:root {
    --bg-color: #121212;
    --card-bg: #1E1E1E;
    --text-primary: #FFFFFF;
    --text-secondary: #AAAAAA;
    --accent-blue: #29B6F6;
    --accent-green: #00E676;
    --accent-red: #FF1744;
    --accent-yellow: #FFEA00;
    --gray-dark: #2A2A2A;
    --shadow-color: rgba(0, 0, 0, 0.5);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Inter', sans-serif;
    user-select: none;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    min-height: 100vh;
}

.app-container {
    width: 100%;
    max-width: 600px;
    display: flex;
    flex-direction: column;
    padding: 16px;
    position: relative;
}

/* Header & Settings */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 0;
}

.app-title {
    font-size: 20px;
    font-weight: 900;
    color: var(--text-primary);
    letter-spacing: 1px;
}

.header-icons {
    display: flex;
    gap: 16px;
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.2s;
}
.icon-btn:hover {
    color: var(--text-primary);
}

/* Main Indicator */
.result-container {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 32px 0 48px 0;
}

.indicator {
    width: 220px;
    height: 220px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.1s ease-out;
}

.indicator.waiting {
    background-color: var(--gray-dark);
    box-shadow: none;
}
.indicator.waiting #indicatorText {
    font-size: 24px;
    color: var(--text-secondary);
    font-weight: 900;
}

.indicator.positive {
    background-color: var(--accent-green);
    box-shadow: 0 0 40px rgba(0, 230, 118, 0.4);
}
.indicator.positive #indicatorText {
    font-size: 120px;
    color: var(--bg-color);
    font-weight: 900;
}

.indicator.negative {
    background-color: var(--accent-red);
    box-shadow: 0 0 40px rgba(255, 23, 68, 0.4);
}
.indicator.negative #indicatorText {
    font-size: 120px;
    color: var(--bg-color);
    font-weight: 900;
}

/* Cards */
.card {
    background-color: var(--card-bg);
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 24px;
    box-shadow: 0 8px 16px var(--shadow-color);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}

.card-header h2 {
    font-size: 18px;
    color: #E0E0E0;
}

.input-level {
    font-size: 14px;
    color: var(--text-secondary);
}

/* Generator Controls */
.controls {
    display: flex;
    align-items: center;
    gap: 8px;
}

.play-btn .material-icons {
    font-size: 36px;
}
.play-btn.playing {
    color: var(--accent-green);
}

.invert-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    font-size: 20px;
    font-weight: bold;
    background-color: transparent;
    transition: all 0.2s;
}
.invert-btn.inverted {
    background-color: var(--accent-red);
    color: white;
}

/* Frequencies */
.frequencies {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.freq-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 16px;
    cursor: pointer;
    padding: 8px;
    transition: all 0.2s;
}
.freq-btn:hover {
    color: var(--text-primary);
}
.freq-btn.active {
    color: var(--accent-blue);
    font-weight: bold;
}

/* VU Meter */
.vu-meter {
    display: flex;
    justify-content: space-between;
    height: 24px;
    width: 100%;
    margin-bottom: 12px;
}

.vu-segment {
    flex: 1;
    height: 100%;
    background-color: var(--gray-dark);
    margin: 0 1px;
    transition: background-color 0.05s;
}
.vu-segment.active-green { background-color: var(--accent-green); }
.vu-segment.active-yellow { background-color: var(--accent-yellow); }
.vu-segment.active-red { background-color: var(--accent-red); }

/* Slider */
.threshold-control {
    display: flex;
    flex-direction: column;
}

input[type=range] {
    -webkit-appearance: none;
    width: 100%;
    background: transparent;
    margin: 12px 0;
}
input[type=range]:focus { outline: none; }
input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: var(--text-secondary);
    border-radius: 2px;
}
input[type=range]::-webkit-slider-thumb {
    height: 16px;
    width: 16px;
    border-radius: 50%;
    background: var(--accent-blue);
    cursor: pointer;
    -webkit-appearance: none;
    margin-top: -6px;
}
input[type=range]::-moz-range-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: var(--text-secondary);
    border-radius: 2px;
}
input[type=range]::-moz-range-thumb {
    height: 16px;
    width: 16px;
    border-radius: 50%;
    background: var(--accent-blue);
    cursor: pointer;
    border: none;
}

.threshold-labels {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: var(--text-secondary);
}
.threshold-value {
    color: var(--accent-blue);
    font-weight: bold;
    font-size: 14px;
}

.hint {
    font-size: 11px;
    color: #666;
    margin-top: 4px;
}

/* Footer */
.footer {
    margin-top: auto;
    padding-bottom: 16px;
    text-align: center;
}
.footer p {
    font-size: 11px;
    color: var(--text-secondary);
    line-height: 1.5;
}
.footer a {
    color: var(--accent-blue);
    text-decoration: none;
}
.footer a:hover {
    text-decoration: underline;
}

/* Modals */
.overlay {
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background-color: rgba(18, 18, 18, 0.9);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}
.overlay.hidden {
    display: none;
}
.overlay-content {
    background-color: var(--card-bg);
    border-radius: 12px;
    padding: 32px;
    text-align: center;
    max-width: 400px;
    width: 90%;
    box-shadow: 0 8px 32px rgba(0,0,0,0.8);
}
.text-left {
    text-align: left;
}
.overlay-content h1 {
    font-size: 24px;
    margin-bottom: 24px;
}
.overlay-content p {
    font-size: 16px;
    color: #CCC;
    line-height: 1.5;
    margin-bottom: 48px;
}
.btn-primary {
    background-color: var(--accent-green);
    color: var(--bg-color);
    border: none;
    padding: 12px 24px;
    font-size: 16px;
    font-weight: bold;
    border-radius: 24px;
    cursor: pointer;
    transition: opacity 0.2s;
}
.btn-primary:hover {
    opacity: 0.9;
}
.btn-text {
    background: none;
    border: none;
    color: var(--accent-blue);
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    padding: 8px 16px;
}
.error-text {
    color: var(--accent-red);
    margin-top: 16px;
    font-size: 14px;
}
.lang-option {
    padding: 12px 0;
    font-size: 16px;
    color: var(--text-primary);
    cursor: pointer;
    border-bottom: 1px solid var(--gray-dark);
}
.lang-option:last-child {
    border-bottom: none;
}
.lang-option:hover {
    color: var(--accent-blue);
}