/* =============================================
   Curtain Simulator — Styles
   Internal Tool — Light/Dark Theme
   ============================================= */

/* --- Light Theme (default) --- */
:root,
[data-theme="light"] {
    --bg: #f4f5f7;
    --bg-card: #ffffff;
    --bg-input: #f0f1f3;
    --bg-input-focus: #e8e9ec;
    --bg-hover: #f8f8fa;
    --bg-toggle: #e9eaed;
    --bg-active: #4f46e5;
    --bg-active-light: rgba(79, 70, 229, 0.08);

    --text: #1a1a2e;
    --text-secondary: #5a5a72;
    --text-muted: #8e8ea0;
    --text-on-active: #ffffff;

    --border: #e2e3e8;
    --border-focus: #4f46e5;

    --success: #059669;
    --success-bg: #ecfdf5;
    --success-border: #a7f3d0;
    --warning: #d97706;
    --error: #dc2626;

    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.1);

    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-full: 100px;

    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* --- Dark Theme --- */
[data-theme="dark"] {
    --bg: #0f0f14;
    --bg-card: #1a1a24;
    --bg-input: rgba(255,255,255,0.06);
    --bg-input-focus: rgba(255,255,255,0.1);
    --bg-hover: rgba(255,255,255,0.04);
    --bg-toggle: rgba(255,255,255,0.08);
    --bg-active: #6d5ced;
    --bg-active-light: rgba(109, 92, 237, 0.12);

    --text: #e8e8f0;
    --text-secondary: #9494a8;
    --text-muted: #5c5c72;
    --text-on-active: #ffffff;

    --border: rgba(255,255,255,0.08);
    --border-focus: #6d5ced;

    --success: #34d399;
    --success-bg: rgba(52, 211, 153, 0.1);
    --success-border: rgba(52, 211, 153, 0.25);
    --warning: #fbbf24;
    --error: #ef4444;

    --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.4);
}

/* --- Reset --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    transition: background 0.3s ease, color 0.3s ease;
}

/* --- App Shell --- */
.app {
    max-width: 680px;
    margin: 0 auto;
    padding: 0 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* --- Top Bar --- */
.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 1.5rem;
}

.topbar-left {
    display: flex;
    align-items: center;
    gap: 0.6rem;
}

.topbar-icon {
    width: 30px;
    height: 30px;
    border-radius: var(--radius-sm);
}

.topbar-title {
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.topbar-right {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* --- Theme Toggle --- */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.theme-toggle:hover {
    border-color: var(--border-focus);
    color: var(--text);
    background: var(--bg-hover);
}

/* Show sun in dark mode, moon in light mode */
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }
[data-theme="dark"] .icon-sun { display: block; }
[data-theme="dark"] .icon-moon { display: none; }

/* --- Install Button --- */
.install-btn {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    padding: 7px 14px;
    background: var(--bg-active);
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-on-active);
    font-family: var(--font);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.install-btn:hover {
    opacity: 0.9;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.install-btn.hidden {
    display: none;
}

/* --- Main --- */
.main {
    flex: 1;
}

/* --- Calculator --- */
.calculator {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: background 0.3s ease, border-color 0.3s ease;
}

/* --- Rows --- */
.calc-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

.calc-row-top {
    grid-template-columns: 1fr 1fr;
}

/* --- Field Group --- */
.field-group {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.field-group.hidden {
    display: none;
}

.field-label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

/* --- Toggle Group --- */
.toggle-group {
    display: flex;
    gap: 0;
    background: var(--bg-toggle);
    padding: 3px;
    border-radius: var(--radius-sm);
}

.toggle-btn {
    flex: 1;
    padding: 8px 12px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-family: var(--font);
    font-size: 0.82rem;
    font-weight: 600;
    border-radius: calc(var(--radius-sm) - 2px);
    cursor: pointer;
    transition: all 0.2s ease;
}

.toggle-btn:hover {
    color: var(--text-secondary);
}

.toggle-btn.active {
    background: var(--bg-active);
    color: var(--text-on-active);
    box-shadow: var(--shadow-sm);
}

/* --- Input Fields --- */
.input-wrap {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrap input {
    width: 100%;
    padding: 10px 36px 10px 12px;
    background: var(--bg-input);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: var(--font);
    font-size: 0.95rem;
    font-weight: 500;
    outline: none;
    transition: all 0.2s ease;
}

.input-wrap input::placeholder {
    color: var(--text-muted);
}

.input-wrap input:focus {
    border-color: var(--border-focus);
    background: var(--bg-input-focus);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.12);
}

.input-unit {
    position: absolute;
    right: 12px;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    pointer-events: none;
}

.input-wrap.error input {
    border-color: var(--error);
    box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.1);
}

