:root {
    /* Ocean Blue Theme */
    --bg-dark: #0D1B2A;
    --bg-panel: #1B263B;
    --bg-input: #09131F;
    --bg-hover: rgba(116, 185, 255, 0.1);

    --border: #415A77;
    --border-highlight: #74B9FF;

    --primary: #0984E3;
    --primary-hover: #076CBA;
    --secondary: #74B9FF;
    --accent: #E17055;

    --text-main: #E0E1E6;
    --text-muted: #778DA9;
    --text-mono: #A8D0E6;

    --card-bg: rgba(27, 38, 59, 0.7);
    --glass-border: rgba(116, 185, 255, 0.2);

    --radius: 12px;
    --radius-sm: 8px;
    --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

.theme-light {
    --bg-dark: #F0F4F8;
    --bg-panel: #FFFFFF;
    --bg-input: #E2E8F0;
    --bg-hover: rgba(9, 132, 227, 0.1);

    --border: #CBD5E1;
    --border-highlight: #0984E3;

    --primary: #0984E3;
    --primary-hover: #076CBA;
    --secondary: #74B9FF;
    --accent: #E17055;

    --text-main: #1E293B;
    --text-muted: #64748B;
    --text-mono: #0369A1;

    --card-bg: #F8FAFC;
    --glass-border: rgba(9, 132, 227, 0.2);
}

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

body {
    font-family: 'Inter', system-ui, sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    min-height: 100vh;
    transition: background-color var(--transition), color var(--transition);
}

.hidden {
    display: none !important;
}

/* Layout */
.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    height: 100vh;
}

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--primary);
}

.logo h1 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-main);
    letter-spacing: -0.02em;
}

.icon-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    padding: 0.5rem;
    border-radius: 50%;
    cursor: pointer;
    transition: all var(--transition);
}

.icon-btn:hover {
    background: var(--bg-panel);
    color: var(--text-main);
}

/* Main Content Grid */
.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    flex: 1;
    min-height: 0;
    /* Important for scrollable areas inside */
}

/* Panels */
.panel {
    background: var(--bg-panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    display: flex;
    flex-direction: column;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

.panel-header {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border);
    background: rgba(0, 0, 0, 0.1);
}

.panel-header h2 {
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.02em;
}

.panel-body {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    overflow-y: auto;
}

/* Forms */
.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-row {
    display: flex;
    gap: 1rem;
}

.flex-1 {
    flex: 1;
}

label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

input[type="text"],
textarea,
select {
    background: var(--bg-input);
    border: 1px solid var(--border);
    color: var(--text-main);
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    font-family: 'Inter', sans-serif;
    font-size: 0.95rem;
    outline: none;
    transition: border-color var(--transition);
}

input:focus,
textarea:focus,
select:focus {
    border-color: var(--primary);
}

.monospaced-input {
    font-family: 'JetBrains Mono', monospace !important;
    font-size: 0.9rem !important;
}

textarea {
    resize: vertical;
    min-height: 120px;
    line-height: 1.5;
}

.input-with-prefix {
    display: flex;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
    transition: border-color var(--transition);
}

.input-with-prefix:focus-within {
    border-color: var(--primary);
}

.input-with-prefix span {
    padding: 0.75rem;
    background: rgba(0, 0, 0, 0.1);
    color: var(--text-muted);
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
    border-right: 1px solid var(--border);
}

.input-with-prefix input {
    border: none;
    border-radius: 0;
    flex: 1;
}

.input-with-prefix input:focus {
    border: none;
}

/* Radio Pill Selector */
.radio-group {
    display: flex;
    background: var(--bg-input);
    border-radius: var(--radius-sm);
    padding: 0.25rem;
    position: relative;
    border: 1px solid var(--border);
}

.radio-btn {
    flex: 1;
    text-align: center;
    padding: 0.5rem;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-muted);
    z-index: 1;
    transition: color 0.3s;
}

