/* ===== Variables ===== */
:root {
    --bg: #ffffff;
    --bg-alt: #f5f7fa;
    --text: #1a1a2e;
    --text-muted: #6b7280;
    --accent: #0d6efd;
    --accent-dark: #0b5ed7;
    --accent-glow: rgba(13, 110, 253, 0.25);
    --card-bg: #ffffff;
    --card-border: #e5e7eb;
    --input-bg: #f9fafb;
    --input-border: #d1d5db;
    --header-bg: rgba(255,255,255,0.9);
    --footer-bg: #111827;
    --footer-text: #9ca3af;
    --hero-bg: linear-gradient(135deg, #0f172a 0%, #1e3a5f 50%, #0d6efd 100%);
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.1);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
}

[data-theme="dark"] {
    --bg: #0f172a;
    --bg-alt: #1e293b;
    --text: #f1f5f9;
    --text-muted: #94a3b8;
    --accent: #3b82f6;
    --accent-dark: #2563eb;
    --accent-glow: rgba(59, 130, 246, 0.3);
    --card-bg: #1e293b;
    --card-border: #334155;
    --input-bg: #1e293b;
    --input-border: #475569;
    --header-bg: rgba(15,23,42,0.95);
    --footer-bg: #020617;
    --footer-text: #64748b;
    --hero-bg: linear-gradient(135deg, #020617 0%, #0f172a 50%, #1e3a5f 100%);
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg);
    color: var(--text);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

/* ===== Header ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--header-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--card-border);
}

.header-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 2rem;
}

.logo {
    font-size: 1.4rem;
    font-weight: 900;
    color: var(--text);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.logo span {
    color: var(--accent);
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.header-nav a {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: color 0.2s;
}

.header-nav a:hover {
    color: var(--text);
}

.nav-cta {
    background: var(--accent) !important;
    color: #fff !important;
    padding: 0.5rem 1.2rem;
    border-radius: 8px;
    transition: background 0.2s !important;
}

.nav-cta:hover {
    background: var(--accent-dark) !important;
}

#theme-toggle {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--card-border);
    background: var(--card-bg);
    color: var(--text);
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

#theme-toggle:hover {
    background: var(--bg-alt);
    transform: scale(1.1);
}

/* ===== Hero ===== */
.hero {
    background: var(--hero-bg);
    padding: 10rem 2rem 6rem;
    text-align: center;
    color: #fff;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero-tag {
    display: inline-block;
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(4px);
    border: 1px solid rgba(255,255,255,0.2);
    padding: 0.4rem 1.2rem;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 1.5rem;
}

.hero h1 {
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 900;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    letter-spacing: -1px;
}

.highlight {
    background: linear-gradient(90deg, #60a5fa, #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-desc {
    font-size: 1.15rem;
    color: rgba(255,255,255,0.8);
    max-width: 600px;
    margin: 0 auto 2.5rem;
    line-height: 1.7;
}

.hero-btns {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 3rem;
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 0.9rem 2rem;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 700;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.25s;
    border: none;
}

.btn-primary {
    background: var(--accent);
    color: #fff;
    box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
    background: var(--accent-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 28px var(--accent-glow);
}

.btn-outline {
    background: transparent;
    color: #fff;
    border: 2px solid rgba(255,255,255,0.4);
}

.btn-outline:hover {
    background: rgba(255,255,255,0.1);
    border-color: #fff;
}

/* ===== Hero Stats ===== */
.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.stat {
    text-align: center;
}

.stat strong {
    display: block;
    font-size: 2rem;
    font-weight: 900;
}

.stat span {
    font-size: 0.85rem;
    color: rgba(255,255,255,0.6);
}

/* ===== Sections ===== */
.section {
    padding: 5rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.section-alt {
    background: var(--bg-alt);
    max-width: 100%;
    padding-left: 2rem;
    padding-right: 2rem;
}

.section-alt > * {
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

.section-title {
    text-align: center;
    font-size: 2.2rem;
    font-weight: 900;
    margin-bottom: 0.75rem;
    letter-spacing: -0.5px;
}

.section-sub {
    text-align: center;
    color: var(--text-muted);
    font-size: 1.1rem;
    max-width: 600px;
    margin: 0 auto 3rem;
}

/* ===== Steps ===== */
.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.step-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s, box-shadow 0.2s;
}

.step-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.step-num {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--accent);
    color: #fff;
    font-size: 1.5rem;
    font-weight: 900;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.2rem;
}

.step-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

.step-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* ===== Categories ===== */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 1.2rem;
}

.cat-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 1.5rem 1rem;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s, box-shadow 0.2s;
}

.cat-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.cat-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.cat-card h4 {
    font-size: 0.9rem;
    font-weight: 600;
}

/* ===== Form ===== */
.inv-form {
    max-width: 760px;
    margin: 0 auto;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 20px;
    padding: 2.5rem;
    box-shadow: var(--shadow-md);
}

.form-section-label {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--accent);
    margin-top: 1.5rem;
}

.form-section-label:first-of-type {
    margin-top: 0;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 0;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group.full-width {
    grid-column: 1 / -1;
}

.form-group label {
    display: block;
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 0.35rem;
    color: var(--text);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.7rem 1rem;
    border: 1.5px solid var(--input-border);
    border-radius: 10px;
    background: var(--input-bg);
    color: var(--text);
    font-size: 0.95rem;
    font-family: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
    outline: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.form-group input[type="file"] {
    padding: 0.5rem;
    cursor: pointer;
}

.form-group textarea {
    resize: vertical;
}

.file-hint {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
    display: block;
}

.btn-submit {
    width: 100%;
    padding: 1rem;
    font-size: 1.1rem;
    margin-top: 1rem;
    border-radius: 12px;
}

/* ===== Success ===== */
.form-success {
    text-align: center;
    padding: 3rem 1.5rem;
    max-width: 500px;
    margin: 0 auto;
}

.success-icon {
    width: 72px;
    height: 72px;
    border-radius: 50%;
    background: #10b981;
    color: #fff;
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
}

.form-success h3 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
}

.form-success p {
    color: var(--text-muted);
    font-size: 1rem;
}

/* ===== Footer ===== */
.footer {
    background: var(--footer-bg);
    color: var(--footer-text);
    padding: 3rem 2rem 0;
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}

.footer-brand .logo {
    color: #fff;
    font-size: 1.2rem;
}

.footer-brand .logo span {
    color: var(--accent);
}

.footer-brand p {
    margin-top: 0.75rem;
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-links a {
    color: var(--footer-text);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
}

.footer-links a:hover {
    color: #fff;
}

.footer-contact p {
    font-size: 0.9rem;
    margin-bottom: 0.3rem;
}

.footer-bottom {
    text-align: center;
    padding: 1.5rem 0;
    font-size: 0.8rem;
    color: rgba(255,255,255,0.3);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .header-nav a:not(.nav-cta) {
        display: none;
    }

    .hero {
        padding: 8rem 1.5rem 4rem;
    }

    .hero-stats {
        gap: 1.5rem;
    }

    .stat strong {
        font-size: 1.5rem;
    }

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

    .inv-form {
        padding: 1.5rem;
    }

    .footer-inner {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-links {
        flex-direction: row;
        justify-content: center;
        flex-wrap: wrap;
    }

    .categories-grid {
        grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    }
}