:root {
    --bg-color: #121212;
    --surface-color: #1e1e1e;
    --surface-light: #2d2d2d;
    --primary-color: #bb86fc;
    --primary-variant: #3700b3;
    --secondary-color: #03dac6;
    --text-color: #ffffff;
    --text-muted: #b0b0b0;
    --border-radius: 16px;
    --btn-size: 80px;
}

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

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.container {
    background-color: var(--surface-color);
    padding: 40px;
    border-radius: 30px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
    width: 95%;
    max-width: 1000px;
    text-align: center;
    animation: fadeIn 0.5s ease-out;
    display: grid;
    grid-template-columns: 300px 1fr;
    grid-template-rows: auto 1fr;
    gap: 30px;
    align-items: start;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

header {
    grid-column: 1 / -1;
    margin-bottom: 10px;
}

header h1 {
    font-weight: 700;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 10px;
    letter-spacing: -1px;
}

header p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.controls-wrapper {
    background-color: var(--surface-light);
    padding: 20px;
    border-radius: var(--border-radius);
    display: flex;
    flex-direction: column;
    gap: 20px;
    text-align: left;
    height: 100%;
}

.control-group {
    display: flex;
    flex-direction: column;
}

.control-group label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 5px;
}

input[type="number"], select {
    background: var(--bg-color);
    border: 1px solid #444;
    color: var(--text-color);
    padding: 8px 12px;
    border-radius: 8px;
    font-family: inherit;
    font-size: 1rem;
    transition: border-color 0.2s;
    width: 100%;
}

input[type="number"]:focus, select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.ctrl-hint {
    font-size: 0.7rem;
    color: #666;
    margin-top: 4px;
}

.range-container {
    display: flex;
    align-items: center;
    gap: 10px;
}

input[type="range"] {
    appearance: none;
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    background: #444;
    border-radius: 5px;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    background: var(--secondary-color);
    border-radius: 50%;
    cursor: pointer;
    transition: transform 0.2s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

#duration-val {
    font-size: 0.85rem;
    color: var(--secondary-color);
    min-width: 45px;
    text-align: right;
}

.keypad {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    grid-template-rows: repeat(4, 1fr);
    gap: 15px;
    perspective: 1000px;
    height: 100%;
    align-content: stretch;
}

.sound-btn {
    background: linear-gradient(135deg, #3a3a3a, #2a2a2a);
    border: none;
    border-radius: 12px;
    color: var(--text-color);
    font-family: inherit;
    font-size: 1.5rem;
    font-weight: 500;
    height: var(--btn-size);
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0,0,0,0.3);
    transition: all 0.1s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.sound-btn .btn-freq {
    font-size: 0.6rem;
    color: var(--text-muted);
    margin-top: 4px;
    opacity: 0.7;
}

.sound-btn:active {
    transform: translateY(2px) scale(0.98);
    box-shadow: 0 1px 2px rgba(0,0,0,0.3);
    background: var(--primary-color);
    color: #000;
}

.sound-btn:active .btn-freq {
    color: rgba(0,0,0,0.6);
}

.sound-btn::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 5px;
    height: 5px;
    background: rgba(255, 255, 255, 0.5);
    opacity: 0;
    border-radius: 100%;
    transform: scale(1, 1) translate(-50%);
    transform-origin: 50% 50%;
}

@keyframes ripple {
    0% { transform: scale(0, 0); opacity: 1; }
    20% { transform: scale(25, 25); opacity: 1; }
    100% { opacity: 0; transform: scale(40, 40); }
}

.sound-btn:focus:not(:active)::after {
    animation: ripple 1s ease-out;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-color);
}
::-webkit-scrollbar-thumb {
    background: #444;
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: #555;
}