:root {
    --bg-color: #121212;
    --primary-color: #ffffff;
    --secondary-color: #b3b3b3;
    --accent-color: #1db954;
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
}

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

body {
    /* font-family: 'Poppins', sans-serif; */
    font-family: 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--primary-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
}

#app-container {
    width: 100%;
    height: 100vh;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

#background-visualizer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    background: radial-gradient(circle, rgba(29, 185, 84, 0.1) 0%, rgba(18, 18, 18, 0) 70%);
    transition: background 0.5s ease-out;
}

#main-content {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 40px;
    padding: 20px;
}

#presets-container {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

.preset-item {
    cursor: pointer;
    padding: 15px;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 50%;
    width: 80px;
    height: 80px;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.preset-item:hover, .preset-item.active {
    background: rgba(255, 255, 255, 0.1);
    transform: scale(1.1);
    border-color: var(--accent-color);
}

.preset-item img {
    width: 40px;
    height: 40px;
    filter: invert(1);
}

#player-circle {
    position: relative;
    width: 220px;
    height: 220px;
    display: flex;
    justify-content: center;
    align-items: center;
}

#progress-ring {
    position: absolute;
    top: 0;
    left: 0;
    transform: rotate(-90deg);
}

.progress-ring__bg {
    fill: none;
    stroke: var(--glass-bg);
    stroke-width: 8;
}

.progress-ring__fg {
    fill: none;
    stroke: var(--accent-color);
    stroke-width: 8;
    stroke-linecap: round;
    transition: stroke-dashoffset 1s linear;
}

#timer-display {
    font-size: 3rem;
    font-weight: 300;
    color: var(--primary-color);
}

#play-pause-button {
    position: absolute;
    bottom: -10px;
    width: 60px;
    height: 60px;
    cursor: pointer;
    background: var(--accent-color);
    border-radius: 50%;
    padding: 15px;
    transition: all 0.2s ease;
    box-shadow: 0 4px 20px rgba(29, 185, 84, 0.4);
}

#play-pause-button:hover {
    transform: scale(1.1);
}

#timer-presets-container {
    display: flex;
    gap: 15px;
}

.timer-preset {
    cursor: pointer;
    padding: 8px 15px;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    color: var(--secondary-color);
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.timer-preset:hover, .timer-preset.active {
    background: var(--accent-color);
    color: var(--bg-color);
    /* font-weight: 600; */
    border-color: var(--accent-color);
}

@media (max-width: 600px) {
    #main-content {
        gap: 30px;
    }
    #presets-container {
        gap: 10px;
    }
    .preset-item {
        width: 55px;
        height: 55px;
    }
    .preset-item img {
        width: 28px;
        height: 28px;
    }
    #player-circle {
        width: 180px;
        height: 180px;
    }
    #progress-ring {
        width: 180px;
        height: 180px;
    }
    .progress-ring__bg, .progress-ring__fg {
        cx: 90;
        cy: 90;
        r: 80;
    }
    #timer-display {
        font-size: 2.5rem;
    }
    #play-pause-button {
        width: 50px;
        height: 50px;
        padding: 12px;
        bottom: -5px;
    }
}