.radio-btn input {
    display: none;
}

.radio-btn.active {
    color: var(--text-main);
    font-weight: 600;
}

.pill-slider {
    position: absolute;
    top: 0.25rem;
    bottom: 0.25rem;
    left: 0.25rem;
    width: calc((100% - 0.5rem) / 3);
    /* 3 options */
    background: var(--bg-panel);
    border-radius: 4px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    z-index: 0;
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.input-stats {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-align: right;
}

/* Advanced Params Accordion */
.advanced-params {
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: rgba(0, 0, 0, 0.05);
}

.advanced-header {
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    user-select: none;
}

.advanced-header h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-main);
}

.advanced-header .chevron {
    transition: transform 0.3s;
    color: var(--text-muted);
}

.advanced-header.open .chevron {
    transform: rotate(180deg);
}

.advanced-body {
    display: none;
    padding: 0 1rem 1rem 1rem;
}

.advanced-body.expanded {
    display: block;
}

.param-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

/* Custom Checkbox */
.checkbox-group {
    justify-content: center;
    gap: 0.75rem;
}

.custom-checkbox {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-size: 0.85rem;
    color: var(--text-main);
    font-weight: 500;
    text-transform: none;
    letter-spacing: 0;
}

.custom-checkbox input {
    display: none;
}

.checkmark {
    width: 18px;
    height: 18px;
    border: 1px solid var(--border);
    border-radius: 4px;
    background: var(--bg-input);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

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

.custom-checkbox input:checked~.checkmark::after {
    content: '';
    width: 4px;
    height: 8px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
    margin-top: -2px;
}

/* Buttons */
.btn {
    padding: 0.85rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-family: 'Inter', sans-serif;
    cursor: pointer;
    border: none;
    transition: all var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 1rem;
}

.btn.primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
}

.btn.primary:hover {
    box-shadow: 0 10px 20px rgba(9, 132, 227, 0.3);
    transform: translateY(-2px);
}

.btn.primary:active {
    transform: translateY(0);
}

.full-width {
    width: 100%;
}

/* --- Results Panel --- */
.result-body {
    gap: 2rem;
}

.result-card {
    background: var(--bg-input);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.primary-result {
    background: radial-gradient(circle at top right, rgba(9, 132, 227, 0.15), transparent 70%), var(--bg-panel);
    border-color: var(--primary);
}

.result-label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
}

.result-value-container {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.result-value {
    flex: 1;
    font-family: 'JetBrains Mono', monospace;
    color: var(--text-mono);
    word-break: break-all;
}

.primary-result .result-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
}

.primary-result .prefix {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-muted);
    font-family: 'JetBrains Mono', monospace;
}

.dec-val {
    font-size: 1.25rem;
    font-weight: 600;
}

.bin-val {
    font-size: 1rem;
    letter-spacing: 1px;
    color: var(--accent);
}

.copy-btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-muted);
    border-radius: 6px;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s;
    flex-shrink: 0;
}

.copy-btn:hover {
    background: var(--bg-hover);
    color: var(--primary);
    border-color: var(--primary);
}

.divider {
    height: 1px;
    background: var(--border);
    width: 100%;
    border-radius: 1px;
}

.calculation-steps h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 1rem;
}

.step-log {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
}

.log-entry {
    display: flex;
    justify-content: space-between;
    border-bottom: 1px dashed var(--border);
    padding-bottom: 0.25rem;
}

.log-label {
    color: var(--text-muted);
}

.log-val {
    color: var(--text-mono);
}


/* Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-main);
    color: var(--bg-dark);
    padding: 0.75rem 1.5rem;
    border-radius: 99px;
    font-weight: 600;
    font-size: 0.9rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
    z-index: 1000;
    transition: opacity 0.3s, transform 0.3s;
}

.toast.hidden {
    opacity: 0;
    transform: translateX(-50%) translateY(20px);
    pointer-events: none;
}

/* Responsive */
@media (max-width: 900px) {
    .app-container {
        height: auto;
        padding: 1rem;
    }

    .main-content {
        grid-template-columns: 1fr;
    }

    .panel-body {
        overflow: visible;
    }
}

@media (max-width: 600px) {
    .param-grid {
        grid-template-columns: 1fr;
    }
}