/* ============================================
   Bill Splitting Tool — Styles
   Theme: Neon Mint Dark
   Primary: #00D2D3, Accent: #FF6B6B, BG: #0A2025
   ============================================ */

:root {
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    --bg: #0A2025;
    --bg-card: #0F2E35;
    --bg-input: #0A2025;
    --bg-hover: #153A42;

    --border: rgba(0, 210, 211, 0.12);
    --border-hover: rgba(0, 210, 211, 0.28);
    --border-focus: #00D2D3;

    --text: #E0F7F8;
    --text-secondary: #7EC8C8;
    --text-muted: #3A7A7A;

    --primary: #00D2D3;
    --primary-glow: rgba(0, 210, 211, 0.2);
    --secondary: #54E3E4;
    --accent: #FF6B6B;
    --accent-glow: rgba(255, 107, 107, 0.15);
    --green: #00B894;

    --radius: 12px;
    --radius-sm: 8px;
    --shadow: 0 2px 16px rgba(0, 0, 0, 0.4);
    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: var(--font-sans);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

.app {
    max-width: 520px;
    margin: 0 auto;
    padding: 24px 16px 40px;
}

.header {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 24px;
}

.header-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius);
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    box-shadow: 0 0 20px var(--primary-glow);
}

.header-title {
    font-size: 1.3rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.header-sub {
    font-size: 0.82rem;
    color: var(--text-secondary);
}

.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    margin-bottom: 14px;
    box-shadow: var(--shadow);
    animation: fadeIn 0.3s ease-out;
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 14px;
}

.card-title {
    font-size: 0.88rem;
    font-weight: 600;
    margin-bottom: 14px;
}

.card-header .card-title {
    margin-bottom: 0;
}

/* Form */
.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.form-grid> :last-child {
    grid-column: span 2;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.form-label {
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
    font-weight: 600;
}

.form-input,
.form-select {
    padding: 10px 12px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: var(--font-sans);
    font-size: 0.88rem;
    transition: border-color var(--transition);
}

.form-input:focus,
.form-select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-glow);
}

.form-select option {
    background: var(--bg-card);
}

.small-input {
    width: 80px;
    text-align: center;
}

.input-with-prefix {
    display: flex;
    align-items: center;
}

.prefix {
    padding: 10px 8px 10px 12px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-right: none;
    border-radius: var(--radius-sm) 0 0 var(--radius-sm);
    color: var(--primary);
    font-weight: 600;
    font-size: 0.9rem;
}

.input-with-prefix .form-input {
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    flex: 1;
}

/* Stepper */
.stepper {
    display: flex;
    align-items: center;
}

.stepper-btn {
    width: 36px;
    height: 36px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    color: var(--primary);
    font-size: 1.2rem;
    font-weight: 700;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition);
}

.stepper-btn:first-child {
    border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}

.stepper-btn:last-child {
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.stepper-btn:hover {
    background: var(--primary-glow);
}

.stepper-input {
    width: 50px;
    text-align: center;
    border-radius: 0;
    border-left: none;
    border-right: none;
    -moz-appearance: textfield;
    appearance: textfield;
}

.stepper-input::-webkit-inner-spin-button {
    -webkit-appearance: none;
}

/* Tip Presets */
.tip-presets {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    margin-bottom: 12px;
}

.tip-btn {
    flex: 1;
    min-width: 54px;
    padding: 8px 4px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-family: var(--font-sans);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
}

.tip-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.tip-btn.active {
    background: var(--primary-glow);
    border-color: var(--primary);
    color: var(--primary);
}

.custom-tip-row {
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Extras */
.extras-row {
    display: flex;
    gap: 12px;
}

/* Split Mode */
.mode-toggle {
    display: flex;
    gap: 4px;
}

.mode-btn {
    padding: 5px 14px;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-family: var(--font-sans);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
}

.mode-btn.active {
    background: var(--primary-glow);
    border-color: var(--primary);
    color: var(--primary);
}

.hint {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-bottom: 10px;
}

.uneven-row {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 8px;
}

.uneven-name {
    font-size: 0.82rem;
    min-width: 72px;
}

.uneven-slider {
    flex: 1;
    accent-color: var(--primary);
}

.uneven-pct {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--primary);
    min-width: 40px;
    text-align: right;
}

.uneven-total {
    font-size: 0.78rem;
    font-weight: 600;
    text-align: right;
    margin-top: 6px;
}

.uneven-total.invalid {
    color: var(--accent);
}

/* Receipt */
.receipt {
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px;
    font-family: var(--font-mono);
}

.receipt-row {
    display: flex;
    justify-content: space-between;
    padding: 4px 0;
    font-size: 0.82rem;
    color: var(--text-secondary);
}

.receipt-row.total {
    font-size: 1rem;
    font-weight: 700;
    color: var(--primary);
}

.receipt-row.per-person {
    color: var(--secondary);
    font-weight: 600;
}

.receipt-divider {
    border-bottom: 1px dashed var(--border);
    margin: 8px 0;
}

.result-actions {
    display: flex;
    gap: 8px;
    margin-top: 14px;
}

.btn-action {
    flex: 1;
    padding: 10px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-family: var(--font-sans);
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    text-align: center;
}

.btn-action:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.btn-sm {
    padding: 4px 10px;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-muted);
    font-size: 0.72rem;
    cursor: pointer;
    transition: all var(--transition);
}

.btn-sm:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* History */
.history-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 12px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    margin-bottom: 6px;
    font-size: 0.78rem;
}

.history-amount {
    font-family: var(--font-mono);
    color: var(--primary);
    font-weight: 600;
}

.history-date {
    color: var(--text-muted);
    font-size: 0.7rem;
}

.footer {
    text-align: center;
    margin-top: 16px;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(80px);
    background: var(--bg-card);
    border: 1px solid var(--primary);
    border-radius: var(--radius-sm);
    padding: 10px 20px;
    font-size: 0.82rem;
    color: var(--primary);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
    opacity: 0;
    transition: transform 0.3s ease, opacity 0.3s ease;
    pointer-events: none;
    z-index: 100;
}

.toast.visible {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(8px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 520px) {
    .app {
        padding: 16px 10px 32px;
    }

    .form-grid {
        grid-template-columns: 1fr;
    }

    .form-grid> :last-child {
        grid-column: span 1;
    }
}