/* ============================================
   TOOLS — Calculators & Converters
   Design System aligned with Portfolio
   Dark-first · Glassmorphism · Modern
   ============================================ */

/* ---------- Custom Properties ---------- */
:root {
    --font-heading: 'Space Grotesk', sans-serif;
    --font-body: 'Inter', sans-serif;

    --hue: 220;
    --accent-hue: 217;

    --bg-primary: hsl(var(--hue), 20%, 4%);
    --bg-secondary: hsl(var(--hue), 20%, 7%);
    --bg-card: hsla(var(--hue), 20%, 10%, 0.6);
    --bg-card-hover: hsla(var(--hue), 20%, 14%, 0.8);
    --bg-elevated: hsl(var(--hue), 20%, 12%);
    --bg-input: hsl(var(--hue), 20%, 8%);
    --bg-nav: hsla(var(--hue), 20%, 4%, 0.8);
    --bg-nav-mobile: hsla(var(--hue), 20%, 4%, 0.95);
    --nav-hover: hsla(var(--hue), 10%, 100%, 0.05);

    --text-primary: hsl(var(--hue), 10%, 96%);
    --text-secondary: hsl(var(--hue), 10%, 65%);
    --text-tertiary: hsl(var(--hue), 10%, 55%);

    --accent: hsl(var(--accent-hue), 91%, 60%);
    --accent-dim: hsl(var(--accent-hue), 91%, 50%);
    --accent-glow: hsla(var(--accent-hue), 91%, 60%, 0.3);
    --accent-subtle: hsla(var(--accent-hue), 91%, 60%, 0.08);

    --success: hsl(142, 71%, 45%);
    --danger: hsl(0, 70%, 55%);

    --border: hsla(var(--hue), 10%, 100%, 0.08);
    --border-hover: hsla(var(--hue), 10%, 100%, 0.15);

    --radius-sm: 10px;
    --radius-md: 16px;
    --radius-lg: 24px;

    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

[data-theme="light"] {
    --bg-primary: #f5f5f7;
    --bg-secondary: #eaeaec;
    --bg-card: #ffffff;
    --bg-card-hover: #ffffff;
    --bg-elevated: #f0f0f2;
    --bg-input: #ffffff;
    --bg-nav: rgba(255, 255, 255, 0.8);
    --bg-nav-mobile: rgba(255, 255, 255, 0.95);
    --nav-hover: rgba(0, 0, 0, 0.05);

    --text-primary: #1a1a2e;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;

    --border: rgba(0, 0, 0, 0.1);
    --border-hover: rgba(0, 0, 0, 0.2);
}

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

::selection {
    background: var(--accent);
    color: #fff;
}

/* ============================================
   NAVIGATION
   ============================================ */
.navbar {
    background: var(--bg-nav);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    transition: all 0.4s var(--ease-out);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.nav-logo {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 8px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    letter-spacing: 0.3px;
    padding: 6px 14px;
    border-radius: 20px;
    transition: all 0.3s var(--ease-out);
    position: relative;
}

.nav-link::after {
    display: none;
}

.nav-link:hover {
    color: var(--text-primary);
    background: var(--nav-hover);
}

.theme-toggle {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 16px;
    color: var(--text-primary);
    transition: all 0.3s var(--ease-out);
}

.theme-toggle:hover {
    border-color: var(--accent);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
    padding: 4px;
}

.bar {
    width: 22px;
    height: 1.5px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all 0.3s var(--ease-out);
}

/* ============================================
   HERO
   ============================================ */
.hero {
    padding: 80px 20px 0;
    text-align: center;
    color: var(--text-primary);
}

.hero-content h1 {
    font-family: var(--font-heading);
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    margin-bottom: 16px;
    text-shadow: none;
}

.hero-content p {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 560px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ============================================
   SECTIONS
   ============================================ */
.calculator-section {
    padding: 48px 2rem 60px;
    max-width: 1200px;
    margin: 0 auto;
    scroll-margin-top: 64px;
}

.calculator-section h2 {
    font-family: var(--font-heading);
    text-align: left;
    font-size: clamp(1.5rem, 4vw, 2rem);
    font-weight: 600;
    letter-spacing: -0.5px;
    margin-bottom: 12px;
    color: var(--text-primary);
    text-shadow: none;
    display: flex;
    align-items: center;
    gap: 16px;
}

.calculator-section h2::before {
    content: '';
    width: 24px;
    height: 1px;
    background: var(--accent);
}

.calculator-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 16px;
    margin-top: 32px;
    margin-bottom: 0;
}

/* ============================================
   CARDS
   ============================================ */
.calculator-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 28px;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.2);
    transition: transform 0.4s var(--ease-out), border-color 0.4s var(--ease-out), box-shadow 0.4s var(--ease-out);
    position: relative;
    overflow: hidden;
    animation: fadeInUp 0.5s var(--ease-out) backwards;
}

