:root {
    --bg-main: #111;
    --bg-canvas: #1a1a1a;
    --text-main: #eee;
    --text-dim: #ccc;
    --ui-bg: #333;
    --ui-bg-hover: #444;
    --ui-border: #555;
    --ui-accent-bg: #eee;
    --ui-accent-text: #111;
    --ui-bg-range-hover: #555;
    --ui-accent-bg-hover: #fff;
    --select-arrow: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23eee' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
}

body.light-mode {
    --bg-main: #f4f4f4;
    --bg-canvas: #ffffff;
    --text-main: #222;
    --text-dim: #555;
    --ui-bg: #e0e0e0;
    --ui-bg-hover: #d0d0d0;
    --ui-border: #bbb;
    --ui-accent-bg: #222;
    --ui-accent-text: #eee;
    --ui-bg-range-hover: #c0c0c0;
    --ui-accent-bg-hover: #333;
    --select-arrow: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23222' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
}

body {
    background-color: var(--bg-main);
    color: var(--text-main);
    font-family: 'Noto Sans', sans-serif;
    text-align: center;
    margin: 0;
    overflow: hidden;
    height: 100vh;
}

body.app-active {
    display: flex;
    flex-direction: column;
}

#menu-container {
    flex-shrink: 0;
    padding: 15px 15px 0;
    display: none;
}
body.app-active #menu-container {
    display: block;
}

#menu-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#menu-header h1 {
    margin: 0;
    font-weight: 300;
    flex-shrink: 0;
}

#toggle-menu-btn {
    padding: 8px 15px;
    font-size: 14px;
    cursor: pointer;
    background-color: var(--ui-bg);
    color: var(--text-main);
    border: 1px solid var(--ui-border);
    border-radius: 5px;
    margin: 0;
    transition: background-color 0.2s;
}

#toggle-menu-btn:hover {
     background-color: var(--ui-bg-hover);
}

#menu-content {
    max-height: 500px; /* generous height */
    overflow: hidden;
    transition: max-height 0.4s ease-in-out, padding-top 0.4s ease-in-out;
    padding-top: 10px;
}

#menu-content.hidden {
    max-height: 0;
    padding-top: 0;
}

/* For hiding the menu title */
#menu-title {
    max-height: 100px; /* generous height for animation */
    opacity: 1;
    transition: max-height 0.4s ease-in-out, opacity 0.3s ease-in-out;
    overflow: hidden;
}

#menu-title.hidden {
    max-height: 0;
    opacity: 0;
}

h1 {
    margin: 0;
    font-weight: 300;
    flex-shrink: 0;
}

#controls {
    margin-bottom: 10px;
    flex-shrink: 0;
}

#sliders {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 15px;
    flex-shrink: 0;
    flex-wrap: wrap;
    padding: 0 15px;
}

#shape-controls,
#view-controls,
#movement-controls,
#theme-controls {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 15px;
    flex-shrink: 0;
}

#view-controls {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 15px;
    flex-shrink: 0;
}

.shape-btn {
    padding: 8px 15px;
    font-size: 14px;
    cursor: pointer;
    background-color: var(--ui-bg);
    color: var(--text-main);
    border: 1px solid var(--ui-border);
    border-radius: 5px;
    transition: background-color 0.2s, border-color 0.2s;
}

.shape-btn:hover {
    background-color: var(--ui-bg-hover);
}

.shape-btn.active {
    background-color: var(--ui-accent-bg);
    color: var(--ui-accent-text);
    border-color: var(--ui-accent-bg);
}

.view-btn {
    padding: 8px 15px;
    font-size: 14px;
    cursor: pointer;
    background-color: var(--ui-bg);
    color: var(--text-main);
    border: 1px solid var(--ui-border);
    border-radius: 5px;
    transition: background-color 0.2s, border-color 0.2s;
}

.view-btn:hover {
    background-color: var(--ui-bg-hover);
}

.view-btn.active {
    background-color: var(--ui-accent-bg);
    color: var(--ui-accent-text);
    border-color: var(--ui-accent-bg);
}

.movement-btn {
    padding: 8px 15px;
    font-size: 14px;
    cursor: pointer;
    background-color: var(--ui-bg);
    color: var(--text-main);
    border: 1px solid var(--ui-border);
    border-radius: 5px;
    transition: background-color 0.2s, border-color 0.2s;
}

.movement-btn:hover {
    background-color: var(--ui-bg-hover);
}

.movement-btn.active {
    background-color: var(--ui-accent-bg);
    color: var(--ui-accent-text);
    border-color: var(--ui-accent-bg);
}

.slider-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    color: var(--text-dim);
    font-size: 14px;
}

.slider-container label {
    margin-bottom: 8px;
    font-weight: 300;
}

select {
    padding: 8px 10px;
    font-size: 14px;
    background-color: var(--ui-bg);
    color: var(--text-main);
    border: 1px solid var(--ui-border);
    border-radius: 5px;
    -webkit-appearance: none;
    appearance: none;
    cursor: pointer;
    min-width: 120px;
    background-image: var(--select-arrow);
    background-repeat: no-repeat;
    background-position: right 10px center;
    background-size: 1em;
}

select:hover {
    background-color: var(--ui-bg-hover);
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 200px;
    height: 8px;
    background: var(--ui-bg-hover);
    border-radius: 5px;
    outline: none;
    transition: background-color 0.2s;
}

input[type="range"]:hover {
    background: var(--ui-bg-range-hover);
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    background: var(--ui-accent-bg);
    cursor: pointer;
    border-radius: 50%;
    border: 2px solid var(--ui-border);
    transition: background-color 0.2s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    background: var(--ui-accent-bg-hover);
}

input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: var(--ui-accent-bg);
    cursor: pointer;
    border-radius: 50%;
    border: 2px solid var(--ui-border);
    transition: background-color 0.2s;
}

input[type="range"]::-moz-range-thumb:hover {
    background: var(--ui-accent-bg-hover);
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    background-color: var(--ui-bg);
    color: var(--text-main);
    border: 1px solid var(--ui-border);
    border-radius: 5px;
    margin: 0 5px;
    transition: background-color 0.2s;
}

button:hover {
    background-color: var(--ui-bg-hover);
}

#canvas-container {
    position: relative;
    flex-grow: 1;
    width: 100%;
    background-color: var(--bg-canvas);
    display: none;
}
body.app-active #canvas-container {
    display: block;
}

#canvas-container > canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100% !important;
    height: 100% !important;
}

#pendulum-canvas {
    background-color: var(--bg-canvas);
    display: block;
    width: 100%;
    height: 100%;
}

#title-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-main);
    color: var(--text-main);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    flex-direction: column;
    text-align: center;
    transition: opacity 0.5s ease-out, visibility 0s 0.5s;
    visibility: visible;
    opacity: 1;
}

#title-screen.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

#title-content h1 {
    font-size: 3.5rem;
    font-weight: 200;
    margin-bottom: 0.5rem;
    letter-spacing: 2px;
}

#title-content p {
    font-size: 1.2rem;
    font-weight: 300;
    color: var(--text-dim);
    margin-bottom: 2rem;
}

#enter-btn {
    padding: 15px 40px;
    font-size: 1.2rem;
    cursor: pointer;
    background-color: var(--ui-accent-bg);
    color: var(--ui-accent-text);
    border: none;
    border-radius: 8px;
    transition: background-color 0.2s, transform 0.2s;
    font-weight: 500;
}

#enter-btn:hover {
    background-color: var(--ui-accent-bg-hover);
    transform: scale(1.05);
}