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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: white;
    overflow: hidden;
}

/* 인트로 화면 */
.intro-screen {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    width: 100%;
}

.intro-screen h1 {
    font-size: 4rem;
    text-shadow: 0 0 30px rgba(255, 200, 0, 0.5);
    color: #ffd700;
    margin-bottom: 50px;
}

.intro-btn {
    padding: 25px 80px;
    font-size: 2rem;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: bold;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.intro-btn:hover {
    transform: scale(1.1);
    box-shadow: 0 15px 40px rgba(102, 126, 234, 0.5);
}

/* 게임 화면 */
.game-screen {
    display: none;
    flex-direction: column;
    width: 100%;
    height: 100vh;
    padding: 20px;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    padding: 0 20px;
    margin-bottom: 10px;
}

.header h1 {
    font-size: 2rem;
    text-shadow: 0 0 20px rgba(255, 200, 0, 0.5);
    color: #ffd700;
}

.header .round-info {
    font-size: 1.2rem;
    color: #aaa;
}

.header .round-number {
    color: #4ecdc4;
    font-weight: bold;
}

.main-area {
    display: flex;
    flex-direction: column;
    width: 100%;
}

.display-box {
    background: #000;
    border-radius: 20px;
    height: calc(100vh - 180px);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 15px;
    border: 4px solid #333;
    overflow: hidden;
    position: relative;
}

.countdown-text {
    font-size: 12rem;
    font-weight: bold;
    color: #ff6b6b;
    text-shadow: 0 0 50px rgba(255, 107, 107, 0.8);
    animation: pulse 0.5s ease-in-out;
}

.message-text {
    font-size: 3.5rem;
    font-weight: bold;
    color: #4ecdc4;
    text-shadow: 0 0 30px rgba(78, 205, 196, 0.8);
    text-align: center;
    padding: 20px;
    animation: shake 0.5s ease-in-out;
}

.end-text {
    font-size: 10rem;
    font-weight: bold;
    color: #ffd700;
    text-shadow: 0 0 50px rgba(255, 215, 0, 0.8);
    animation: pulse 1s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.2); }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-10px); }
    75% { transform: translateX(10px); }
}

.display-box img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

.controls {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
    padding: 10px 0;
}

button {
    padding: 15px 40px;
    font-size: 1.3rem;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: bold;
}

.start-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.start-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 10px 30px rgba(102, 126, 234, 0.4);
}

.start-btn:disabled {
    background: #555;
    cursor: not-allowed;
    transform: none;
}

.reset-btn {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
}

.reset-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 10px 30px rgba(79, 172, 254, 0.4);
}

.ready-text {
    font-size: 2.5rem;
    color: #666;
}