:root {
    --bg-color: #0d1117;
    --panel-bg: rgba(22, 27, 34, 0.95);
    --accent-blue: #58a6ff;
    --correct-green: #39ff14;
    --error-red: #ff4444;
}

body {
    background-color: var(--bg-color);
    color: #c9d1d9;
    font-family: 'Fira Code', 'Consolas', monospace;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    overflow: hidden;
}

#game-container {
    text-align: center;
    border: 1px solid #30363d;
    padding: 50px;
    background: var(--panel-bg);
    box-shadow: 0 0 40px rgba(0, 0, 0, 0.8);
    border-radius: 12px;
    min-width: 750px;
}

h1 { color: var(--accent-blue); letter-spacing: 8px; margin-bottom: 40px; font-size: 2.5rem; }

/* ボタンデザイン */
.btn-gradient {
    display: inline-block;
    padding: 12px 25px;
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.4);
    background-image: linear-gradient(to right, #70dafa 0%, #937df7 100%);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
    transition: 0.3s;
    cursor: pointer;
    font-family: inherit;
    font-weight: bold;
    margin: 8px;
    min-width: 170px;
    text-transform: uppercase;
}

.btn-gradient span { position: relative; z-index: 2; }

.btn-gradient:hover:not(:disabled) {
    transform: translate(0, -3px);
    box-shadow: 0 8px 20px rgba(250, 112, 154, 0.4);
    filter: brightness(1.1);
    border-color: #fff;
}

.btn-gradient.active {
    border: 2px solid var(--correct-green);
    box-shadow: 0 0 20px rgba(57, 255, 20, 0.6);
    transform: scale(1.05);
}

#start-btn.btn-gradient {
    background-image: linear-gradient(to right, #00f3ff 10%, #39ff14 90%);
    width: 80%;
    font-size: 1.6rem;
    margin-top: 40px;
}

#start-btn:disabled {
    filter: grayscale(1);
    opacity: 0.2;
    cursor: not-allowed;
    transform: none;
}

/* 文字の基本状態（未入力） */
#word-display span {
    display: inline-block;
    min-width: 0.6em;
    color: #888; /* 未入力はグレー */
    border-bottom: 2px solid transparent;
}

/* 現在入力すべき文字 */
#word-display span.current {
    color: #fff;
    border-bottom: 2px solid #00ffcc;
}

/* 正解した文字（緑色） */
#word-display span.cleared {
    color: #00ff00;
}

/* 間違えた文字（赤い背景） */
#word-display span.miss {
    background-color: #ff0000;
    color: #ffffff;
}

.selection-group { margin-bottom: 30px; }
.label { font-size: 0.8rem; color: #8b949e; margin-bottom: 12px; letter-spacing: 2px; }

/* ゲーム表示 */
#game-info { font-size: 1rem; color: var(--accent-blue); margin-bottom: 20px; }
#word-display { font-size: 4rem; margin-bottom: 30px; min-height: 1.2em; }
#word-display span { position: relative; padding: 0 2px; }
#timer-display { font-size: 1.5rem; color: #8b949e; }

/* タイピング状態 */
.current { border-bottom: 4px solid var(--accent-blue); }
.correct { color: var(--correct-green); text-shadow: 0 0 10px var(--correct-green); }
.incorrect { color: var(--error-red); text-shadow: 0 0 15px var(--error-red); animation: shake 0.1s; }

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(5px); }
    75% { transform: translateX(-5px); }
}