/* --- Width as Height Row --- */
.wah-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1rem;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    margin-bottom: 1.25rem;
}

.wah-row.hidden {
    display: none;
}

.wah-text {
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--text);
}

.wah-hint {
    color: var(--text-muted);
    font-weight: 400;
}

/* --- Switch --- */
.switch {
    position: relative;
    width: 44px;
    height: 24px;
    flex-shrink: 0;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    inset: 0;
    background: var(--bg-toggle);
    border-radius: var(--radius-full);
    transition: all 0.25s ease;
}

.slider::before {
    content: "";
    position: absolute;
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background: white;
    border-radius: 50%;
    transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.switch input:checked + .slider {
    background: var(--bg-active);
}

.switch input:checked + .slider::before {
    transform: translateX(20px);
}

/* --- Calculate Button --- */
.calc-btn {
    width: 100%;
    padding: 12px;
    background: var(--bg-active);
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-on-active);
    font-family: var(--font);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-bottom: 1rem;
}

.calc-btn:hover {
    opacity: 0.92;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

/* --- Result --- */
.result {
    background: var(--success-bg);
    border: 1px solid var(--success-border);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    animation: slideIn 0.35s ease;
}

.result.hidden {
    display: none;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.result-top {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.6rem;
}

.result-badge {
    font-size: 0.68rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    padding: 2px 8px;
    background: var(--success);
    color: white;
    border-radius: var(--radius-full);
}

.result-method {
    font-size: 0.72rem;
    color: var(--text-muted);
    font-weight: 500;
}

.result-value-row {
    display: flex;
    align-items: baseline;
    gap: 0.4rem;
    margin-bottom: 0.75rem;
}

.result-number {
    font-size: 2.4rem;
    font-weight: 800;
    color: var(--success);
    line-height: 1;
    letter-spacing: -0.03em;
}

.result-unit {
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.result-breakdown {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border);
}

.bd-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
}

.bd-label {
    color: var(--text-secondary);
}

.bd-value {
    font-weight: 600;
    color: var(--text);
    font-variant-numeric: tabular-nums;
}

.bd-highlight {
    color: var(--success);
    font-weight: 700;
}

.bd-warn {
    color: var(--warning);
}

/* --- Accessories Section --- */
.accessories-section {
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1.5px dashed var(--border);
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.accessories-title {
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--bg-active);
    margin-bottom: 0.15rem;
}

.bd-hint {
    font-weight: 400;
    color: var(--text-muted);
    font-size: 0.72rem;
}

.bd-accent {
    color: var(--bg-active);
    font-weight: 700;
}

/* --- Formula Reference --- */
.reference {
    margin-top: 1.5rem;
    margin-bottom: 2rem;
}

.reference-toggle {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.75rem 1rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    list-style: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s ease;
}

.reference-toggle:hover {
    color: var(--text);
    border-color: var(--border-focus);
}

.reference-toggle::before {
    content: "▶";
    font-size: 0.6rem;
    transition: transform 0.2s ease;
}

details[open] .reference-toggle::before {
    transform: rotate(90deg);
}

.reference-toggle::-webkit-details-marker {
    display: none;
}

.reference-content {
    padding: 1rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-top: none;
    border-radius: 0 0 var(--radius-sm) var(--radius-sm);
}

.formula-row {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border);
}

.formula-row:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.formula-row h3 {
    font-size: 0.82rem;
    font-weight: 600;
    margin-bottom: 0.3rem;
}

.formula-row code {
    display: block;
    font-family: 'JetBrains Mono', 'Fira Code', monospace;
    font-size: 0.75rem;
    color: var(--bg-active);
    background: var(--bg-input);
    padding: 6px 10px;
    border-radius: 4px;
    margin-bottom: 0.3rem;
    overflow-x: auto;
}

.formula-row p {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* --- Shake Animation --- */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20% { transform: translateX(-5px); }
    40% { transform: translateX(5px); }
    60% { transform: translateX(-3px); }
    80% { transform: translateX(3px); }
}

/* --- Responsive --- */
@media (max-width: 600px) {
    .app {
        padding: 0 0.75rem;
    }

    .calculator {
        padding: 1.25rem;
    }

    .calc-row {
        grid-template-columns: 1fr 1fr;
    }

    .calc-row-top {
        grid-template-columns: 1fr 1fr;
    }

    .result-number {
        font-size: 2rem;
    }

    .bd-row {
        flex-direction: column;
        align-items: flex-start;
        gap: 1px;
    }

    .wah-row {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.6rem;
    }
}

@media (max-width: 420px) {
    .calc-row {
        grid-template-columns: 1fr;
    }

    .topbar-title {
        font-size: 0.88rem;
    }
}