/* ==========================================================================
   ThorDrone DJI-Style Theme — Base Styles
   Reset, layout, typography, header, footer, and form primitives.
   All tokens are --td-* (see DJI-Style-Design-Spec.md).
   ========================================================================== */

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

html {
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth;
}

body {
    background: var(--td-bg-primary);
    color: var(--td-text-primary);
    font-family: var(--td-font-body);
    font-size: var(--td-fs-body);
    font-weight: var(--td-fw-regular);
    line-height: var(--td-lh-relaxed);
    min-height: 100vh;
    overflow-x: hidden;
}

img, picture, video, canvas, svg {
    display: block;
    max-width: 100%;
    height: auto;
}

input, button, textarea, select {
    font: inherit;
    color: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
    overflow-wrap: break-word;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color var(--td-duration-base) var(--td-ease);
}

ul, ol {
    list-style: none;
}

table {
    border-collapse: collapse;
    width: 100%;
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--td-font-display);
    color: var(--td-text-primary);
    line-height: var(--td-lh-snug);
}

h1 {
    font-size: clamp(32px, 5vw, var(--td-fs-h1));
    font-weight: var(--td-fw-bold);
    letter-spacing: var(--td-ls-tight);
    line-height: var(--td-lh-tight);
}

h2 {
    font-size: clamp(24px, 3vw, var(--td-fs-h2));
    font-weight: var(--td-fw-semibold);
    letter-spacing: var(--td-ls-tight);
}

h3 {
    font-size: var(--td-fs-h3);
    font-weight: var(--td-fw-regular);
    letter-spacing: var(--td-ls-normal);
}

h4 {
    font-size: 16px;
    font-weight: var(--td-fw-semibold);
}

p {
    margin-bottom: var(--td-space-3);
}

.text-muted  { color: var(--td-text-secondary); }
.text-tertiary { color: var(--td-text-tertiary); }
.uppercase   { text-transform: uppercase; }
.mono        { font-family: var(--td-font-mono); }

/* --------------------------------------------------------------------------
   Layout System
   -------------------------------------------------------------------------- */
.container,
.td-container {
    max-width: var(--td-container-max);
    margin: 0 auto;
    padding-inline: var(--td-container-padding);
    width: 100%;
}

.section {
    padding: var(--td-space-8) 0;
}

.section--surface {
    background: var(--td-bg-secondary);
}

.section-header {
    margin-bottom: var(--td-space-5);
    text-align: left;
}

.section-header--center {
    text-align: center;
}

.section-title {
    font-family: var(--td-font-display);
    font-size: clamp(24px, 3vw, 32px);
    font-weight: var(--td-fw-semibold);
    letter-spacing: var(--td-ls-tight);
    color: var(--td-text-primary);
}

.section-description {
    color: var(--td-text-secondary);
    font-size: 15px;
    margin-top: var(--td-space-2);
    max-width: 640px;
}

.section-header--center .section-description {
    margin-inline: auto;
}

/* Grid System */
.grid {
    display: grid;
    gap: var(--td-space-3);
}

.grid--2col { grid-template-columns: repeat(2, 1fr); }
.grid--3col { grid-template-columns: repeat(3, 1fr); }
.grid--4col { grid-template-columns: repeat(4, 1fr); }

/* Site structure */
.site {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.site-content {
    flex: 1 0 auto;
}

/* Keep non-front pages clear of the fixed header. */
body:not(.front-page) .site-content {
    padding-top: 64px;
}

/* --------------------------------------------------------------------------
   Header (DJI-style fixed transparent nav)
   -------------------------------------------------------------------------- */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    height: 64px;
    display: flex;
    align-items: center;
    background: var(--td-bg-primary);
    color: var(--td-text-primary);
    border-bottom: 1px solid var(--td-border);
    transition: background var(--td-duration-base) var(--td-ease),
                box-shadow var(--td-duration-base) var(--td-ease),
                color var(--td-duration-base) var(--td-ease),
                border-color var(--td-duration-base) var(--td-ease);
}

