/* ========================================
   霓虹貪食蛇 - 賽博朋克風格樣式
   ======================================== */

/* --- CSS 變數 (Design Tokens) --- */
:root {
    /* 主色調 */
    --color-bg: #0a0f1a;
    --color-bg-secondary: #0d1424;
    --color-snake: #00ff88;
    --color-food: #ff006e;
    --color-text: #00d4ff;
    --color-accent: #8b5cf6;
    --color-white: #ffffff;
    --color-danger: #ff3366;

    /* 發光效果 */
    --glow-snake: 0 0 10px #00ff88, 0 0 20px #00ff88, 0 0 40px #00ff88;
    --glow-food: 0 0 10px #ff006e, 0 0 20px #ff006e, 0 0 40px #ff006e;
    --glow-text: 0 0 10px #00d4ff, 0 0 20px #00d4ff;
    --glow-accent: 0 0 10px #8b5cf6, 0 0 20px #8b5cf6;

    /* 字體 */
    --font-main: 'Orbitron', sans-serif;

    /* 間距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* 過渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html,
body {
    width: 100%;
    height: 100%;
    overflow: hidden;
}

body {
    font-family: var(--font-main);
    background: var(--color-bg);
    color: var(--color-text);
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

/* --- 粒子背景 --- */
#particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
    background:
        radial-gradient(ellipse at 20% 80%, rgba(139, 92, 246, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 20%, rgba(0, 212, 255, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(0, 255, 136, 0.05) 0%, transparent 60%);
}

/* 格線背景 */
#particles::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        linear-gradient(rgba(0, 212, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 212, 255, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: gridMove 20s linear infinite;
}

@keyframes gridMove {
    0% {
        transform: translate(0, 0);
    }

    100% {
        transform: translate(50px, 50px);
    }
}

/* --- 遊戲容器 --- */
#game-container {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 600px;
    padding: var(--spacing-md);
}

/* --- 畫面切換 --- */
.screen {
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.5s ease;
}

.screen.active {
    display: flex;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* --- 標題 --- */
.title {
    font-size: clamp(2.5rem, 8vw, 4rem);
    font-weight: 900;
    color: var(--color-text);
    text-transform: uppercase;
    text-shadow: var(--glow-text);
    letter-spacing: 0.2em;
    margin-bottom: var(--spacing-xs);
    position: relative;
}

/* Glitch 動畫效果 */
.glitch {
    animation: glitch 3s infinite;
}

.glitch::before,
.glitch::after {
    content: attr(data-text);
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
}

.glitch::before {
    color: var(--color-food);
    animation: glitchTop 2s infinite;
    clip-path: polygon(0 0, 100% 0, 100% 33%, 0 33%);
}

.glitch::after {
    color: var(--color-snake);
    animation: glitchBottom 2s infinite;
    clip-path: polygon(0 67%, 100% 67%, 100% 100%, 0 100%);
}

@keyframes glitch {

    0%,
    100% {
        transform: translate(0);
    }

    20% {
        transform: translate(-2px, 2px);
    }

    40% {
        transform: translate(-2px, -2px);
    }

    60% {
        transform: translate(2px, 2px);
    }

    80% {
        transform: translate(2px, -2px);
    }
}

@keyframes glitchTop {

    0%,
    100% {
        transform: translate(0);
    }

    50% {
        transform: translate(3px, 0);
    }
}

@keyframes glitchBottom {

    0%,
    100% {
        transform: translate(0);
    }

    50% {
        transform: translate(-3px, 0);
    }
}

.subtitle {
    font-size: 1.2rem;
    color: var(--color-accent);
    text-shadow: var(--glow-accent);
    margin-bottom: var(--spacing-lg);
    letter-spacing: 0.3em;
}

/* --- 難度選擇器 --- */
.difficulty-selector {
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.difficulty-selector .label {
    font-size: 0.9rem;
    color: rgba(0, 212, 255, 0.7);
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 0.2em;
}

.difficulty-buttons {
    display: flex;
    gap: var(--spacing-sm);
}

.difficulty-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(0, 212, 255, 0.05);
    border: 1px solid rgba(0, 212, 255, 0.2);
    border-radius: 12px;
    color: var(--color-text);
    font-family: var(--font-main);
    font-size: 0.8rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.difficulty-btn .icon {
    font-size: 1.5rem;
    margin-bottom: 4px;
}

.difficulty-btn:hover {
    background: rgba(0, 212, 255, 0.1);
    border-color: var(--color-text);
    transform: translateY(-2px);
}

.difficulty-btn.active {
    background: rgba(0, 255, 136, 0.15);
    border-color: var(--color-snake);
    color: var(--color-snake);
    box-shadow: var(--glow-snake);
}

/* --- 霓虹按鈕 --- */
.neon-btn {
    position: relative;
    padding: var(--spacing-sm) var(--spacing-xl);
    background: transparent;
    border: 2px solid var(--color-snake);
    border-radius: 50px;
    color: var(--color-snake);
    font-family: var(--font-main);
    font-size: 1rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    cursor: pointer;
    overflow: hidden;
    transition: all var(--transition-normal);
    box-shadow: var(--glow-snake);
}

.neon-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(0, 255, 136, 0.3), transparent);
    transition: left 0.5s ease;
}

.neon-btn:hover {
    background: rgba(0, 255, 136, 0.1);
    transform: scale(1.05);
}

