- Title & Status ---------- */

h1 {
    font-size: 18px;
    font-weight: 600;
    letter-spacing: 1px;
    margin-bottom: 4px;
}

#turn-indicator {
    font-size: 15px;
    min-height: 20px;
    margin-bottom: 4px;
    text-align: center;
}

.rematch-area {
    margin-top: 8px;
    font-size: 14px;
    color: var(--label);
    text-align: center;
}

.rematch-btn {
    background: var(--cell-bg);
    border: 1px solid var(--cell-border);
    color: var(--text);
    padding: 10px 28px;
    border-radius: 8px;
    font-family: inherit;
    font-size: 16px;
    cursor: pointer;
    margin-left: 8px;
}

.rematch-btn:active {
    background: var(--cell-active);
}

.leave-btn {
    background: transparent;
    border-color: transparent;
    font-size: 14px;
    color: var(--label);
    padding: 8px 16px;
}

#error-message {
    font-size: 13px;
    min-height: 18px;
    color: var(--error);
}

/* ---------- Theme Switcher ---------- */

#exit-btn {
    position: fixed;
    top: 16px;
    left: 16px;
    z-index: 20;
    background: transparent;
    border: 1px solid var(--label);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    color: var(--label);
    font-family: inherit;
}

#exit-btn.visible {
    display: flex;
}

#theme-toggle {
    position: fixed;
    top: 16px;
    right: 16px;
    z-index: 20;
    background: transparent;
    border: 1px solid var(--label);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition:
        background 0.2s,
        border-color 0.2s;
}

#theme-toggle svg {
    width: 18px;
    height: 18px;
    fill: var(--label);
    color: var(--label);
}

/* ---------- Overlays ---------- */

#overlay {
    position: fixed;
    inset: 0;
    background: var(--overlay-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    font-size: 16px;
    color: var(--overlay-text);
}

#overlay.hidden {
    display: none;
}

/* ---------- Game Area ---------- */

#game-area {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

#game-area .hand-panel:first-child {
    margin-bottom: 8px;
}

#game-area .hand-panel:last-child {
    margin-top: 8px;
}

/* ---------- Hand Panels ---------- */

.hand-panel {
    display: grid;
    grid-template-columns: 28px repeat(4, 1fr) 28px;
    gap: 12px;
    align-items: center;
    width: 100%;
    padding: 0 4px;
}

.hand-cell {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--cell-border);
    border-radius: 8px;
    background: var(--cell-bg);
    font-size: 46px;
    cursor: pointer;
    transition: border-color 0.15s;
}

.hand-cell:active {
    background: var(--cell-active);
}

.hand-cell.selected {
    border-color: var(--selected);
}

.hand-cell.empty {
    cursor: default;
}

.hand-cell.empty:active {
    background: var(--cell-bg);
}

/* ---------- Column Labels ---------- */

.col-labels {
    display: grid;
    grid-template-columns: 28px repeat(4, 1fr) 28px;
    gap: 12px;
    width: 100%;
    padding: 0 4px;
}

.col-labels span {
    text-align: center;
    font-size: 13px;
    color: var(--label);
}

/* ---------- Board ---------- */

.board {
    position: relative;
    display: grid;
    grid-template-columns: 28px repeat(4, 1fr) 28px;
    gap: 12px;
    align-items: center;
    width: 100%;
    padding: 0 4px;
}

.row-label {
    font-size: 13px;
    color: var(--label);
}

.row-label:nth-child(6n + 1) {
    text-align: right;
}

.row-label:nth-child(6n) {
    text-align: left;
}

.board-cell {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--cell-border);
    border-radius: 8px;
    background: var(--cell-bg);
    font-size: 46px;
    cursor: pointer;
    transition: border-color 0.15s;
}

.board-cell:active {
    background: var(--cell-active);
}

.board-cell.selected {
    border-color: var(--selected);
}

.board-cell.target {
    border-color: var(--target);
}

.win-line {
    position: absolute;
    top: 0;
    left: 0;
    pointer-events: none;
}

.win-line line.shadow {
    stroke: var(--win-shadow);
    stroke-width: var(--win-shadow-width);
    stroke-linecap: round;
}

.win-line line.main {
    stroke-width: 4;
    stroke-linecap: round;
}

.win-line.piece-white line.main {
    stroke: var(--white-piece);
}

.win-line.piece-black line.main {
    stroke: var(--black-piece);
}

/* ---------- Piece Colors ---------- */

.piece-white {
    color: var(--white-piece);
}

.piece-black {
    color: var(--black-piece);
}

.game-result {
    color: var(--result);
}