/* Front page: transparent over the hero, white text. */
body.front-page .site-header {
    background: transparent;
    color: var(--td-text-inverse);
    border-bottom-color: transparent;
    box-shadow: none;
}

/* Front page scrolled: frosted white. */
body.front-page .site-header.td-nav--scrolled {
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    color: var(--td-text-primary);
    border-bottom-color: var(--td-border);
    box-shadow: var(--td-shadow-nav);
}

.header__inner {
    max-width: var(--td-container-max);
    margin: 0 auto;
    padding-inline: var(--td-space-3);
    height: 64px;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--td-space-3);
}

.header__brand {
    display: flex;
    align-items: center;
    gap: var(--td-space-2);
    flex-shrink: 0;
}

.header__logo {
    display: flex;
    align-items: center;
    line-height: 0;
}

.header__brand-text {
    display: flex;
    flex-direction: column;
    line-height: 1.1;
}

.header__brand-name {
    font-family: var(--td-font-display);
    font-size: 18px;
    font-weight: var(--td-fw-bold);
    letter-spacing: -0.01em;
    color: currentColor;
}

.header__brand-subtitle {
    font-size: 10px;
    color: var(--td-text-secondary);
    letter-spacing: var(--td-ls-wide);
    text-transform: uppercase;
}

body.front-page .site-header:not(.td-nav--scrolled) .header__brand-subtitle {
    color: var(--td-text-inverse-dim);
}

.header__nav {
    flex: 1;
    display: flex;
    justify-content: center;
}

.nav-list {
    display: flex;
    align-items: center;
    gap: var(--td-space-5);
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-list__item {
    position: relative;
}

.nav-list__link {
    font-family: var(--td-font-body);
    font-size: 15px;
    font-weight: var(--td-fw-medium);
    color: var(--td-text-secondary);
    padding: 8px 0;
    display: inline-block;
    position: relative;
    transition: color var(--td-duration-base) var(--td-ease);
}

.nav-list__link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 100%;
    height: 1.5px;
    background: currentColor;
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--td-duration-base) var(--td-ease);
}

.nav-list__link:hover,
.nav-list__item:hover > .nav-list__link,
.nav-list__item--active > .nav-list__link {
    color: var(--td-text-primary);
}

.nav-list__link:hover::after,
.nav-list__item--active > .nav-list__link::after {
    transform: scaleX(1);
}

body.front-page .site-header:not(.td-nav--scrolled) .nav-list__link {
    color: var(--td-text-inverse-muted);
}

body.front-page .site-header:not(.td-nav--scrolled) .nav-list__link:hover,
body.front-page .site-header:not(.td-nav--scrolled) .nav-list__item--active > .nav-list__link {
    color: var(--td-text-inverse);
}

/* Dropdown menu */
.nav-list__item--has-dropdown:hover .nav-dropdown {
    display: grid;
}

.nav-dropdown {
    display: none;
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--td-bg-primary);
    border: 1px solid var(--td-border);
    box-shadow: var(--td-shadow-md);
    padding: var(--td-space-3);
    grid-template-columns: 1fr 1fr;
    gap: var(--td-space-1);
    min-width: 480px;
    z-index: 100;
}

.nav-dropdown__item {
    display: flex;
    align-items: center;
    gap: var(--td-space-2);
    padding: var(--td-space-2) var(--td-space-3);
    color: var(--td-text-secondary);
    border: 1px solid transparent;
    border-radius: var(--td-radius-sm);
    transition: all var(--td-duration-base) var(--td-ease);
}

.nav-dropdown__item:hover {
    background: var(--td-bg-secondary);
    border-color: var(--td-border);
    color: var(--td-text-primary);
}

.nav-dropdown__icon {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
    color: var(--td-text-tertiary);
}

