/* --- Futuristic & Clean Theme --- */
  :root {
    /* Dark theme (default) */
    --bg-color: #050505;
    --surface-color: #101010;
    --text-color: #f5f5f5d7;
    --text-color-strong: #f5f5f5;
    --subtle-text-color: #727272;
    --accent-color: #00BFFF;
    --hover-bg-color: rgba(255, 255, 255, 0.05);
    --border-color: rgba(255, 255, 255, 0.1);
    --backdrop-bg: rgba(16, 16, 16, 0.5);
    --box-shadow: none;
    --app-background: linear-gradient(190deg,#131313 0%, #0d0d0d 70%, #030303 100%);


body[data-theme="light"] {
    /* Light theme */
    /* --bg-color: #f5f5f5;
    --surface-color: #ffffff;
    --text-color: #505050; */
    --bg-color: #d5d5d5;
    --surface-color: #bbb;
    --text-color: #535353;
    --text-color-strong: #050505;
    /* --subtle-text-color: #868686; */
    --subtle-text-color: #484848;
    --accent-color: #007BFF;
    --hover-bg-color: rgba(0, 0, 0, 0.05);
    --border-color: rgba(0, 0, 0, 0.1);
    --backdrop-bg: rgba(255, 255, 255, 0.5);
    --box-shadow: inset 3px -7px 8px 2px #00000040, -3px 7px 10px 4px #00000040;
    --app-background: linear-gradient(210deg,rgb(255, 255, 255) 0%, rgba(191, 191, 191, 0.65) 88%, rgba(198, 198, 198, 0.69) 100%);

}

/* --- Reset and Base --- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Inter', sans-serif;
    font-weight: 200;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 2rem 1rem;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* --- Main Container --- */
.app-container {
    width: 100%;
    max-width: 480px;
    background: var(--app-background);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    overflow: hidden;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    /* background-color: var(--backdrop-bg); */
    transition: border-color 0.3s ease, background-color 0.3s ease;
    box-shadow: var(--box-shadow);

}

.app-content {
    padding: 2.5rem;
}

/* --- Header --- */
.header {
    text-align: center;
    margin-bottom: 3rem;
}

.header-icon {
    stroke: var(--text-color-strong);
    stroke-width: 1;
    margin-bottom: 0.75rem;
    transition: stroke 0.3s ease;
}

.header-title {
    font-size: 2.5rem;
    font-weight: 300;
    color: var(--text-color-strong);
    letter-spacing: 4px;
    text-transform: uppercase;
    transition: color 0.3s ease;
}

.header-subtitle {
    font-size: 0.9rem;
    color: var(--subtle-text-color);
    font-weight: 200;
    letter-spacing: 2px;
}

/* --- Password Display --- */
.password-display-wrapper {
    position: relative;
    margin-bottom: 0.5rem;
}

#password-display {
    width: 100%;
    background-color: var(--bg-color);
    border: 1px solid transparent;
    color: var(--text-color);
    font-family: 'Menlo', 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    padding: 1.5rem;
    border-radius: 8px;
    resize: none;
    min-height: 150px;
    text-align: center;
    transition: border-color 0.3s ease, box-shadow 0.3s ease, background-color 0.3s ease, color 0.3s ease;
}

#password-display:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 15px rgba(0, 191, 255, 0.2);
}

#copy-button {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--subtle-text-color);
    padding: 0.5rem;
    border-radius: 50%;
    transition: color 0.3s ease, background-color 0.3s ease;
}

#copy-button:hover {
    color: var(--text-color-strong);
    background-color: var(--hover-bg-color);
}

#copy-feedback {
    text-align: center;
    height: 20px;
    font-size: 0.8rem;
    color: var(--accent-color);
    opacity: 0;
    transition: opacity 0.5s ease;
    letter-spacing: 1px;
}

#copy-feedback.fade-in-out {
    opacity: 1;
}

/* --- Options Section --- */
.options-section {
    margin-top: 2.5rem;
}

.options-legend {
    text-align: center;
    font-size: 0.8rem;
    color: var(--subtle-text-color);
    margin-bottom: 1.5rem;
    font-weight: 300;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.radio-group {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.5rem;
    transition: border-color 0.3s ease;
}

.radio-label {
    flex: 1;
    padding: 0.75rem;
    text-align: center;
    cursor: pointer;
    border-radius: 6px;
    transition: background-color 0.3s ease, color 0.3s ease;
    color: var(--subtle-text-color);
}

.radio-label-title {
    display: block;
    font-size: 0.9rem;
    color: var(--text-color);
    transition: color 0.3s ease;
    font-weight: 100 !important;
    text-transform: lowercase;
}

.radio-label-desc { display: none; }
input[type="radio"] { display: none; }

input[type="radio"]:checked + .radio-label .radio-label-title {
      color: var(--text-color-strong);
      font-weight: 700 !important;
      text-transform: uppercase;
}

/* --- Advanced Options --- */
.advanced-options {
    margin-top: 2.5rem;
    display: grid;
    grid-template-columns: 1fr 80px;
    gap: 1.5rem;
    align-items: center;
}

.option-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    color: var(--subtle-text-color);
}

#length-value {
    font-weight: 300;
    color: var(--text-color-strong);
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 2px;
    background: var(--border-color);
    border-radius: 2px;
    outline: none;
    transition: background 0.3s;
}
input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    background: var(--text-color-strong);
    cursor: pointer;
    border-radius: 50%;
    transition: transform 0.2s ease, box-shadow 0.3s ease, background-color 0.3s ease;
}
input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.1); }
input[type="range"]::-webkit-slider-thumb:active {
    box-shadow: 0 0 10px var(--accent-color);
    background: var(--accent-color);
}

#quantity-input {
    width: 100%;
    background-color: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color-strong);
    padding: 0.5rem;
    border-radius: 8px;
    text-align: center;
    font-size: 1rem;
    font-weight: 300;
    transition: border-color 0.3s ease, box-shadow 0.3s ease, color 0.3s ease;
}
#quantity-input:focus {
    outline: none;
    border-color: var(--accent-color);
}

/* --- Action Buttons --- */
.action-button {
    width: 100%;
    background-color: transparent;
    border: none;
    color: var(--text-color);
    padding: 1rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 300;
    cursor: pointer;
    transition: background-color 0.3s ease, color 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.action-button:hover {
    background-color: var(--hover-bg-color);
    color: var(--text-color-strong);
}

#generate-button { margin-top: 3rem; }

/* --- Footer --- */
.footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2.5rem;
    font-size: 0.8rem;
    color: var(--subtle-text-color);
    font-weight: 200;
    letter-spacing: 2px;
    text-transform: uppercase;
}

#theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--subtle-text-color);
    padding: 0.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.3s ease, background-color 0.3s ease;
}
#theme-toggle:hover {
    color: var(--text-color-strong);
    background-color: var(--hover-bg-color);
}
.icon-sun, .icon-moon { transition: transform 0.3s ease-out; }
body[data-theme="light"] .icon-moon { display: none; }
body[data-theme="dark"] .icon-sun { display: none; }

/* --- Loader --- */
.loader {
    width: 16px;
    height: 16px;
    border: 2px solid currentColor;
    border-bottom-color: transparent;
    border-radius: 50%;
    display: inline-block;
    box-sizing: border-box;
    animation: rotation 1s linear infinite;
}
.hidden { display: none; }
@keyframes rotation {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* --- Responsive --- */
@media (max-width: 600px) {
    html { font-size: 14px; }
    body { padding: 1rem 0.5rem; }
    .app-content, .footer { padding: 1.5rem; }
    .header-title { font-size: 2rem; }
    .advanced-options {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
}