.neon-btn:hover::before {
    left: 100%;
}

.neon-btn:active {
    transform: scale(0.98);
}

.neon-btn.secondary {
    border-color: var(--color-accent);
    color: var(--color-accent);
    box-shadow: var(--glow-accent);
    margin-top: var(--spacing-sm);
}

.neon-btn.secondary:hover {
    background: rgba(139, 92, 246, 0.1);
}

/* --- 分數顯示 --- */
.high-score-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-top: var(--spacing-lg);
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(255, 0, 110, 0.1);
    border: 1px solid rgba(255, 0, 110, 0.3);
    border-radius: 12px;
}

.high-score-display .label {
    font-size: 0.7rem;
    color: rgba(255, 0, 110, 0.8);
    text-transform: uppercase;
    letter-spacing: 0.2em;
}

.high-score-display .score {
    font-size: 1.8rem;
    font-weight: 900;
    color: var(--color-food);
    text-shadow: var(--glow-food);
}

/* --- 控制提示 --- */
.controls-hint {
    margin-top: var(--spacing-lg);
    text-align: center;
    font-size: 0.75rem;
    color: rgba(0, 212, 255, 0.5);
}

.controls-hint p {
    margin: 4px 0;
}

kbd {
    display: inline-block;
    padding: 2px 8px;
    background: rgba(0, 212, 255, 0.1);
    border: 1px solid rgba(0, 212, 255, 0.3);
    border-radius: 4px;
    font-family: var(--font-main);
    font-size: 0.7rem;
    margin: 0 2px;
}

/* --- 倒數畫面 --- */
#countdown-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 15, 26, 0.9);
    z-index: 100;
}

.countdown-number {
    font-size: 10rem;
    font-weight: 900;
    color: var(--color-text);
    text-shadow: var(--glow-text);
    animation: countdownPulse 1s ease infinite;
}

@keyframes countdownPulse {

    0%,
    100% {
        transform: scale(1);
        opacity: 1;
    }

    50% {
        transform: scale(1.2);
        opacity: 0.8;
    }
}

/* --- 遊戲畫面 --- */
.game-header {
    display: flex;
    justify-content: space-between;
    width: 100%;
    margin-bottom: var(--spacing-sm);
}

.score-box {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(0, 212, 255, 0.05);
    border: 1px solid rgba(0, 212, 255, 0.2);
    border-radius: 8px;
}

.score-box .label {
    font-size: 0.65rem;
    color: rgba(0, 212, 255, 0.7);
    text-transform: uppercase;
    letter-spacing: 0.15em;
}

.score-box .score {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
    text-shadow: var(--glow-text);
}

.score-box.high {
    border-color: rgba(255, 0, 110, 0.3);
    background: rgba(255, 0, 110, 0.05);
}

.score-box.high .label {
    color: rgba(255, 0, 110, 0.7);
}

.score-box.high .score {
    color: var(--color-food);
    text-shadow: var(--glow-food);
}

/* --- Canvas 容器 --- */
#canvas-wrapper {
    position: relative;
    border: 2px solid var(--color-accent);
    border-radius: 8px;
    box-shadow: var(--glow-accent);
    overflow: hidden;
}

#game-canvas {
    display: block;
    background: var(--color-bg-secondary);
}

/* --- 暫停覆蓋層 --- */
.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 15, 26, 0.85);
    display: flex;
    justify-content: center;
    align-items: center;
    backdrop-filter: blur(4px);
    transition: opacity var(--transition-normal);
}

.overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.overlay-content {
    text-align: center;
}

.overlay-content h2 {
    font-size: 2rem;
    color: var(--color-text);
    text-shadow: var(--glow-text);
    margin-bottom: var(--spacing-sm);
}

.overlay-content p {
    color: rgba(0, 212, 255, 0.7);
}

/* --- Game Over 畫面 --- */
.gameover-title {
    font-size: clamp(2rem, 6vw, 3rem);
    font-weight: 900;
    color: var(--color-danger);
    text-shadow: 0 0 10px var(--color-danger), 0 0 20px var(--color-danger);
    margin-bottom: var(--spacing-lg);
    letter-spacing: 0.15em;
}

/* 震動動畫 */
.shake {
    animation: shake 0.5s ease-in-out;
}

@keyframes shake {

    0%,
    100% {
        transform: translateX(0);
    }

    10%,
    30%,
    50%,
    70%,
    90% {
        transform: translateX(-10px);
    }

    20%,
    40%,
    60%,
    80% {
        transform: translateX(10px);
    }
}

.final-scores {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.score-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.score-item .label {
    font-size: 0.75rem;
    color: rgba(0, 212, 255, 0.7);
    text-transform: uppercase;
    letter-spacing: 0.2em;
}

.score-item .score {
    font-size: 2.5rem;
    font-weight: 900;
    color: var(--color-text);
    text-shadow: var(--glow-text);
}

.score-item .badge {
    font-size: 1.2rem;
    color: #ffd700;
    text-shadow: 0 0 10px #ffd700, 0 0 20px #ffd700;
    animation: pulse 1s ease infinite;
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.1);
    }
}

.hidden {
    display: none !important;
}

/* --- 響應式設計 --- */
@media (max-width: 480px) {
    #game-container {
        padding: var(--spacing-sm);
    }

    .difficulty-buttons {
        flex-wrap: wrap;
        justify-content: center;
    }

    .neon-btn {
        padding: var(--spacing-sm) var(--spacing-lg);
        font-size: 0.85rem;
    }
}

/* --- 觸控設備輔助 --- */
@media (hover: none) {

    .difficulty-btn:hover,
    .neon-btn:hover {
        transform: none;
    }
}