.calculator-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent-glow), transparent);
    opacity: 0;
    transition: opacity 0.4s;
}

.calculator-card:hover {
    transform: translateY(-4px);
    border-color: var(--border-hover);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4);
}

.calculator-card:hover::before {
    opacity: 1;
}

.calculator-card:nth-child(2) { animation-delay: 0.05s; }
.calculator-card:nth-child(3) { animation-delay: 0.1s; }
.calculator-card:nth-child(4) { animation-delay: 0.15s; }
.calculator-card:nth-child(5) { animation-delay: 0.2s; }
.calculator-card:nth-child(6) { animation-delay: 0.25s; }
.calculator-card:nth-child(7) { animation-delay: 0.3s; }
.calculator-card:nth-child(8) { animation-delay: 0.35s; }
.calculator-card:nth-child(9) { animation-delay: 0.4s; }

.calculator-card h3 {
    font-family: var(--font-heading);
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--text-primary);
    text-align: left;
    border-bottom: 1px solid var(--border);
    padding-bottom: 14px;
}

/* ============================================
   INPUTS & SELECTS
   ============================================ */
.converter-inputs {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    flex: 1;
    min-width: 120px;
}

.input-group label {
    font-weight: 500;
    color: var(--text-secondary);
    font-size: 0.8rem;
    letter-spacing: 0.3px;
}

.input-group input,
.input-group select,
textarea {
    padding: 10px 14px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    transition: all 0.3s var(--ease-out);
    outline: none;
}

.input-group input:focus,
.input-group select:focus,
textarea:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-subtle);
    background: var(--bg-card-hover);
}

.input-group input::placeholder,
textarea::placeholder {
    color: var(--text-tertiary);
}

.input-group input[readonly] {
    color: var(--accent);
    font-weight: 500;
}

.input-group select {
    cursor: pointer;
    -webkit-appearance: none;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%23999' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

.input-group select option {
    background: var(--bg-elevated);
    color: var(--text-primary);
}

.convert-arrow {
    font-size: 1.2rem;
    color: var(--accent);
    font-weight: 600;
    margin: 0 4px;
    align-self: flex-end;
    margin-bottom: 10px;
    opacity: 0.6;
}

/* ============================================
   PERCENTAGE & INPUT ROWS
   ============================================ */
.percentage-calculator {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.percentage-option h4 {
    margin-bottom: 10px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

.input-row {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}

.input-row input {
    padding: 10px 14px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    width: 100px;
    transition: all 0.3s var(--ease-out);
    outline: none;
}

.input-row input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-subtle);
}

.input-row input::placeholder {
    color: var(--text-tertiary);
}

.input-row input[readonly] {
    color: var(--accent);
    font-weight: 500;
}

.input-row span {
    font-weight: 500;
    color: var(--text-tertiary);
    white-space: nowrap;
    font-size: 0.85rem;
}

/* ============================================
   RESULTS PANELS
   ============================================ */
.tip-results,
.timezone-result {
    background: var(--bg-input);
    border: 1px solid var(--border);
    padding: 16px 20px;
    border-radius: var(--radius-sm);
    margin-top: 12px;
}

.result-item {
    display: flex;
    justify-content: space-between;
    margin-bottom: 10px;
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.result-item:last-child {
    margin-bottom: 0;
    font-size: 1rem;
    color: var(--accent);
    border-top: 1px solid var(--border);
    padding-top: 10px;
}

.timezone-result input {
    width: 100%;
    padding: 10px 14px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--accent);
    font-family: var(--font-body);
    font-size: 0.9rem;
    font-weight: 500;
    margin-top: 8px;
}

/* ============================================
   TIP CALCULATOR
   ============================================ */
.tip-calculator {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* ============================================
   BASIC CALCULATOR
   ============================================ */
.basic-calculator {
    max-width: 300px;
    margin: 0 auto;
}

.calculator-display {
    margin-bottom: 12px;
}

.calculator-display input {
    width: 100%;
    padding: 18px 16px;
    font-size: 1.4rem;
    font-family: var(--font-heading);
    text-align: right;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    letter-spacing: 1px;
}

.calculator-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
}

.calc-btn {
    padding: 16px;
    font-size: 1.05rem;
    font-family: var(--font-heading);
    font-weight: 600;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s var(--ease-out);
    color: var(--text-primary);
}

.calc-btn.number {
    background: var(--bg-input);
}

.calc-btn.number:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
}

.calc-btn.operator {
    background: var(--accent-subtle);
    color: var(--accent);
    border-color: hsla(var(--accent-hue), 91%, 60%, 0.15);
}

.calc-btn.operator:hover {
    background: hsla(var(--accent-hue), 91%, 60%, 0.2);
}

.calc-btn.equals {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
    grid-row: span 2;
}

.calc-btn.equals:hover {
    background: var(--accent-dim);
    box-shadow: 0 4px 16px var(--accent-glow);
}