.nav-dropdown__icon svg {
    width: 100%;
    height: 100%;
}

.nav-dropdown__name {
    font-size: 13px;
    font-weight: var(--td-fw-medium);
}

.header__actions {
    display: flex;
    align-items: center;
    gap: var(--td-space-4);
    flex-shrink: 0;
}

.header__toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
}

.toggle-bar {
    display: block;
    width: 24px;
    height: 2px;
    background: currentColor;
    transition: transform var(--td-duration-base) var(--td-ease),
                opacity var(--td-duration-base) var(--td-ease);
}

.header__toggle[aria-expanded="true"] .toggle-bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.header__toggle[aria-expanded="true"] .toggle-bar:nth-child(2) {
    opacity: 0;
}

.header__toggle[aria-expanded="true"] .toggle-bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Mobile Menu */
.mobile-menu {
    display: none;
    position: fixed;
    top: 64px;
    left: 0;
    width: 100%;
    background: var(--td-bg-primary);
    border-bottom: 1px solid var(--td-border);
    padding: var(--td-space-3);
    z-index: 999;
    box-shadow: var(--td-shadow-md);
}

.mobile-menu[hidden] {
    display: none !important;
}

.mobile-menu__nav {
    display: flex;
    flex-direction: column;
    gap: var(--td-space-1);
    margin-bottom: var(--td-space-3);
}

.mobile-menu__link {
    display: block;
    padding: var(--td-space-3);
    color: var(--td-text-primary);
    font-size: 16px;
    font-weight: var(--td-fw-medium);
    border-bottom: 1px solid var(--td-border);
}

.mobile-menu__link:hover {
    color: var(--td-accent);
}

/* --------------------------------------------------------------------------
   Language Switcher
   -------------------------------------------------------------------------- */
.lang-switcher {
    position: relative;
    display: inline-block;
}

.lang-switcher__toggle {
    display: flex;
    align-items: center;
    gap: var(--td-space-1);
    background: transparent;
    border: 1px solid var(--td-border);
    color: inherit;
    font-family: var(--td-font-mono);
    font-size: 12px;
    font-weight: var(--td-fw-medium);
    padding: 6px 12px;
    cursor: pointer;
    transition: border-color var(--td-duration-base) var(--td-ease),
                color var(--td-duration-base) var(--td-ease);
}

body.front-page .site-header:not(.td-nav--scrolled) .lang-switcher__toggle {
    border-color: var(--td-border-dark);
}

.lang-switcher__toggle:hover {
    border-color: var(--td-text-secondary);
}

.lang-switcher__dropdown {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: 4px;
    background: var(--td-bg-primary);
    border: 1px solid var(--td-border);
    box-shadow: var(--td-shadow-md);
    min-width: 120px;
    z-index: 100;
}

.lang-switcher.is-open .lang-switcher__dropdown {
    display: block;
}

.lang-switcher__item {
    display: flex;
    align-items: center;
    gap: var(--td-space-2);
    padding: 8px 12px;
    color: var(--td-text-secondary);
    font-size: 13px;
    border-bottom: 1px solid var(--td-border);
    transition: all var(--td-duration-base) var(--td-ease);
}

.lang-switcher__item:last-child {
    border-bottom: none;
}

.lang-switcher__item:hover {
    background: var(--td-bg-secondary);
    color: var(--td-text-primary);
}

.lang-switcher__item.is-current {
    color: var(--td-text-primary);
}

.lang-switcher__code {
    font-family: var(--td-font-mono);
    font-size: 11px;
    font-weight: var(--td-fw-bold);
    color: var(--td-text-tertiary);
    min-width: 24px;
}

/* --------------------------------------------------------------------------
   Footer (DJI-style dark footer)
   -------------------------------------------------------------------------- */
.td-footer {
    background: var(--td-bg-dark);
    color: var(--td-text-inverse-muted);
    padding: var(--td-space-7) var(--td-container-padding) var(--td-space-4);
    border-top: 1px solid var(--td-border-dark);
}

