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

body {
    font-family: -apple-system, BlinkMacSystemFont, sans-serif;
    background: black;
    color: white;
    overflow: hidden;
    position: relative;
}

.screen {
    display: none;
    height: 100vh;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

.screen.active {
    display: flex;
}

.title {
    font-size: 3rem;
    font-weight: 100;
    letter-spacing: 3px;
    opacity: 0.85;
    margin-bottom: 1rem;
}

.subtitle {
    font-size: 1.2rem;
    font-weight: 100;
    letter-spacing: 1px;
    margin-bottom: 3rem;
    opacity: 0.3;
    text-align: center;
}

.buttons {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    width: 300px;
}

.routine-btn {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.08) 0%, rgba(255, 255, 255, 0.04) 100%);
    border: 0.5px solid rgba(255, 255, 255, 0.1);
    border-radius: 16px;
    color: white;
    font-size: 1.2rem;
    padding: 16px 24px;
    cursor: pointer;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.4);
}

.routine-btn:hover {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.12) 0%, rgba(255, 255, 255, 0.06) 100%);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.5);
}

.routine-btn.secondary {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.03) 0%, rgba(255, 255, 255, 0.01) 100%);
    border: 0.5px solid rgba(255, 255, 255, 0.06);
    color: rgba(255, 255, 255, 0.7);
    font-size: 1rem;
}

.routine-btn.secondary:hover {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.06) 0%, rgba(255, 255, 255, 0.02) 100%);
    color: rgba(255, 255, 255, 0.85);
}

.divider {
    width: 100px;
    height: 1px;
    background: rgba(255, 255, 255, 0.1);
    margin: 2rem auto 1.5rem auto;
}

.learn-more {
    color: rgba(255, 255, 255, 0.5);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 400;
    letter-spacing: 0.2px;
    transition: color 0.2s ease;
}

.learn-more:hover {
    color: rgba(255, 255, 255, 0.8);
}

.session-header {
    text-align: center;
    margin-bottom: 2rem;
    min-height: 120px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.exercise-name {
    font-size: 1.25rem;
    font-weight: 500;
    opacity: 0.5;
    margin-bottom: 1rem;
}

.phase-label {
    font-size: 2.2rem;
    font-weight: 300;
    letter-spacing: 1.5px;
    opacity: 0.95;
}

.breathing-circle-container {
    position: relative;
    margin: 2rem 0;
}

.breathing-circle {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(255, 255, 255, 0.16) 0%, transparent 70%);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    transition: transform 0.1s cubic-bezier(0.4, 0.0, 0.2, 1), opacity 0.1s ease;
    filter: blur(0.3px);
    will-change: transform, opacity;
}

.breathing-circle::before {
    content: '';
    position: absolute;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(0, 0, 0, 0.3) 0%, transparent 70%);
    filter: blur(20px);
    z-index: -1;
}

.phase-count {
    font-size: 7.5rem;
    font-weight: 100;
    letter-spacing: 2px;
    opacity: 0.4;
}

.stop-btn {
    background: rgba(255, 255, 255, 0.04);
    border: 0.5px solid rgba(255, 255, 255, 0.1);
    border-radius: 14px;
    color: rgba(255, 255, 255, 0.5);
    font-size: 1rem;
    padding: 14px 48px;
    cursor: pointer;
    margin-top: 2rem;
}

.stop-btn:hover {
    background: rgba(255, 255, 255, 0.08);
    color: rgba(255, 255, 255, 0.7);
}

@media (max-width: 768px) {
    .title {
        font-size: 2.5rem;
    }

    .buttons {
        width: 250px;
    }

    .breathing-circle {
        width: 250px;
        height: 250px;
    }

    .breathing-circle::before {
        width: 250px;
        height: 250px;
    }

    .phase-count {
        font-size: 6rem;
    }
}