.calc-btn.clear {
    background: hsla(0, 70%, 55%, 0.1);
    color: var(--danger);
    border-color: hsla(0, 70%, 55%, 0.15);
}

.calc-btn.clear:hover {
    background: hsla(0, 70%, 55%, 0.2);
}

.calc-btn.zero {
    grid-column: span 2;
}

.calc-btn:hover {
    transform: translateY(-1px);
}

.calc-btn:active {
    transform: translateY(1px);
}

/* ============================================
   AGE CALCULATOR
   ============================================ */
.age-calculator {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.age-calculator .calc-btn {
    background: var(--accent);
    color: #fff;
    border: none;
    padding: 12px;
    border-radius: var(--radius-sm);
    font-weight: 600;
}

.age-calculator .calc-btn:hover {
    background: var(--accent-dim);
    box-shadow: 0 4px 16px var(--accent-glow);
}

.age-results {
    background: var(--bg-input);
    border: 1px solid var(--border);
    padding: 16px 20px;
    border-radius: var(--radius-sm);
    margin-top: 8px;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
}

.age-results .result-item {
    border-top: none;
    padding-top: 0;
}

/* ============================================
   TIMEZONE CONVERTER
   ============================================ */
.timezone-converter {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* ============================================
   RESET BUTTON
   ============================================ */
.reset-btn {
    background: var(--bg-input);
    color: var(--text-secondary);
    border: 1px solid var(--border);
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-family: var(--font-body);
    font-size: 0.85rem;
    font-weight: 500;
    transition: all 0.3s var(--ease-out);
    margin-top: 12px;
}

.reset-btn:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    color: var(--text-primary);
    transform: translateY(-1px);
}

.reset-btn:active {
    transform: translateY(1px);
}

/* ============================================
   FOOTER
   ============================================ */
footer {
    border-top: 1px solid var(--border);
    color: var(--text-tertiary);
    text-align: center;
    padding: 40px 2rem;
    margin-top: 40px;
    background: transparent;
}

.footer-content p {
    font-size: 13px;
    opacity: 1;
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 64px;
        flex-direction: column;
        background: var(--bg-nav-mobile);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        width: 100%;
        text-align: center;
        transition: 0.3s var(--ease-out);
        border-bottom: 1px solid var(--border);
        padding: 20px 0;
        gap: 4px;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-link {
        font-size: 16px;
        padding: 12px 20px;
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active .bar:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }

    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }

    .hero-content h1 {
        font-size: 1.75rem;
    }

    .calculator-section {
        padding: 32px 1rem 40px;
    }

    .calculator-section h2 {
        font-size: 1.5rem;
    }

    .calculator-grid {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .converter-inputs {
        flex-direction: column;
        align-items: stretch;
    }

    .convert-arrow {
        align-self: center;
        margin: 4px 0;
        transform: rotate(90deg);
    }

    .input-row {
        flex-direction: column;
        align-items: stretch;
        gap: 8px;
    }

    .input-row input {
        width: 100%;
    }

    .input-row span {
        text-align: center;
        padding: 2px 0;
    }

    .age-results {
        grid-template-columns: 1fr;
    }

    .calculator-buttons {
        gap: 6px;
    }

    .calc-btn {
        padding: 14px;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .calculator-card {
        padding: 20px;
    }

    .hero {
        padding: 80px 1rem 0;
    }

    .calculator-section {
        padding: 24px 12px 32px;
    }

    .nav-container {
        padding: 0 1rem;
    }

    .nav-logo {
        font-size: 1.1rem;
    }
}

/* ============================================
   ANIMATIONS
   ============================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ---------- Reduced Motion ---------- */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
    html { scroll-behavior: auto; }
}

/* ============================================
   FOCUS STYLES
   ============================================ */
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

/* ============================================
   SCROLLBAR
   ============================================ */
::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: hsla(var(--hue), 10%, 100%, 0.15);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: hsla(var(--hue), 10%, 100%, 0.25);
}

/* ============================================
   INLINE STYLE OVERRIDES
   (cards with inline textarea styles)
   ============================================ */
textarea {
    background: var(--bg-input) !important;
    border: 1px solid var(--border) !important;
    color: var(--text-primary) !important;
    border-radius: var(--radius-sm) !important;
    font-family: var(--font-body) !important;
}

textarea:focus {
    border-color: var(--accent) !important;
    box-shadow: 0 0 0 3px var(--accent-subtle) !important;
}

/* ============================================
   SCROLL TO TOP
   ============================================ */
.scroll-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--accent);
    color: #fff;
    border: none;
    font-size: 1.2rem;
    font-weight: bold;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all 0.3s var(--ease-out);
    z-index: 900;
}

.scroll-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.scroll-to-top:hover {
    background: var(--accent-dim);
    transform: translateY(-3px);
}