:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --border-color: #334155;
    --success-color: #10b981;
    /* System Font Stack for maximum performance and privacy */
    --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, 'Liberation Mono', monospace;
}

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

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

/* Security Disclaimer Banner */
.disclaimer-banner {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.15), rgba(239, 68, 68, 0.1));
    border-left: 4px solid #f59e0b;
    color: #fbbf24;
    font-size: 0.8rem;
    font-weight: 500;
    margin: 0;
}

.disclaimer-banner svg {
    flex-shrink: 0;
    color: #f59e0b;
}

.max-length {
    color: var(--text-secondary);
    font-size: 0.7rem;
    margin-left: 8px;
}

.app-container {
    width: 100%;
    max-width: 1000px;
    background-color: var(--card-bg);
    border-radius: 16px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: rgba(30, 41, 59, 0.8);
    backdrop-filter: blur(10px);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--accent-color);
}

.logo h1 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.icon-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    border-radius: 8px;
    transition: all 0.2s;
}

.icon-btn:hover {
    background-color: var(--border-color);
    color: var(--text-primary);
}

main {
    padding: 24px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 24px;
}

@media (min-width: 768px) {
    main {
        grid-template-columns: 1fr auto 1fr;
        align-items: start;
    }
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

h2 {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.editor-container {
    height: 400px;
    background-color: rgba(15, 23, 42, 0.5);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    transition: border-color 0.2s;
}

.editor-container:focus-within {
    border-color: var(--accent-color);
}

textarea {
    width: 100%;
    height: 100%;
    background: transparent;
    border: none;
    padding: 16px;
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.5;
    resize: none;
    outline: none;
}

.stats {
    margin-top: 8px;
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-align: right;
}

.controls-section {
    display: flex;
    flex-direction: column;
    gap: 24px;
    padding: 24px 0;
    align-items: center;
    justify-content: center;
}

.decoder-selector {
    width: 100%;
}

.decoder-selector label {
    display: block;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

select {
    width: 100%;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 10px;
    border-radius: 8px;
    font-family: var(--font-sans);
    font-size: 0.875rem;
    outline: none;
    cursor: pointer;
}

select:focus {
    border-color: var(--accent-color);
}

.action-buttons {
    display: flex;
    flex-direction: column;
    /* Stack on mobile */
    gap: 12px;
    width: 100%;
}

button {
    padding: 12px 24px;
    border-radius: 8px;
    font-weight: 500;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
}

.primary-btn {
    background-color: var(--accent-color);
    color: white;
}

.primary-btn:hover {
    background-color: var(--accent-hover);
}

.secondary-btn {
    background-color: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.secondary-btn:hover {
    background-color: var(--border-color);
}

.copy-btn {
    padding: 4px 10px;
    font-size: 0.75rem;
    background-color: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
}

.copy-btn:hover {
    border-color: var(--text-secondary);
    color: var(--text-primary);
}

footer {
    padding: 16px 24px;
    border-top: 1px solid var(--border-color);
    background-color: rgba(15, 23, 42, 0.3);
}

.security-note {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 0.75rem;
    color: var(--success-color);
}

/* Checkbox Style */
.checkbox-container {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-secondary);
    user-select: none;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    height: 18px;
    width: 18px;
    background-color: transparent;
    border: 2px solid var(--text-secondary);
    border-radius: 4px;
    position: relative;
    transition: all 0.2s;
}

.checkbox-container:hover input~.checkmark {
    border-color: var(--accent-color);
}

.checkbox-container input:checked~.checkmark {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-container input:checked~.checkmark:after {
    display: block;
}

.checkbox-container .checkmark:after {
    left: 5px;
    top: 1px;
    width: 4px;
    height: 9px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.aux-inputs {
    width: 100%;
    margin-top: -12px;
    margin-bottom: 12px;
    display: flex;
    gap: 12px;
}

.aux-inputs.hidden {
    display: none;
}

.input-group {
    display: none;
    /* Hidden by default, toggled by JS */
    flex: 1;
}

.input-group.visible {
    display: block;
}

.input-group label {
    display: block;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.input-group input {
    width: 100%;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 10px;
    border-radius: 8px;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    outline: none;
}

.input-group input:focus {
    border-color: var(--accent-color);
}

/* Detected Encoding Badge */
.detected-badge {
    display: inline-block;
    padding: 4px 10px;
    background: linear-gradient(135deg, var(--accent-color), #6366f1);
    color: #fff;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 12px;
    margin-left: 10px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.detected-badge:empty {
    display: none;
}