.td-footer__inner {
    max-width: var(--td-container-max);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--td-space-5);
}

.td-footer__brand {
    font-size: 20px;
    font-weight: var(--td-fw-bold);
    color: var(--td-text-inverse);
    margin-bottom: var(--td-space-2);
}

.td-footer__desc {
    font-size: 14px;
    line-height: var(--td-lh-normal);
    max-width: 300px;
}

.td-footer__col h4 {
    font-size: var(--td-fs-label);
    font-weight: var(--td-fw-medium);
    text-transform: uppercase;
    letter-spacing: var(--td-ls-wide);
    color: var(--td-text-inverse);
    margin-bottom: var(--td-space-3);
}

.td-footer__col ul {
    list-style: none;
}

.td-footer__col li {
    margin-bottom: var(--td-space-2);
}

.td-footer__col a {
    font-size: 14px;
    color: var(--td-text-inverse-muted);
    transition: color var(--td-duration-base) var(--td-ease);
}

.td-footer__col a:hover {
    color: var(--td-text-inverse);
}

.td-footer__bottom {
    max-width: var(--td-container-max);
    margin: var(--td-space-5) auto 0;
    padding-top: var(--td-space-4);
    border-top: 1px solid var(--td-border-dark);
    font-size: 13px;
    color: var(--td-text-inverse-dim);
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--td-space-2);
}

/* --------------------------------------------------------------------------
   Form Primitives (contact form, etc.)
   -------------------------------------------------------------------------- */
.form-group {
    margin-bottom: var(--td-space-3);
}

.form-label {
    display: block;
    font-family: var(--td-font-body);
    font-size: 11px;
    font-weight: var(--td-fw-medium);
    letter-spacing: var(--td-ls-wide);
    text-transform: uppercase;
    color: var(--td-text-secondary);
    margin-bottom: 6px;
}

.form-input,
.form-textarea,
.form-select {
    width: 100%;
    background: var(--td-bg-primary);
    border: 1px solid var(--td-border);
    border-radius: var(--td-radius-sm);
    padding: 10px 14px;
    color: var(--td-text-primary);
    font-family: var(--td-font-body);
    font-size: 14px;
    transition: border-color var(--td-duration-base) var(--td-ease),
                box-shadow var(--td-duration-base) var(--td-ease);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
    outline: none;
    border-color: var(--td-text-primary);
    box-shadow: 0 0 0 1px var(--td-text-primary);
}

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

.form-textarea {
    min-height: 120px;
    resize: vertical;
}

/* --------------------------------------------------------------------------
   Utility Classes
   -------------------------------------------------------------------------- */
.screen-reader-text {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.text-center { text-align: center; }
.text-left   { text-align: left; }
.text-right  { text-align: right; }

.mt-xs { margin-top: var(--td-space-1); }
.mt-sm { margin-top: var(--td-space-2); }
.mt-md { margin-top: var(--td-space-3); }
.mt-lg { margin-top: var(--td-space-4); }
.mt-xl { margin-top: var(--td-space-5); }

.mb-xs { margin-bottom: var(--td-space-1); }
.mb-sm { margin-bottom: var(--td-space-2); }
.mb-md { margin-bottom: var(--td-space-3); }
.mb-lg { margin-bottom: var(--td-space-4); }
.mb-xl { margin-bottom: var(--td-space-5); }

.hidden { display: none !important; }
.visible { display: block !important; }

/* Focus styles */
*:focus-visible {
    outline: 2px solid var(--td-accent);
    outline-offset: 2px;
}

/* Selection */
::selection {
    background: var(--td-text-primary);
    color: var(--td-bg-primary);
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

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

::-webkit-scrollbar-thumb {
    background: #D5D5D5;
    border: 2px solid var(--td-bg-secondary);
}

::-webkit-scrollbar-thumb:hover {
    background: #BDBDBD;
}