* {
    box-sizing: border-box;
}

:root {
    color-scheme: dark;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: #0b0b0f;
    color: #fff;
    min-height: 100vh;
    overflow-x: hidden;
}

header {
    text-align: center;
    padding: 56px 20px 24px;
    animation: fade-up 0.7s cubic-bezier(.22, 1, .36, 1) both;
}

.eyebrow {
    margin: 0 0 8px;
    letter-spacing: 7px;
    font-weight: 800;
    animation: soft-glow 3s ease-in-out 0.7s infinite alternate;
}

header h1 {
    margin: 0;
    font-size: clamp(32px, 7vw, 48px);
    letter-spacing: 1px;
}

header > p:last-child {
    margin: 12px auto 0;
    max-width: 620px;
    color: #aaa;
}

main {
    display: flex;
    justify-content: center;
    padding: 28px 18px 80px;
}

.converter {
    width: 100%;
    max-width: 680px;
    background: #15151c;
    border: 1px solid #292933;
    border-radius: 20px;
    padding: clamp(24px, 6vw, 42px);
    box-shadow: 0 18px 60px rgba(0, 0, 0, 0.28);
    animation: card-in 0.8s cubic-bezier(.22, 1, .36, 1) 0.08s both;
    transition: border-color 0.35s ease, box-shadow 0.35s ease, transform 0.35s ease;
}

.converter:focus-within {
    border-color: #3a3a47;
    box-shadow: 0 22px 70px rgba(0, 0, 0, 0.34);
}

.converter h2 {
    margin: 0;
    font-size: 30px;
    text-align: center;
}

.intro {
    margin: 12px auto 26px;
    max-width: 540px;
    text-align: center;
    color: #aaa;
    line-height: 1.5;
}

input[type="file"] {
    position: absolute;
    width: 1px;
    height: 1px;
    opacity: 0;
    pointer-events: none;
}

.choose-button,
#convertButton,
.download-button,
#youtubeButton {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 13px 22px;
    border-radius: 10px;
    font-weight: 800;
    text-decoration: none;
    transition: opacity 0.2s ease, transform 0.2s ease, background-color 0.2s ease, box-shadow 0.2s ease;
}

.choose-button {
    width: 100%;
    background: #fff;
    color: #000;
    cursor: pointer;
}

.choose-button:hover,
#convertButton:hover:not(:disabled),
.download-button:hover,
#youtubeButton:hover:not(:disabled) {
    opacity: 0.88;
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(255, 255, 255, 0.08);
}

.choose-button:active,
#convertButton:active:not(:disabled),
.download-button:active,
#youtubeButton:active:not(:disabled) {
    transform: translateY(0) scale(0.985);
}

.choose-button:focus-visible,
#convertButton:focus-visible,
.download-button:focus-visible,
#youtubeButton:focus-visible,
select:focus-visible,
#youtubeUrl:focus-visible {
    outline: 2px solid #fff;
    outline-offset: 3px;
}

.file-name {
    min-height: 22px;
    margin: 14px 0 26px;
    color: #ddd;
    text-align: center;
    overflow-wrap: anywhere;
    transition: color 0.25s ease, opacity 0.25s ease, transform 0.25s ease;
}

.file-name.file-selected {
    animation: file-selected 0.45s cubic-bezier(.22, 1, .36, 1) both;
}

.settings {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.settings label {
    font-weight: 800;
}

select,
#youtubeUrl {
    width: 100%;
    padding: 14px;
    background: #0b0b0f;
    color: #fff;
    border: 1px solid #33333d;
    border-radius: 9px;
    font-size: 16px;
    transition: border-color 0.2s ease, background-color 0.2s ease, box-shadow 0.2s ease;
}

select:hover,
#youtubeUrl:hover {
    border-color: #454550;
}

select:focus,
#youtubeUrl:focus {
    border-color: #666673;
    background: #0e0e13;
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.04);
    outline: none;
}

#convertButton {
    width: 100%;
    margin-top: 5px;
    border: 0;
    background: #fff;
    color: #000;
    font-size: 16px;
    cursor: pointer;
}

#convertButton:disabled,
#youtubeButton:disabled {
    opacity: 0.45;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

body.is-converting #convertButton {
    animation: button-pulse 1.4s ease-in-out infinite;
}

.progress-wrap {
    margin-top: 24px;
}

.progress-track {
    width: 100%;
    height: 8px;
    overflow: hidden;
    border-radius: 999px;
    background: #292933;
}

.progress-bar {
    position: relative;
    width: 0%;
    height: 100%;
    border-radius: inherit;
    background: #fff;
    transition: width 0.15s ease;
    overflow: hidden;
}

body.is-converting .progress-bar::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.55), transparent);
    transform: translateX(-100%);
    animation: progress-shimmer 1.2s linear infinite;
}

#status,
#youtubeStatus {
    min-height: 24px;
    margin: 12px 0 0;
    color: #aaa;
    text-align: center;
    overflow-wrap: anywhere;
    transition: color 0.25s ease, opacity 0.25s ease;
}

.status-done {
    animation: status-pop 0.45s cubic-bezier(.22, 1, .36, 1) both;
    color: #fff !important;
}

#downloadArea {
    text-align: center;
}

.download-button {
    margin-top: 20px;
    background: #fff;
    color: #000;
    animation: download-in 0.5s cubic-bezier(.22, 1, .36, 1) both;
}

hr {
    margin: 34px 0;
    border: 0;
    border-top: 1px solid #292933;
    opacity: 0.8;
}

.youtube-box {
    animation: fade-up 0.65s cubic-bezier(.22, 1, .36, 1) 0.25s both;
}

.youtube-box h2 {
    font-size: 24px;
}

.youtube-box > p {
    color: #aaa;
    line-height: 1.5;
}

.youtube-box .settings {
    margin-top: 16px;
}

#youtubeButton {
    width: 100%;
    border: 0;
    background: #fff;
    color: #000;
    font-size: 16px;
    cursor: pointer;
}

.note {
    margin: 24px 0 0;
    color: #666;
    font-size: 13px;
    line-height: 1.5;
    text-align: center;
}

footer {
    padding: 30px 20px;
    color: #666;
    text-align: center;
    animation: fade-up 0.6s ease 0.35s both;
}

@keyframes fade-up {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes card-in {
    from {
        opacity: 0;
        transform: translateY(18px) scale(0.985);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@keyframes file-selected {
    0% {
        opacity: 0.35;
        transform: translateY(4px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes download-in {
    from {
        opacity: 0;
        transform: translateY(8px) scale(0.97);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@keyframes status-pop {
    0% {
        opacity: 0.4;
        transform: translateY(3px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes button-pulse {
    0%, 100% {
        opacity: 0.62;
    }
    50% {
        opacity: 0.82;
    }
}

@keyframes progress-shimmer {
    to {
        transform: translateX(100%);
    }
}

@keyframes soft-glow {
    from {
        opacity: 0.78;
    }
    to {
        opacity: 1;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

@media (max-width: 480px) {
    header {
        padding-top: 40px;
    }

    main {
        padding-top: 16px;
    }

    .converter {
        border-radius: 16px;
    }
}